Distance Estimation Research Papers - Academia.edu (original) (raw)

2025, Infection, Genetics and Evolution

The hematophagous Hemiptera of the subfamily Triatominae are a very diverse group with a variety of morphs, behaviors and distributions. They have great epidemiological importance because many of its members are vectors of the protozoan Trypanosoma cruzi, the agent of Chagas disease. Mepraia is a genus of Triatominae endemic to Chile responsible for transmitting T. cruzi in the sylvatic cycle. Mepraia includes three species, M. gajardoi (18°30 0 -26°30 0 S) M. spinolai (26°30 0 -34°20 0 S) and the recently described M. parapatrica in intermediate zones (24°36 0 -26°51 0 S). Using mitochondrial DNA sequences, we inferred historical processes that led to the current structure of populations. Phylogeographic analyses identified three lineages, congruent with current taxonomy, and populations were highly structured. The times to the most recent common ancestor suggest that M. spinolai is the oldest lineage. We discuss the taxonomic and biogeographic implications of our results.

2025, Perception & Psychophysics

2025

Thirty-seven local and introduced genotypes of hot pepper (Capsicum annuum) were characterized for 20 quantitative and 28 qualitative morphological characters under screen-house conditions. There were highly significant differences among genotypes for most quantitative characters (P<0.001) except primary branch numbers (P>0.05). Exotic genotypes were superior in most traits compared to local genotypes. Local genotypes were characterized by small fruits, late maturity, taller plants with wider canopies compared to introduced genotypes. Local genotypes #31 and #26 were outstanding with respect to numbers of fruits per plant (mean 62) and earliness (60 days), respectively. The first and second principal components (PCs) for quantitative traits accounted for 41.6% and 13.8% of the total variability, respectively. Fruit length, fruit weight and fruit wall thickness largely contributed to PC1. Days to flowering, fruiting, fruit maturity; stem diameter and height; plant height and wi...

2025, Proceedings of the International Astronomical Union

Bipolar planetary nebulae (BPNe) offer a unique opportunity to test models that aim to reproduce the PNe morphologies. In particular, kinematic studies of BPNe allow a reconstruction of the 3D structure of the nebula, otherwise hidden in imaging studies. With this aim in mind we have obtained long-slit echelle spectra of a sample of PNe which cover the full range of observed bipolar morphologies, from elliptical to highly collimated. The analysis of our kinematical data reveals equatorial expansion velocities in the low to medium range (3 to 16 km s -1 ), while the polar expansion velocities range from 18 to 100 km s -1 . We find that the kinematics of the PN K 3-46 can only be explained by a decrease in the expansion velocity with time. The kinematical ages, calculated by using distances estimated from Galactic rotation curves, when available, or by using statistical values, show that the BPNe in our sample -even those which show non-extreme collimation -appear to be young. We have compared our results with the latest theoretical models of BPN formation, and find good agreement between the observed expansion velocities and the numerical models that use magnetic fields coupled with stellar rotation as the collimation mechanism.

2025

Mobile wireless sensors need to know their localizations in many control and monitoring applications. Among all sensors, some know their exact position (i.e., they are equipped with GPS or they are positioned by human intervention). These sensors are called anchors. Some sensors can have different capabilities allowing them to calculate either distances or angles when they receive messages from others nodes. So, they only use anchor positions to obtain an estimated position. However, when sensors are mobile they cannot continuously calculate their position because of the energy constraints. This paper concerns the localization problem in the case where all nodes in the network (anchors and others sensors) are mobile. We propose three techniques following the capabilities of nodes. Thus, each node obtains either an exact position or an approximate position with the knowledge of the maximal error born. Also, we adapt the periods where nodes invoke their localization. Simulation result...

2025, The Astrophysical Journal Supplement Series

We propose a revision of the system developed by Lépine et al. for spectroscopic M-subdwarf classification. Based on an analysis of subdwarf spectra and templates from Savcheva et al., we show that the CaH1 feature originally proposed by Gizis is important in selecting reliable cool subdwarf spectra. This index should be used in combination with the [TiO5, CaH2+CaH3] relation provided by Lépine et al. to avoid misclassification results. In the new system, the dwarf-subdwarf separators are first derived from a sample of more than 80,000 M dwarfs and a "labeled" subdwarf subsample, and these objects are all visually identified from their optical spectra. Based on these two samples, we refit the initial [TiO5, CaH1] relation and propose a new [CaOH, CaH1] relation supplementing the [TiO5, CaH1] relation to reduce the impact of uncertainty in flux calibration on classification accuracy. In addition, we recalibrate the ζ TiO/CaH parameter defined in Lépine et al. to enable its successful application to Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) spectra. Using this new system, we select candidates from LAMOST Data Release 4 and finally identify a set of 2791 new M-subdwarf stars, covering the spectral sequence from type M0 to M7. This sample contains a large number of objects located at low Galactic latitudes, especially in the Galactic anti-center direction, expanding beyond previously published halo-and thick disk-dominated samples. Besides, we detect magnetic activity in 141 objects. We present a catalog for this M-subdwarf sample, including radial velocities, spectral indices and errors, and activity flags, with a compilation of external data (photometric and Gaia Data Release 2 astrometric parameters). The catalog is provided online, and the spectra can be retrieved from the LAMOST Data Release web portal.

