Victor Raul Palomino Alvarez - Academia.edu (original) (raw)

Papers by Victor Raul Palomino Alvarez

RPCAFD: La Revista Peruana de Ciencias de la Actividad Física y del Deporte fue creada el 12 de o... more RPCAFD: La Revista Peruana de Ciencias de la Actividad Física y del Deporte fue creada el 12 de octubre. La razón principal es la difusión de estudios nacionales e internacionales basados en investigaciones originales, revisiones bibliográficas, meta-análisis, cartas al editor, comunicaciones cortas y resúmenes de tesis de Pos Grado. La divulgación de los estudios será gratuita a partir de la fecha. Se pretende durante el transcurso del año 2014 indizar en las mejores bases de datos, mostrando de esta forma la seriedad y el profesionalismo de nuestras ediciones.

Let P ⊂ R 2 be a set of n points. In [1] and [2] an algorithm for counting triangulations and pse... more Let P ⊂ R 2 be a set of n points. In [1] and [2] an algorithm for counting triangulations and pseudo-triangulations of P , respectively, is shown. Both algorithms are based on the divide-and-conquer paradigm, and both work by finding sub-structures on triangulations and pseudo-triangulations that allow the problems to be split. These sub-structures are called triangulation paths for triangulations, or T-paths for short, and zigzag paths for pseudo-triangulations, or PT-paths for short. Those two algorithms have turned out to be very difficult to analyze, to the point that no good analysis of their running time has been presented so far. The interesting thing about those algorithms, besides their simplicity, is that they experimentally indicate that counting can be done significantly faster than enumeration. In this paper we show two new algorithms, one to compute the number of triangulations of P , and one to compute the number of pseudo-triangulations of P. They are also based on T-paths and PT-paths respectively, but use the sweep line paradigm and not divide-and-conquer. The important thing about our algorithms is that they admit a good analysis of their running times. We will show that our algorithms run in time O * (t(P)) and O * (pt(P)) respectively, where t(P) and pt(P) is the largest number of T-paths and PT-paths, respectively, that the algorithms encounter during their execution. Moreover, we show that t(P) = O * (9 n), which is the first non-trivial bound on t(P) to be known. While the algorithm for counting triangulations of [3] is faster in the worst case, O * (3.1414 n), than our algorithm, O * (9 n), there are sets of points where the number of T-paths is O(2 n). In such cases our algorithm may be faster. Furthermore, it is not clear whether the algorithm presented in [3] can be modified to count pseudotriangulations so that its running time remains O * (c n) for some small constant c ∈ R. Therefore, for counting pseudo-triangulations (and possibly other similar structures) our approach seems better.

Molecular Neurodegeneration, 2021

Background There is an association between repetitive head injury (RHI) and a pathologic diagnosi... more Background There is an association between repetitive head injury (RHI) and a pathologic diagnosis of chronic traumatic encephalopathy (CTE) characterized by the aggregation of proteins including tau. The underlying molecular events that cause these abnormal protein accumulations remain unclear. Here, we hypothesized that identifying the human brain proteome from serial CTE stages (CTE I-IV) would provide critical new insights into CTE pathogenesis. Brain samples from frontotemporal lobar degeneration due to microtubule associated protein tau (FTLD-MAPT) mutations were also included as a distinct tauopathy phenotype for comparison. Methods Isobaric tandem mass tagged labeling and mass spectrometry (TMT-MS) followed by integrated differential and co-expression analysis (i.e., weighted gene co-expression network analysis (WGCNA)) was used to define modules of highly correlated proteins associated with clinical and pathological phenotypes in control (n = 23), CTE (n = 43), and FTLD-MAP...

Classroom response systems, such as clickers, have been shown to enhance student engagement, impr... more Classroom response systems, such as clickers, have been shown to enhance student engagement, improve student learning and increase student performance in tertiary education. For teachers, the benefit of these technologies lies in being able to track class progress and identifying misconceptions and gaps in learning. As we head into a more digital world, investigating innovative and digital technologies to improve student engagement and provide immediate feedback to students is important. This paper reports on the processes and outcomes of a pilot project investigating whether the use of an in-class polling tool influenced the attitudes and student levels of engagement in a first year undergraduate core unit. This intervention was implemented in the workshops of a content-heavy human biology unit where first year students come from 23 undergraduate courses with varying educational backgrounds. This project involved sourcing and implementing a suitable polling tool to use in the works...