2025

We present the first set of definitive trigonometric parallaxes and proper motions from the Cerro Tololo Inter-American Observatory Parallax Investigation (CTIOPI). Full astrometric reductions for the program are discussed, including methods of reference stars selection, differential color refraction corrections, and conversion of relative to absolute parallax. Using data acquired at the 0.9-m at CTIO, full astrometric solutions and V RIJHK s photometry are presented for 36 red and white dwarf stellar systems with proper motions faster than 1. ′′ 0/yr. Of these, thirty three systems have the first ever trigonometric parallaxes, which comprise 41% of MOTION systems (those with proper motions greater than

2025

We use 2MASS photometry to select blue horizontal branch (BHB) candidates covering the sky |b| > 15 • . A 12.5 < J 0 < 15.5 sample of BHB stars traces the thick disk and inner halo to d ⊙ ≃ 9 kpc, with a density 3-5 times that of M giant stars. We base our sample selection strategy on the Century Survey Galactic Halo Project, a survey that provides a complete, spectroscopically-identified sample of blue stars to a similar depth as the 2MASS catalog. We show that a -0.20 < (J -H) 0 < 0.10, -0.10 < (H -K) 0 < 0.10 color-selected sample of stars is 65% complete for BHB stars, and is composed of 47% BHB stars. We apply this photometric selection to the full 2MASS catalog, and see no spatial overdensities of BHB candidates at high Galactic latitude |b| > 50 • . We insert simulated star streams into the data and conclude that the high Galactic latitude BHB candidates are consistent with having no ∼ 5 • wide star stream with density greater than 0.33 objects deg -2 at the 95% confidence level. The absence of structure suggests there have been no major accretion events in the inner halo in the last few Gyr. However, at low Galactic latitudes a two-point angular correlation analysis reveals structure on angular scales θ 1 • . This structure is apparently associated with stars in the thick disk, and has a physical scale of 10-100 pc. Interestingly, such structures are expected by cosmological simulations that predict the majority of the thick disk may arise from accretion and disruption of satellite mergers.

2025, arXiv (Cornell University)

The understanding of the nature of intermediate and high velocity gas in the Milky Way is hampered by a paucity of distance estimates to individual clouds. A project has been started at the David Dunlap Observatory to address this lack of distance measures by observing early-type stars along the line of sight towards these clouds and searching for sodium doublet absorption at the clouds' systemic velocities. Distances to foreground stars (no absorption) and background stars (with absorption) are estimated from spectroscopic parallax, and thus the distance to the bracketed cloud is estimated. In this Letter, we present the first result from this ongoing project, a measurement of the distance to the Draco Cloud, which is the most studied of the intermediate velocity clouds. The result presented here is the first distance bracket which tightly constrains the position of the Draco Cloud. We briefly describe our target selection and observing methodology, and then demonstrate absorption at the velocity of the Draco Cloud for one star (TYC~4194~2188), and a lack of absorption for several other stars. We derive a distance bracket to the Draco Cloud of 463$^{+192}_{-136}$ to 618$^{+243}_{-174}$~pc.

2025, The Astrophysical Journal

The understanding of the nature of intermediate-and high-velocity gas in the Milky Way is hampered by a paucity of distance estimates to individual clouds. A project has been started at the David Dunlap Observatory to address this lack of distance measures by observing early-type stars along the line of sight toward these clouds and searching for sodium doublet absorption at the clouds' systemic velocities. Distances to foreground stars (no absorption) and background stars (with absorption) are estimated from spectroscopic parallax, and thus the distance to the bracketed cloud is estimated. In this Letter, we present the first result from this ongoing project: a measurement of the distance to the Draco Cloud, which is the most studied of the intermediate-velocity clouds. The result presented here is the first distance bracket that tightly constrains the position of the Draco Cloud. We briefly describe our target selection and observing methodology and then demonstrate absorption at the velocity of the Draco Cloud for one star (TYC 4194 2188) and a lack of absorption for several other stars. We derive a distance bracket to the Draco Cloud of 463 to 618 pc.

2025, Journal of Experimental Biology

The present account answers the question of whether desert ants (Cataglyphis fortis) gauge the distance they have travelled by using self-induced lateral optic-flow parameters, as has been described for bees. The ants were trained to run to a distant food source within a channel whose walls were covered with black-and-white gratings. From the food source, they were transferred to test channels of double or half the training width, and the distance they travelled before searching for home and their walking speeds were recorded. Since the animals experience different motion parallax cues when walking in the broader or narrower channels, the optic-flow hypothesis predicted that the ants would walk faster and further in the broader channels, but more slowly and less far in the narrower channels. In contrast to this expectation, neither the walking speeds nor the searching distances depended on the width or height of the channels or on the pattern wavelengths. Even when ventral-field vis...

2025, arXiv (Cornell University)

We introduce a new dual-landmark heuristic for the A* algorithm that references a data structure of size θ(|L| 2 + |V |), where L represents a set of strategically chosen landmark vertices and V the set of vertices in the graph. This heuristic's benefits are permitted by a new approach for computing lower bounds based on generalized polygon inequalities, in which each landmark stores the distances between it and vertices within its graph partition. In this paper, we demonstrate experimental results that show exemplify the space complexity reduction and speedup in comparison to its single-landmark counterpart for large graphs.

2025, ArXiv

We introduce a new heuristic for the A* algorithm that references a data structure much smaller than the one required by the ALT heuristic. This heuristic's benefits are permitted by a new approach for computing lower bounds using generalized polygon inequalities, leveraging distance information from two landmarks as opposed to the common single landmark paradigm. In this paper, we demonstrate that this heuristic stores a reduced amount of preprocessing information in comparison to previous landmark algorithms while performing faster search queries.