Journal of Neuroinflammation, 2020

Background Neuroinflammation has been implicated in the pathogenesis of chronic traumatic encepha... more Background Neuroinflammation has been implicated in the pathogenesis of chronic traumatic encephalopathy (CTE), a progressive neurodegenerative disease association with exposure to repetitive head impacts (RHI) received though playing contact sports such as American football. Past work has implicated early and sustained activation of microglia as a potential driver of tau pathology within the frontal cortex in CTE. However, the RHI induced signals required to recruit microglia to areas of damage and pathology are unknown. Methods Postmortem brain tissue was obtained from 261 individuals across multiple brain banks. Comparisons were made using cases with CTE, cases with Alzheimer’s disease (AD), and cases with no neurodegenerative disease and lacked exposure to RHI (controls). Recruitment of Iba1+ cells around the CTE perivascular lesion was compared to non-lesion vessels. TMEM119 staining was used to characterize microglia or macrophage involvement. The potent chemoattractant CCL2 w...

SUMMARYChronic traumatic encephalopathy (CTE) is a progressive tauopathy found in contact sport a... more SUMMARYChronic traumatic encephalopathy (CTE) is a progressive tauopathy found in contact sport athletes, military veterans, and others exposed to repetitive head impacts (RHI)1–6. White matter atrophy and axonal loss have been reported in CTE but have not been characterized on a molecular or cellular level2,7,8. Here, we present RNA sequencing profiles of cell nuclei from postmortem dorsolateral frontal white matter from eight individuals with neuropathologically confirmed CTE and eight age- and sex-matched controls. Analyzing these profiles using unbiased clustering approaches, we identified eighteen transcriptomically distinct cell groups (clusters), reflecting cell types and/or cell states, of which a subset showed differences between CTE and control tissue. Independent in situ methods applied on tissue sections adjacent to that used in the single-nucleus RNA-seq work yielded similar findings. Oligodendrocytes were found to be most severely affected in the CTE white matter sampl...

The Astrophysical Journal, 2020

We report on the detection of a statistically significant flare-like event in the Mg IIλ 2798Å ... more We report on the detection of a statistically significant flare-like event in the Mg IIλ 2798Å emission line and the UVFe II band of CTA102 during the outburst of fall 2017. The ratio between the maximum and minimum of λ3000Å continuum flux for the observation period (2010−2017) is 179±15. Respectively, the max/min ratios 8.1±10.5 and 34.0±45.5 confirmed the variability of the Mg II emission line and of the Fe II band. The highest levels of emission line fluxes recorded coincide with a superluminal jet component traversing through a stationary component located ∼0.1 mas from the 43 GHz core. Additionally, comparing the Mg II line profile in the minimum of activity against the one in the maximum, we found that the latter is broader and blueshifted. As a result of these findings, we can conclude that the non-thermal continuum emission produced by material in the jet moving at relativistic speeds is related to the broad emission line fluctuations. Consequently, these fluctuations are also linked to the presence of broad-line region (BLR) clouds located ∼25 pc from the central engine, outside the inner parsec, where the canonical BLR is located. Our results suggest that during strong activity in CTA102, the source of nonthermal emission and broad-line clouds outside the inner parsec introduces uncertainties in the estimates of black hole (BH) mass. Therefore, it is important to estimate the BH mass, using single-epoch or reverberation mapping techniques, only with spectra where the continuum luminosity is dominated by the accretion disk.