2025

and Florida, my path started in Cleveland, OH. I thank my family and friends in Cleveland, who supported and nurtured my ambitions to get into this field. Knowing that I have my sisters, brother, parents, cousins, and everyone else in my huge family there when I need them has been a great comfort throughout the dissertation process. To my little sister Nicole, I'm ready to watch you be the next one to be called "doctor". Just keep pushing yourself. You'll get there. And to my grand-aunt, Phyllis Robinson, I wish you could be around to watch me walk across the stage one more time. Thank you for everything you've done. I'll carry the legacy that started with you into the next phase of my life and onward. When I moved to SUNY Buffalo, in my mind, I was starting my own crusade. I started alone. I had a plan. But life had a different one. I ended up where I am at the time of this writing because of individuals who went out of their way to support me at every step along this journey. As my first research professor, Shambhu Upadhyaya, I thank you. Not only for introducing me to the world of research, but also for providing me with guidance and support both while at Buffalo and afterward. You were the first to ever tell me I should get a PhD. While I was too naïve to listen to you then, I eventually got around to it. I would also like to acknowledge other professors who were there for me after Buffalo, including Florian Buchholz, Brett Tjaden and Xunhua Wang. The time spent with you and lessons learned gave me the confidence and experience that I needed to pursue a PhD. Finally, thanks to my advisor, Michael Laszlo, my committee members and all the other professors and classmates I've interacted with at Nova Southeastern. I've been a dreamer my entire life, imagining so many ways of helping the world but knowing, at some level, that many things were impossible. But with the support and nurture from the all the staff at BBN, I learned that I could build the impossible. This would have never happened without the support and valuable lessons from many of the seniors at BBN, including Jack Marin, Joshua Edmison, Richard Burne, Carl Powell, as well as all of the staff that I've worked with over the years. You are all just as responsible for shaping me into a contributor to science as all my experiences in University. Dr. John Everett (currently at DARPA) deserves a great deal of thanks for initially supporting the idea of being on my committee, nominating me and serving as a true mentor for the 2015 DARPA Rising session, and being the program manager for the first of many research efforts that I hope to have my name on. I now stand on the shoulders of these giants. And to John-Francis Mergen, my mentor and one of my closest friends, I thank you and Lynne for always being there as family and for believing in me. While knowing you, I've seen you make the case for change in the world as only you can make it. In that time, you've taught me that I can do the same, and you can bet that I will. My lifelong friends deserve just as much acknowledgement for their support as everyone else mentioned here. So to Vera Neroni, Elizabeth Brown, Michelle Chu, Cyrus Chu, Douglas Campese, Jessica Lombardo, Scott Goldweber, and everyone else in the surrogate family that has joined me on my crusade, thank you for getting me to this point. Everyone on this page has contributed to the person I am today with a trust that I will strive to create a better tomorrow. I will not fail that trust. And I will not fail to try. Campbell 3 combinatorial optimization problems in graph theory . In all likelihood, this may have been because the size of data used for the problem was typically smaller, making the problem seem trivial while anything larger was deemed intractable. At the time of this writing, progress in practically solving the problem has only occurred in the last six decades. Much of the true scientific investigation started with Alfonso Shimbel, in his introduction of the all-pairs shortest path (APSP) problem . All possible path queries are automatically answered and stored for the APSP problem, while querying is done upon request for the PPSP problem. The solution to the PPSP problem requires an efficient computation of the shortest path between an arbitrary pair of nodes be established. Shortly after Shimbel, Edsger W. Dijkstra was credited with discovering the algorithm that, at the time of this writing, is the best, most well-known, commonly used, and simplest method of solving the shortest path algorithm in a graph . This algorithm is widely known as Dijkstra's algorithm. A decade after its creation, the A* search algorithm showed, by adding a heuristic that estimates distance, that it could run a shortest path query in significantly faster time than Dijkstra's algorithm . Fundamentally, the A* algorithm is Dijkstra's algorithm that takes into account a distance estimation heuristic derived from characteristics of the graph. While other algorithms have been developed in an attempt to contest them, these two greedy optimization algorithms serve as the basis for most modern day shortest path solutions. As researchers find more use for graph theory in the storage, retrieval, and analysis of big data, extremely fast solutions to problems such as the shortest path Campbell 4 problem are in great demand. However, not even Dijkstra's or the A* algorithm can solve the problem for massive datasets without a significant increase in their requirements for computational time and space. For this reason, modern research focuses on performing computations on the graph prior to allowing it to be queried for shortest path. The results of these computations are used to guide, narrow, or inform the search such that arbitrary queries can be performed significantly faster on graphs that represent huge data corpuses. Modern approaches typically exploit mathematical approximation techniques (Delling,

2025, 2005 IEEE International Conference on Ultra-Wideband

The definition of Ultra Wide Band (UWB) signals set by the Federal Communications Commissions (FCC) opened the way to both impulse and non-impulse UWB signal formats. This is reflected within the IEEE 802.15.3a TG, aiming at the definition of a standard for UWB-based high bit rate WPANs. The two main proposals considered in this group are in fact a Multi Band OFDM approach, based on the transmission of nonimpulse OFDM signals combined with Frequency Hopping (FH), and the Direct-Sequence (DS) UWB approach, based on impulse radio transmission of UWB DS-coded pulses. In this paper we analyze the ranging capabilities of the two proposals by first determining the Cramer-Rao Lower Bound (CRLB) for the error in distance estimation using both an ideal channel model and a real channel model taking into account the effect of multipath. Next, we investigate the impact of receiver structure and synchronization sequences adopted in the two proposals on the ranging accuracy. Results show that synchronization sequences play a key role in determining the ranging accuracy. Although the DS-UWB signal is in general best suited for ranging, thanks to its larger bandwidth and its higher frequencies of operation, specific synchronization sequences may in fact lead to better ranging accuracy for the MB-OFDM signal.

2025

The definition of Ultra Wide Band (UWB) signals set by the Federal Communications Commissions (FCC) opened the way to both impulse and non-impulse UWB signal formats. This possibility is reflected within the IEEE 802.15.3a TG, aiming at the definition of a standard for UWB-based high bit rate WPANs. The two main proposals considered in this group are in fact a Multi Band OFDM approach, based on the transmission of non-impulse OFDM signals combined with Frequency Hopping (FH), and the Direct-Sequence (DS) UWB approach, based on impulse radio transmission of UWB DS-coded pulses. In this paper, the ranging capabilities of these two proposals are analyzed by determining the Cramer-Rao Lower Bound (CRLB) for the distance estimation error. The CRLB is evaluated under the condition of both ideal and real, multipath-affected, channel models. Results show that DS-UWB is in general best suited for ranging, thanks to its larger bandwidth and its higher frequencies of operation, and also quantify the degree to which multipath may affect ranging accuracy.