Acta Neuropathologica Communications, 2018

The genetic basis of chronic traumatic encephalopathy (CTE) is poorly understood. Variation in tr... more The genetic basis of chronic traumatic encephalopathy (CTE) is poorly understood. Variation in transmembrane protein 106B (TMEM106B) has been associated with enhanced neuroinflammation during aging and with TDP-43related neurodegenerative disease, and rs3173615, a missense coding SNP in TMEM106B, has been implicated as a functional variant in these processes. Neuroinflammation and TDP-43 pathology are prominent features in CTE. The purpose of this study was to determine whether genetic variation in TMEM106B is associated with CTE risk, pathological features, and ante-mortem dementia. Eighty-six deceased male athletes with a history of participation in American football, informant-reported Caucasian, and a positive postmortem diagnosis of CTE without comorbid neurodegenerative disease were genotyped for rs3173615. The minor allele frequency (MAF = 0.42) in participants with CTE did not differ from previously reported neurologically normal controls (MAF = 0.43). However, in a case-only analysis among CTE cases, the minor allele was associated with reduced phosphorylated tau (ptau) pathology in the dorsolateral frontal cortex (DLFC) (AT8 density, odds ratio [OR] of increasing one quartile = 0.42, 95% confidence interval [CI] 0.22-0.79, p = 0.008), reduced neuroinflammation in the DLFC (CD68 density, OR of increasing one quartile = 0.53, 95% CI 0. 29-0.98, p = 0.043), and increased synaptic protein density (β = 0.306, 95% CI 0.065-0.546, p = 0.014). Among CTE cases, TMEM106B minor allele was also associated with reduced ante-mortem dementia (OR = 0.40, 95% CI 0.16-0.99, p = 0.048), but was not associated with TDP-43 pathology. All case-only models were adjusted for age at death and duration of football play. Taken together, variation in TMEM106B may have a protective effect on CTE-related outcomes.

Journal of neuropathology and experimental neurology, 2018

Traumatic brain injury has been associated with increased risk of Parkinson disease and parkinson... more Traumatic brain injury has been associated with increased risk of Parkinson disease and parkinsonism, and parkinsonism and Lewy body disease (LBD) can occur with chronic traumatic encephalopathy (CTE). To test whether contact sports and CTE are associated with LBD, we compared deceased contact sports athletes (n = 269) to cohorts from the community (n = 164) and the Boston University Alzheimer disease (AD) Center (n = 261). Participants with CTE and LBD were more likely to have β-amyloid deposition, dementia, and parkinsonism than CTE alone (p < 0.05). Traditional and hierarchical clustering showed a similar pattern of LBD distribution in CTE compared to LBD alone that was most frequently neocortical, limbic, or brainstem. In the community-based cohort, years of contact sports play were associated with neocortical LBD (OR = 1.30 per year, p = 0.012), and in a pooled analysis a threshold of >8 years of play best predicted neocortical LBD (ROC analysis, OR = 6.24, 95% CI = 1.5-2...

Brain : a journal of neurology, 2018

The mechanisms underpinning concussion, traumatic brain injury, and chronic traumatic encephalopa... more The mechanisms underpinning concussion, traumatic brain injury, and chronic traumatic encephalopathy, and the relationships between these disorders, are poorly understood. We examined post-mortem brains from teenage athletes in the acute-subacute period after mild closed-head impact injury and found astrocytosis, myelinated axonopathy, microvascular injury, perivascular neuroinflammation, and phosphorylated tau protein pathology. To investigate causal mechanisms, we developed a mouse model of lateral closed-head impact injury that uses momentum transfer to induce traumatic head acceleration. Unanaesthetized mice subjected to unilateral impact exhibited abrupt onset, transient course, and rapid resolution of a concussion-like syndrome characterized by altered arousal, contralateral hemiparesis, truncal ataxia, locomotor and balance impairments, and neurobehavioural deficits. Experimental impact injury was associated with axonopathy, blood-brain barrier disruption, astrocytosis, micro...

JAMA, Jul 25, 2017

Players of American football may be at increased risk of long-term neurological conditions, parti... more Players of American football may be at increased risk of long-term neurological conditions, particularly chronic traumatic encephalopathy (CTE). To determine the neuropathological and clinical features of deceased football players with CTE. Case series of 202 football players whose brains were donated for research. Neuropathological evaluations and retrospective telephone clinical assessments (including head trauma history) with informants were performed blinded. Online questionnaires ascertained athletic and military history. Participation in American football at any level of play. Neuropathological diagnoses of neurodegenerative diseases, including CTE, based on defined diagnostic criteria; CTE neuropathological severity (stages I to IV or dichotomized into mild [stages I and II] and severe [stages III and IV]); informant-reported athletic history and, for players who died in 2014 or later, clinical presentation, including behavior, mood, and cognitive symptoms and dementia. Among...