2025, Evaluating the Effectiveness of VR and Traditional Computer Interfaces in Online Architectural Project Presentations

This study investigates the effectiveness of Virtual Reality (VR) versus traditional Keyboard, Screen, Mouse (KSM) interfaces in online architectural presentations. Our hypothesis suggests that viewing the presentation on the monitor that is screen recorded with a VR headset would enhance presence and spatial understanding, leading to more accurate area and distance estimations. A total of 131 architects participated in the study, with 67 in the VR group and 64 in the KSM group. Participants viewed an architectural space either in VR or in KSM and completed tasks to estimate area and distances, followed by a presence questionnaire. Contrary to our hypothesis, the KSM group reported slightly higher presence scores, though not significantly different from the VR group. The VR group showed a minor improvement in distance estimation accuracy, but the practical benefit was minimal. Interestingly, the KSM group significantly outperformed the VR group in area estimation accuracy.

2025, AFTE

A comprehensive series of tests were performed to determine how the gunshot angle of incidence will affect the amount and density of gunshot residue (GSR) upon a target. Test shots were performed at four different angles (0, 30, 45, and 60 degrees). Two handgun calibers (9mm & .45ACP) were included. Testing was at two distances (9"/23cm and 15"/38cm). All targets were photographed. The amount and density of the GSR was quantified using image analysis software and subjected to statistical analysis. The testing demonstrated that as the shooting angle increases from the orthogonal position, the amount and density of GSR on the target is diminished.

2025

We report on VHE γ-observations with the MAGIC telescope of the pulsar PSR B1951+32 and its associated nebula CTB 80. Our data constrain the cutoff energy of the pulsar to be < 32 GeV, assuming the pulsed γ-ray emission to be exponentially cutoff. The upper limit on the flux of pulsed γ-ray emission > 75 GeV is 4.3 · 10 −11 photons cm −2 sec −1 and the upper limit on the flux of steady emission > 140 GeV is 1.5 · 10 −11 photons cm −2 sec −1 . We discuss our results in the framework of recent model predictions and other studies.

2025, Monthly Notices of the Royal Astronomical Society

We present a detailed study of a bipolar, possible Type I planetary nebula (PN), PHR 1315-6555 (PN G305.3-03.1), which was discovered as part of the Macquarie/AAO/Strasbourg Hα planetary nebula project (MASH), and that we considered at the time was an excellent candidate for membership of the distant, compact, intermediate-age open cluster, ESO 96-SC04. The strong evidence for this association is presented here, making this the only known example of a PN physically associated with a Galactic open cluster. Cluster membership is extremely important as it allows for very precise estimates of the fundamental properties of the PN as the cluster is at a known distance. The PN was discovered by one of us (QAP) during systematic MASH searches for new Galactic PNe of the AAO United Kingdom Schmidt Telescope (UKST) Hα survey and had been missed in earlier broad-band surveys, including specific CCD studies of the host cluster. We present original discovery images and Cerro Tololo Inter-American Observatory (CTIO) 4-m MOSAIC-II camera follow-up narrowband images that reveal its bipolar morphology. We also present (i) low-resolution optical spectra that spectroscopically confirm the PN, (ii) accurate radial velocities of PN and cluster stars from high-resolution spectroscopy which show they are consistent and (iii) a reliable, independent distance estimate to the PN using a robust PN distance indicator which agrees with the published cluster distance to within the errors. We also provide preliminary estimates of basic PN properties and abundance estimates from deeper spectra that show it to be of possible Type I chemistry. This is also consistent with its estimated turn-off mass. Taken together, these findings present a powerful case for clear physical association between the PN and host cluster. Results for this association will be of considerable interest to specialists across differing astrophysical disciplines, including PNe, white dwarfs and open clusters.

2025, The Astronomical Journal

Traditionally, the distance to NGC 4038/39 has been derived from the systemic recession velocity, yielding about 20 Mpc for H 0 = 72 km s -1 Mpc -1 . Recently, this widely adopted distance has been challenged based on photometry of the presumed tip of the red giant branch (TRGB), which seems to yield a shorter distance of 13.3 ± 1.0 Mpc and, with it, nearly 1 mag lower luminosities and smaller radii for objects in this prototypical merger. Here we present a new distance estimate based on observations of the Type Ia supernova (SN) 2007sr in the southern tail, made at Las Campanas Observatory as part of the Carnegie Supernova Project. The resulting distance of D SN Ia = 22.3 ± 2.8 Mpc [(m -M) 0 = 31.74 ± 0.27 mag] is in good agreement with a refined distance estimate based on the recession velocity and the large-scale flow model developed by Tonry and collaborators, D flow = 22.5 ± 2.8 Mpc. We point out three serious problems that a short distance of 13.3 Mpc would entail, and trace the claimed short distance to a likely misidentification of the TRGB. Reanalyzing Hubble Space Telescope (HST ) data in the Archive with an improved method, we find a TRGB fainter by 0.9 mag and derive from it a preliminary new TRGB distance of D TRGB = 20.0 ± 1.6 Mpc. Finally, assessing our three distance estimates we recommend using a conservative, rounded value of D = 22 ± 3 Mpc as the best currently available distance to The Antennae.

2025

Based on crowdsourcing data, the study aims at developing a simple method to automatically compute the water transparency. With underwater camera pictures, an image processing technique should provide robust estimations of parameters related to water transparency. We will mainly see the first step: estimating the distance from the image to the camera and the optimal choice of a pattern to photograph.