Experimental & molecular medicine, May 19, 2017

Chronic traumatic encephalopathy (CTE) is a progressive neurodegenerative disorder that is associ... more Chronic traumatic encephalopathy (CTE) is a progressive neurodegenerative disorder that is associated with repetitive head injury and has distinctive neuropathological features that differentiate this disease from other neurodegenerative diseases. Intraneuronal tau aggregates, although they occur in different patterns, are diagnostic neuropathological features of CTE, but the precise mechanism of tauopathy is not known in CTE. We performed whole RNA sequencing analysis of post-mortem brain tissue from patients with CTE and compared the results to normal controls to determine the transcriptome signature changes associated with CTE. The results showed that the genes related to the MAP kinase and calcium-signaling pathways were significantly downregulated in CTE. The altered expression of protein phosphatases (PPs) in these networks further suggested that the tauopathy observed in CTE involves common pathological mechanisms similar to Alzheimer's disease (AD). Using cell lines and ...

Brain injury, 2016

To test the hypothesis that the nucleus basalis of Meynert (nbM), a cholinergic basal forebrain (... more To test the hypothesis that the nucleus basalis of Meynert (nbM), a cholinergic basal forebrain (CBF) cortical projection system, develops neurofibrillary tangles (NFTs) during the progressive pathological stages of chronic traumatic encephalopathy (CTE) in the brain of athletes. To characterize NFT pathology, tau-antibodies marking early, intermediate and late stages of NFT development in CBF tissue obtained at autopsy from eighteen former athletes and veterans with a history of repetitive mild traumatic brain injury (TBI) were used. Analysis revealed that cholinergic nbM neurons develop intracellular tau-immunoreactive changes progressively across the pathological stages of CTE. In particular, there was an increase in pre-tangle (phosphorylated pS422) and oligomeric (TOC1 and TNT1) forms of tau in stage IV compared to stage II CTE cases. The nbM neurons also displayed pathologic TDP-43 inclusions and diffuse extracellular and vascular amyloid-β (Aβ) deposits in CTE. A higher perce...

Proceedings of the twenty-ninth annual symposium on Computational geometry, 2013

We give an algorithm that determines the number tr(S) of straight line triangulations of a set S ... more We give an algorithm that determines the number tr(S) of straight line triangulations of a set S of n points in the plane in worst case time O(n 2 2 n). This is the the first algorithm that is provably faster than enumeration, since tr(S) is known to be Ω(2.43 n) for any set S of n points. Our algorithm requires exponential space. The algorithm generalizes to counting all triangulations of S that are constrained to contain a given set of edges. It can also be used to compute an optimal triangulation of S (unconstrained or constrained) for a reasonably wide class of optimality criteria (that includes e.g. minimum weight triangulations). Finally, the approach can also be used for the random generation of triangulations of S according to the perfect uniform distribution. The algorithm has been implement and is substantially faster than existing methods on a variety of inputs.

Journal of Neural Transmission, 2016

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disorder which may result from repe... more Chronic traumatic encephalopathy (CTE) is a neurodegenerative disorder which may result from repetitive brain injury. A variety of tau-immunoreactive pathologies are present including neurofibrillary tangles (NFT), neuropil threads (NT), dot-like grains (DLG), astrocytic tangles (AT), and occasional neuritic plaques (NP). In tauopathies, cellular inclusions in the cortex are clustered within specific laminae, the clusters being regularly distributed parallel to the pia mater. To determine whether a similar spatial pattern is present in CTE, clustering of the tau-immunoreactive pathology was studied in the cortex, hippocampus, and dentate gyrus in eleven cases of CTE and seven cases of Alzheimer's disease neuropathologic change (ADNC) without CTE. In CTE: (1) all aspects of tau-immunoreactive pathology were clustered and the clusters were frequently regularly distributed parallel to the tissue boundary, (2) clustering was similar in two CTE cases with minimal co-pathology compared with cases with associated ADNC or TDP-43 proteinopathy, (3) in a proportion of cortical gyri, estimated cluster size was similar to that of cell columns of the cortico-cortical pathways, and (4) clusters of the tau-immunoreactive pathology were infrequently spatially correlated with blood vessels. The NFT and NP in ADNC without CTE were less frequently randomly or uniformly distributed and more frequently in defined clusters than in CTE. Hence, the spatial pattern of the tau-immunoreactive pathology observed in CTE is typical of the tauopathies but with some distinct differences compared to ADNC alone. The spread of pathogenic tau along anatomical pathways could be a factor in the pathogenesis of the disease.