2025, Journal of Environmental Quality

Experimental apparatus showing solution application, sample extraction, and pressure measurement methods. Only one of the six pairs of sampler and . manometer tubing is shown 30 2a The relative virus concentrations versus pore volumes and fitted breakthrough curves at 0.20 m. (C/C0), is the apparent steady-state value. The markers are labeled by transport experiment number and column letter. The curves were constructed from Eq. [4] 45 2b. The relative virus concentrations versus pore volumes and fitted breakthrough curves at 0.40 m. 46 2c. The relative virus concentrations versus pore volumes and fitted breakthrough curves at 0.80 m. 47 2d. The relative virus concentrations versus pore volumes and fitted breakthrough curves at 1.05 m. 48 3. The relative virus concentration profiles under saturated flow (TE6E) at four sampling times. The average linear velocity was 0.24 m d-1 50 4. The relative virus concentration profile under unsaturated flow (TE3 and TE9) from day 3 (one pore volume at 1.05 m) to day 9, and fitted curve using Eq. [4] and [5], where u = 4.62 d-1 , z is depth (m), y = 0.37 m d-1 , G = 3 m-1 , and L = 0.05 m . . . 51 5. The relative virus concentrations versus pore volumes at the 1.05 m depth and fitted breakthrough curves in transport experiment 10. (C/C0), is the apparent steady-state value. The curves were constructed from Eq. [4]. 55 6. The relative virus concentrations versus pore volumes at the 1.05 m depth and fitted breakthrough curves in transport experiment 12. (C/Co) s is the apparent steady-state value. The curves were constructed from Eq. [4]. 57 7. The relative virus concentration profile with depth from TE10 and TE12 on day 7 (1.8-1.9 pore volumes). The fitted curves were constructed from Eq. [4] and [5], where z is depth (m), y = 0.27 m 61 , G = 3 m-1 , L = 0.05 m, and the organic u, = 0.81 d-1 and the leached u1 = 3.1 di 59 Under unsaturated flow conditions enhanced removal of this virus occurs, and the removed virus are apparently inactivated. Organic matter reduced the removal of virus during transport by unsaturated flow. Virus concentrations reached and maintained a steady-state, exponentially-declining profile with depth. TE3: Long term test with ponding.

2025, arXiv (Cornell University)

Context. Atomic gas in the diffuse interstellar medium (ISM) is organized in filamentary structures. These structures usually host cold and dense molecular clumps. The Galactic magnetic field is considered to play an important role in the formation of these clumps. Aims. Our goal is to explore the role of the magnetic field in the H i-H 2 transition process. Methods. We targeted a diffuse ISM filamentary cloud where gas transitions from atomic to molecular towards the Ursa Major cirrus. We probed the magnetic field properties of the cloud with optical polarization observations. We performed multi-wavelength spectroscopic observations of different species in order to probe the gas phase properties of the cloud. We observed the CO (J=1-0) and (J=2-1) lines in order to probe the molecular content of the cloud. We also obtained observations of the [C ii] 157.6 µm emission line in order to trace the CO-dark H 2 gas and estimate the mean volume density of the cloud. Results. We identified two distinct sub-regions within the cloud. One of the regions is mostly atomic, while the other is dominated by molecular gas although most of it is CO-dark. The estimated plane-of-the-sky magnetic field strength between the two regions remains constant within uncertainties and lies in the range 13-30 µG. The total magnetic field strength does not scale with density. This implies that gas is compressed along the field lines. We also found that turbulence is trans -Alfvénic with M A ≈ 1. In the molecular region, we detected an asymmetric CO clump with its minor axis being closer, with a 24 • deviation, to the mean magnetic field orientation than the angle of its major axis. The H i velocity gradients are in general perpendicular to the mean magnetic field orientation, except for the region close to the CO clump where they tend to become parallel. The latter is likely related to gas undergoing gravitational infall. The magnetic field morphology of the target cloud is parallel to the H i column density structure of the cloud in the atomic region, while it tends to become perpendicular to the H i structure in the molecular region. On the other hand, the magnetic field morphology seems to form a smaller offset angle with the total column density (including both atomic and molecular gas) shape of this transition cloud. Conclusions. In the target cloud where the H i-H 2 transition takes place, turbulence is trans-Alfvénic, hence the magnetic field plays an important role in the cloud dynamics. Atomic gas probably accumulates preferentially along the magnetic field lines and creates overdensities where molecular gas can form. The magnetic field morphology is probed better by the total column density shape of the cloud, and not from its H i column density shape.

2025, preprint

We reported the results of observations of small-scale variability in the hydrogen Balmer lines in Vega. Spectral observations were carried out with low-resolution spectrograph (R ≃ 600) installed in the Main Astronomical Observatory, Ukraine. Spectra were obtained with a time resolution in the second range. It has been found that Vega shows variations in the hydrogen lines H β , Hγ, H δ. This can be interpreted that their variations are non-radial pulsations. The characteristic time of the observed variations ranges from 300 to 1200 sec. The horizontal scale for oscillating elements is about 800 Mm, which is comparable to the solar radius. The radial velocity of the variations is about 36 km/s.

2025, Arxiv preprint astro-ph/0305514

2025, arXiv (Cornell University)

Given any strictly convex norm • on R 2 that is C 1 in R 2 \ {0}, we study the generalized Aviles-Giga functional for Ω ⊂ R 2 and m : Ω → R 2 satisfying ∇ • m = 0. Using, as in the euclidean case • = | • |, the concept of entropies for the limit equation m = 1, ∇ • m = 0, we obtain the following. First, we prove compactness in L p of sequences of bounded energy. Second, we prove rigidity of zero-energy states (limits of sequences of vanishing energy), generalizing and simplifying a result by Bochard and Pegon. Third, we obtain optimal regularity estimates for limits of sequences of bounded energy, in terms of their entropy productions. Fourth, in the case of a limit map in BV , we show that lower bound provided by entropy productions and upper bound provided by one-dimensional transition profiles are of the same order. The first two points are analogous to what is known in the euclidean case • = | • |, and the last two points are sensitive to the anisotropy of the norm • .

2025, arXiv (Cornell University)

2025, Communications in Partial Differential Equations

2025

In large scale network, shortest distance query is a primary operation. In literature there isa number of existingsystems presented that take a landmark embedding approach. These systems select a set of graph nodes as landmarks. Then itcomputes the shortest distances from each landmark to all nodes as an embedding. All the existing methods follow the triangulation based distance estimationthatcalculates approximately the shortest distance among a pair of query nodes as the sum of their distances to a landmark. The landmark set gives a lone global view for all possible queries that could be diameter apart or close by because the landmark selection stage is query independent. Hence it is difficult to accomplishconsistently good performance on all queries as well as the landmark embedding approach may introduce a large relative error. Recently new method presented which is called as a querydependent Local Landmark Scheme (LLS), which identifies a local landmark specific to a pair of qu...

2025, Astronomy & Astrophysics

We present a novel technique for fitting restframe I-band light curves on a data set of 42 type Ia supernovae (SNe Ia). Using the result of the fit, we construct a Hubble diagram with 26 SNe from the subset at 0.01 < z < 0.1. Adding two SNe at z ∼ 0.5 yields results consistent with a flat Λ-dominated "concordance universe" (Ω M , Ω Λ ) = (0.25, 0.75). For one of these, SN 2000fr, new near infrared data are presented. The high redshift supernova NIR data are also used to test for systematic effects in the use of SNe Ia as distance estimators. A flat, Λ = 0, universe where the faintness of supernovae at z ∼ 0.5 is due to grey dust homogeneously distributed in the intergalactic medium is disfavoured based on the high-z Hubble diagram using this small data-set. However, the uncertainties are large and no firm conclusion may be drawn. We explore the possibility of setting limits on intergalactic dust based on B -I and B -V colour measurements, and conclude that about 20 well measured SNe are needed to give statistically significant results. We also show that the high redshift restframe I-band data points are better fit by light curve templates that show a prominent second peak, suggesting that they are not intrinsically underluminous.

2025, THE LIBYAN JOURNAL OF AGRICULTURE

A study was conducted to examine the genetic relationships of eight pea cultivars, including four local
and four introduced cultivars, used in commercial production under an irrigated farming system in Libya..
The cultivars were analyzed using PCR-based techniques to assess genetic diversity. Seven Start Codon
Targeted (SCoT) markers and five Inter-Simple Sequence Repeat (ISSR) markers were employed. These
primers revealed several polymorphic genetic bands with varying molecular weights. The SCoT markers
generated 54 genetic bands, averaging 7.71 bands per primer, while the ISSR markers produced 35
genetic bands, with an average of 7 bands per primer. The genetic diversity for SCoT markers was 0.29,
while ISSR markers showed a diversity of 0.31. The polymorphic information content (PIC) was relatively
low, with an average of 23.0% for SCoT and 24% for ISSR. The dendrogram analysis revealed that the four
local cultivars formed a distinct subgroup, closely related due to their genetic proximity. The high
similarity indices suggest that the local pea plant populations share a strong genetic relationship, which
may be a result of hybridization and the genetic closeness of their parent lines.

2024

Abstract. A classical nova outburst arises from a thermonuclear run-away in the hydrogen-rich material accreted onto the surface of a white dwarf in a binary system. These explosions can produce copious amounts of heavy element enriched material that are ejected violently into the surrounding interstellar medium. In some novae, conditions in the ejecta are suitable for the formation of dust of various compositions, including silicates, amorphous carbon, silicon carbide, and hydrocar-bons. Multiple dust grain types are sometimes produced in the same system. CO formation in novae may not reach saturation, thus in-validating the usual paradigm in which the C:O ratio determines the dust species. A few novae, such as V705 Cas and DZ Cru, have ex-hibited emission features near 6, 8, and 11 µm that are similar to “Unidentified Infrared ” (UIR) features, but with significant differences in position and band structure. Here, we present Spitzer IRS spectra of two recent dusty novae, V2361 Cyg...

2024, Virtual Dashboard Design for Grasping Operations in Teleoperation Systems

A known issue in teleoperation concerns dexterity in grasping objects, which can be severely limited if not properly coupled with perfect stereoscopic vision and force/tactile feedback. This work presents the development and testing of a subsystem used for a virtual dashboard within the Sully teleoperation system, with hardware and software components. It is used to capture images, gather object information, and display a virtual dashboard that provides the operator with information about the distance and reachability of objects, to support stereoscopic vision visualized through a virtual reality headset. The hardware consists of two front cameras, used as eyes for the teleoperated robot, and two Time-of-Flight (ToF) sensors to estimate the distance between the teleoperated robot and the Object of Interest (OoI). The software processes images captured by cameras to identify the objects, detects the OoI, and estimates its distance from the robot using the measurements of ToF sensors. Performance results showed an optimal trade-off between image quality, frame rate, and use experience. Indeed, a mean accuracy of 88% was achieved in identifying and detecting OoIs, and an average mean absolute percentage error (MAPE) of 1.40% to estimate the distance from the robot to the OoI at 120 cm.

2024, Revista Mexicana De Astronomia Y Astrofisica

The study of structural breaks (non-linearity) on the Period-Luminosity relation began more than seven decades ago. Since then, some studies has found breaks in the Period-Luminosity relation. The objective in this work is to look for possible statistical causes of these breaks by means of robust techniques, instead of Ordinary Least Squares, to fit linear regression to OGLE-II and OGLE-IV data. These robust methods allow us to deal with influential points whose presence is a violation to the Ordinary Least Squares assumptions. In fact, fitting the models using M and MM-regressions, we do not find evidence to say that Period-Luminosity relation is non-linear in the LMC. Therefore, light curves of Cepheids suggesting blending, bumps, eclipses and period changes do not have an effect on the Period-Luminosity relation in this galaxy. On the contrary, for SMC, maybe, because of the geometry of the galaxy, there is a possible effect these stars and adequate models could not be found.