Proceedings of the VLDB Endowment, 2015

Hashing is a solved problem. It allows us to get constant time access for lookups. Hashing is als... more Hashing is a solved problem. It allows us to get constant time access for lookups. Hashing is also simple. It is safe to use an arbitrary method as a black box and expect good performance, and optimizations to hashing can only improve it by a negligible delta. Why are all of the previous statements plain wrong? That is what this paper is about. In this paper we thoroughly study hashing for integer keys and carefully analyze the most common hashing methods in a five-dimensional requirements space: (1) data-distribution, (2) load factor, (3) dataset size, (4) read/write-ratio, and (5) un/successful-ratio. Each point in that design space may potentially suggest a different hashing scheme, and additionally also a different hash function. We show that a right or wrong decision in picking the right hashing scheme and hash function combination may lead to significant difference in performance. To substantiate this claim, we carefully analyze two additional dimensions: (6) five representati...

The Electronic Journal of Linear Algebra Ela, Jan 20, 2012

In this paper a method for embedding cocyclic submatrices with "large" determinants of orders 2t ... more In this paper a method for embedding cocyclic submatrices with "large" determinants of orders 2t in certain cocyclic Hadamard matrices of orders 4t is described (t an odd integer). If these determinants attain the largest possible value, we are embedding D-optimal designs. Applications to the pivot values that appear when Gaussian Elimination with complete pivoting is performed on these cocyclic Hadamard matrices are studied.

Neuropathology and applied neurobiology, Jan 21, 2016

To quantify tau pathology of chronic traumatic encephalopathy (CTE) and investigate influence of ... more To quantify tau pathology of chronic traumatic encephalopathy (CTE) and investigate influence of dot-like lesions (DL), brain region, co-morbidity, and sporting career length. Densities of neurofibrillary tangles (NFT), astrocytic tangles (AT), DL, oligodendroglial inclusions (GI), neuropil threads (NT), vacuoles, neurons, and enlarged neurons (EN) were measured in tau-immunoreactive sections of upper cortical laminae of frontal and temporal lobe, hippocampus (HC), amygdala, and substantia nigra (SN) of eleven cases of CTE. DL were a consistent finding in CTE. Densities of NFT, NT and DL were greatest in sectors CA1 and CA2 of the HC. Densities of AT were lower than NFT, small numbers of GI were recorded in temporal lobe, and low densities of vacuoles and EN were consistently present. β-amyloid containing neuritic plaques (NP) also occurred at low density. Densities of NFT, NT, DL, and AT were greater in sulci than gyri while vacuole density was greater in gyri. Principal components...

Alzheimer's research & therapy, Jan 12, 2015

Chronic traumatic encephalopathy (CTE) is a progressive neurodegeneration associated with repetit... more Chronic traumatic encephalopathy (CTE) is a progressive neurodegeneration associated with repetitive head impacts. Understanding Neurologic Injury and Traumatic Encephalopathy (UNITE) is a U01 project recently funded by the National Institute of Neurological Disorders and Stroke and the National Institute of Biomedical Imaging and Bioengineering. The goal of the UNITE project is to examine the neuropathology and clinical presentation of brain donors designated as "at risk" for the development of CTE based on prior athletic or military exposure. Here, we present the rationale and methodology for UNITE. Over the course of 4 years, we will analyze the brains and spinal cords of 300 deceased subjects who had a history of repetitive head impacts sustained during participation in contact sports at the professional or collegiate level or during military service. Clinical data are collected through medical record review and retrospective structured and unstructured family intervie...

Lecture Notes in Computer Science