2024, EPJ Web of Conferences

Long time surveys yield many light curves among their byproducts, useful to identify candidate Be stars that can be confirmed by spectroscopic follow-ups. We present in this work different techniques we have used to find Be star... more

2024, Proceedings of the International Astronomical Union

A report of a systematic search for Be star candidates in the Small Magellanic Cloud using statistical selection criteria is presented. The results are compared with those obtained with a standard photometric method to search for Be star... more

2024, Monthly Notices of the Royal Astronomical Society

The universality and linearity of the Leavitt law are hypotheses commonly adopted in studies of galaxy distances using Cepheid variables as standard candles. In order to test these hypotheses, we obtain slopes of the Leavitt law using linear regressions of fundamental-mode Cepheids observed by the Optical Gravitational Lensing Experiment project in the Magellanic Clouds. We find that the slopes in V I-bands and in the Wesenheit index behave exponentially, indicating non-linearity. We also find that the slopes obtained using long-period Cepheids can be considered as universal in the V I-bands, but not in the Wesenheit index.

2024, Digital Systems Design

Localization is one of the most challenging and important issues in wireless sensor networks (WSNs), especially if cost-effective approaches are demanded. In this paper, we present intensively discuss and analyze approaches relying on the received signal strength indicator (RSSI). The advantage of employing the RSSI values is that no extra hardware (e.g. ultrasonic or infra-red) is needed for network-centric localization. We studied different factors that affect the measured RSSI values. Finally, we evaluate two methods to estimate the distance; the first approach is based on statistical methods. For the second one, we use an artificial neural network to estimate the distance.

2024, Journal of Communications Software and Systems

Jennic type wireless sensor nodes are utilized together with a novel particle filtering technique for indoor localization. Target objects are localized with an accuracy of around 0.25 meters. The proposed technique introduces a new particle generation and distribution technique to improve current estimation of object positions. Particles are randomly distributed around the object in the sensing area within a circular strip of 2 STD of object distance measurements. Particle locations are related to object locations by using Gaussian weight distribution methods. Object distances from the transmitters are determined by using received RSSI values and ITU-R indoor propagation model. Measured object distances are used together with the particle distances from the transmitters to predict the object locations.

2024, The Astronomical Journal

We present the results from a spectroscopic study of 1080 nearby active M dwarfs, selected by correlating the 2MASS and ROSAT catalogs. We have derived the spectral types and estimated distances for all of our stars. The spectral types range between K5 and M6. Nearly half of our stars lie within 50 pc. We have measured the equivalent width of the Hα emission line. Our targets show an increase in chromospheric activity from early to mid-spectral types, with a peak in activity around M5. Using the count rate and hardness ratios obtained from the ROSAT catalog, we have derived the X-ray luminosities. Our stars display a "saturation-type" relation between the chromospheric and coronal activity. The relation is such that log L X / L bol remains "saturated" at a value of ∼-3 for varying Hα equivalent width. We have found 568 matches in the USNO-B catalog, and have derived the tangential velocities for these stars. There is a slight trend of decreasing chromospheric activity with age, such that the stars with higher v tan have lower Hα equivalent widths. The coronal emission, however, remains saturated at a value of log L X / L bol ∼-3 for varying tangential velocities, suggesting that the coronal activity remains saturated with age. We do not find any break in the saturation-type relation at the spectral type where stars become fully convective (∼M3.5). Most of the stars in our sample show more coronal emission than the dMe stars in the Hyades and Praesepe clusters, and have v tan < 40km/s, suggesting a young population.

2024, The Astronomical Journal

Photometric (V J R C I C ) and spectroscopic (6000-9500 Å) observations of high proper motion stars discovered during the first phase of the SuperCOSMOS RECONS (SCR) search are used to estimate accurate distances to eight new nearby red dwarfs, including probable 10 pc sample members SCR 1845-6357 (M8.5V at 4.6 pc), the binary SCR 0630-7643AB (M6.0VJ at 7.0 pc), and SCR 1138-7721 (M5.0V at 9.4 pc). Distance estimates are determined using a suite of new photometric color-M Ks relations defined using a robust set of nearby stars with accurate V RIJHK s photometry and trigonometric parallaxes. These relations are utilized, with optical and infrared photometry, to estimate distances on a uniform system (generally good to 15%) for two additional samples of red nearby star candidates: several recently discovered members of the solar neighborhood, and known faint stars with proper motions in excess of 1.0 ′′ /yr south of DEC = -57.5. Of those without accurate trigonometric parallax measurements, there are five stars in the first sample and three in the second that are likely to be within 10 pc. The two nearest are SO 0253+1652 (M7.0V at 3.7 pc) and DEN 1048-3956 (M8.5V at 4.5 pc). When combined with SCR 1845-6357, these three stars together represent the largest increase in the 5 pc sample in several decades. Red spectra are presented for the red dwarfs and types are given on the RECONS standard spectral system. Red spectra are also given for two new nearby white dwarfs for which we estimate distances from the photometry of less than 20 pc -WD 0141-675 (LHS 145, 9.3 pc) and SCR 2012-5956 (17.4 pc). WD 0141-675 brings the total number of systems nearer than 10 pc discussed in this paper to 12.

2024, Geoinformatica

The geographic application domain includes important information such as design plans, record drawings, photographs, and video data records. The corresponding geographic information systems (GISs) should maintain a specific model for each geographic data modality such as geographic video model for video records. Real-time 3-D geographic information systems provide comprehensive interface to complex and dynamic databases and truly immersive capability for

2024, Astronomy & astrophysics. Supplement series

This paper presents theoretical integrated colours of old stellar populations as computed adopting an homogeneous set of stellar models, covering all the major evolutionary phases of globular cluster stars. We show that adopting Reimers parameterization of mass loss rates, the choice η = 0.4 gives synthetic CM diagrams of simple stellar populations in agreement with the typical dependence of globular cluster CM diagrams on metallicity. We present theoretical U -B, B -V , V -R and V -I integrated colours for cluster metallicity in the range Z = 0.0001 to 0.02 and for age between 8 and 15 Gyr. The stochastic occurrence of luminous post-AGB stars is briefly discussed. We find that for an age t ∼ 15 Gyr the predicted integrated colours appear in good agreement with available data for both galactic and LMC old globulars. We discuss the uncertainties of integrated colours due to statistical fluctuations in the number of luminous stars, giving for each colour the expected uncertainty as a function of the cluster integrated V -magnitude. Comparison with discloses that the still existing differences in the evolutionary results appear of minor relevance as far as integrated cluster colours is concerned. Finally, we show that reasonable uncertainties either in the cluster age or in the efficiency of mass loss have marginal effects on the predicted colours.

2024, IEEE INFOCOM 2008 - The 27th Conference on Computer Communications

In road networks, sensor nodes are deployed sparsely (hundreds of meters apart) to save costs. This makes the existing localization solutions based on the ranging ineffective. To address this issue, this paper introduces an autonomous passive localization scheme, called APL. Our work is inspired by the fact that vehicles move along routes with a known map. Using vehicle-detection timestamps, we can obtain distance estimates between any pair of sensors on roadways to construct a virtual graph composed of sensor identifications (i.e., vertices) and distance estimates (i.e., edges). The virtual graph is then matched with the topology of road map, in order to identify where sensors are located in roadways. We evaluate our design in local roadway and show that our distance estimate method works well. In addition, we show that our localization scheme is effective in a road network with eighteen intersections, where we found no location matching error, even with a maximum sensor time synchronization error of 0.3[sec] and the vehicle speed deviation of 10[km/h].

2024, Annals of Biology

Lepidium sativum L. is a fast-growing, edible and medicinal plant that belongs to the family Brassicaceae. Indian system of medicinal and health (ISHM) recognizes this plant as a source of several medicinal and nutraceutical factors. Ninety-four accessions collected from 19 states of India were assessed for genetic diversity using inter-simple sequence repeat (ISSR) marker. Ten ISSR primers amplified a total of 172 bands across the 94 accessions and out of these, 139 bands were found to be polymorphic and 33 as monomorphic. The percentage polymorphism varied from 60.00 to 91.30% with an average of 80.10%. The polymorphism information content (PIC) varied from 0.14 to 0.39 with an average of 0.27. The Jaccard similarity coefficient ranged from 0.11 to 0.89 with minimum between accession LS61 and LS60 and maximum between accession LS95 and LS81. Cluster analysis based on UPGMA grouped all the 94 accessions into three major clusters with accessions per cluster ranging from 12 to 45. Similar to UPGMA clustering, PCA also differentiated all the accessions into three major groups. Modelbased clustering determined three sub-populations (K = 3). Further, analysis of molecular variance showed that 67% of allelic diversity was attributed to individual accessions within populations while 33% was distributed among populations. This preliminary study shows that significant variability exists in the collected accessions.

2024, IEEE Transactions on Information Technology in Biomedicine

We present an original information theoretic measure of heart motion based on the Shannon's differential entropy (SDE), which allows heart wall motion abnormality detection. Based on functional images, which are subject to noise and segmentation inaccuracies, heart wall motion analysis is acknowledged as a difficult problem, and as such, incorporation of prior knowledge is crucial for improving accuracy. Given incomplete, noisy data and a dynamic model, the Kalman filter, a well-known recursive Bayesian filter, is devised in this study to the estimation of the left ventricular (LV) cavity points. However, due to similarity between the statistical information of normal and abnormal heart motions, detecting and classifying abnormality is a challenging problem, which we investigate with a global measure based on the SDE. We further derive two other possible information theoretic abnormality detection criteria, one is based on Rényi entropy and the other on Fisher information. The proposed methods analyze wall motion quantitatively by constructing distributions of the normalized radial distance estimates of the LV cavity. Using 269 × 20 segmented LV cavities of short-axis MRI obtained from 30 subjects, the experimental analysis demonstrates that the proposed SDE criterion can lead to a significant improvement over other features that are prevalent in the literature related to the LV cavity, namely, mean radial displacement and mean radial velocity.

2024, Revista mexicana de astronomía y astrofísica

In this work we explore the possibility that the observed time variable emission at radio frequencies from the CEN 1a system has a thermal origin. The observed flux densities and spectral indices from this source clearly deviate from the standard stellar wind model around a massive star, and seem to be consistent with optically-thin thermal emission. Here we investigate the radio-continuum free-free emission from a stellar wind with time-dependent injection parameters, which result in the formation of internal shocks that travel away from the central star. Although our model is able to predict the observed flux densities and spectral indices from the CEN 1a source, it fails to explain the detected variability in the optically-thin regime. We conclude that the observed emission has a composite nature, with thermal and non-thermal contribution.

2024, Proceedings of the 9th annual international conference on Mobile computing and networking

Wireless Sensor Networks have been proposed for a multitude of location-dependent applications. For such systems, the cost and limitations of the hardware on sensing nodes prevent the use of range-based localization schemes that depend on absolute pointto-point distance estimates. Because coarse accuracy is sufficient for most sensor network applications, solutions in range-free localization are being pursued as a cost-effective alternative to more expensive range-based approaches. In this paper, we present APIT, a novel localization algorithm that is range-free. We show that our APIT scheme performs best when an irregular radio pattern and random node placement are considered, and low communication overhead is desired. We compare our work via extensive simulation, with three state-of-the-art range-free localization schemes to identify the preferable system configurations of each. In addition, we study the effect of location error on routing and tracking performance. We show that routing performance and tracking accuracy are not significantly affected by localization error when the error is less than 0.4 times the communication radio radius.