Kim Gain | Hjhjhu - Academia.edu (original) (raw)

Papers by Kim Gain

Selected Areas in …, 2007

Static spectrum allocation prohibits radio devices from using spectral bands designated for other... more Static spectrum allocation prohibits radio devices from using spectral bands designated for others. As a result, some bands are under-utilized while other bands are over-populated with radio devices. To remedy this problem, the concept of spectrum agility has been considered so as to enable devices to opportunistically utilize others' spectral bands. In order to help realize this concept, we establish an analytical model to derive performance metrics, including spectrum utilization and spectrum-access blocking time in spectral-agile communication systems. We then propose three basic building blocks for spectralagile systems, namely spectrum opportunity discovery, spectrum opportunity management, and spectrum usage coordination, and develop protocols for each blocks. These protocols are integrated with the IEEE 802.11 protocol, and simulated using ns-2 to evaluate the protocol overhead. The simulation results show that our proposed protocols can improve the throughput of an IEEE 802.11 wireless LAN by 90% for the simulated scenarios, and the improvements matched well our analytical model. These results demonstrate the great potential of using spectrum agility for improving spectral utilization in an efficient, distributed, and autonomous manner.

Journal of Environmental Engineering-asce, 2002

FEBS letters, 2006

C(2)H(2)-zinc finger proteins that contain the EAR repressor domain are thought to play a key rol... more C(2)H(2)-zinc finger proteins that contain the EAR repressor domain are thought to play a key role in modulating the defense response of plants to abiotic stress. Constitutive expression of the C(2)H(2)-EAR zinc finger protein Zat10 in Arabidopsis was found to elevate the expression of reactive oxygen-defense transcripts and to enhance the tolerance of plants to salinity, heat and osmotic stress. Surprisingly, knockout and RNAi mutants of Zat10 were also more tolerant to osmotic and salinity stress. Our results suggest that Zat10 plays a key role as both a positive and a negative regulator of plant defenses.

Photonics Technology …, 1998

We use for what we believe is the first time narrowband end-reflectors to reduce losses through s... more We use for what we believe is the first time narrowband end-reflectors to reduce losses through short-wavelength amplified stimulated emission (ASE) in silica-based erbium-doped fiber amplifiers operating at wavelengths above 1570 nm. The end-reflectors feed a small fraction of the ASE, up to a few tenths of a milliwatt, back into the amplifying fiber. The reflected ASE compresses the short-wavelength gain and thus reduces the ASElosses, from, e.g., 50 mW for a launched pump power of 110 mW at 980 nm without end-reflector to 10 mW with an optimized endreflector. We investigate possible improvements of gain (around 5 dB) and output power (up to 17 mW), and the influence of the amount and wavelength of the feedback.

Physical Review E, 2000

In a high-gain free-electron laser ͑FEL͒ employing a planar undulator, strong bunching at the fun... more In a high-gain free-electron laser ͑FEL͒ employing a planar undulator, strong bunching at the fundamental wavelength can drive substantial bunching and power levels at the harmonic frequencies. In this paper we investigate the three-dimensional evolution of harmonic radiation based on the coupled Maxwell-Klimontovich equations that take into account nonlinear harmonic interactions. Each harmonic field is a sum of a linear amplification term and a term driven by nonlinear harmonic interactions. After a certain stage of exponential growth, the dominant nonlinear term is determined by interactions of the lower nonlinear harmonics and the fundamental radiation. As a result, the gain length, transverse profile, and temporal structure of the first few harmonics are eventually governed by those of the fundamental. Transversely coherent third-harmonic radiation power is found to approach 1% of the fundamental power level for current high-gain FEL projects.

Journal of The American Geriatrics Society, 2007

OBJECTIVES: To explore the potential of using step activity monitoring to detect differences in a... more OBJECTIVES: To explore the potential of using step activity monitoring to detect differences in ambulatory activity associated with advancing age and declining function in community-dwelling seniors.DESIGN: Cross-sectional pilot study.SETTING: General communities of Seattle, Washington; Catonsville, Maryland; and Durham, North Carolina.PARTICIPANTS: Thirty healthy younger adults, 28 healthy older adults, and 12 older adults reporting functional limitations.MEASUREMENTS: Ambulatory activity data were collected over 6 days with the StepWatch 3. Average daily values were calculated for number of steps, number of minutes of activity, number of activity bouts, variability of minute-to-minute activity, and randomness of minute-to-minute activity fluctuations.RESULTS: Healthy older adults engaged in fewer bouts of activity (P=.03) and displayed less-variable activity (P=.02) than younger adults. Older adults reporting functional limitations not only engaged in fewer bouts of activity (P=.009) and less variable activity (P<.001) than younger adults, but also accumulated fewer total steps (P=.003) and minutes of activity (P=.008) and had less-random minute-to-minute activity fluctuations (P=.02).CONCLUSION: Step activity monitoring data were useful for detecting differences in ambulatory activity according to age and functional limitation. Monitor-based measures reflecting patterns of ambulatory activity show promise for use in studies of physical functioning.

Journal of Neuro-oncology, 2004

We analyzed 19 cases of cytologically confirmed leptomeningeal carcinomatosis (LMC) treated at ou... more We analyzed 19 cases of cytologically confirmed leptomeningeal carcinomatosis (LMC) treated at our institution over the past 11 years. LMC was the initial manifestation of gastric cancer in 2 patients. With the exception of 1 patient, the primary gastric cancer was Borrmann type III or IV, and 88% had poorly differentiated or signet-ring cell histology. The gastric cancer was progressive or a recurrent disease in most of the patients. The distribution of extraneural metastasis suggested that Batson's venous plexus might be the predominant route to the subarachnoid space. Eighty percent of the patients had multiple neuraxis syndrome, and the combination of brain plus cranial nerve syndrome was the most common manifestation. Computed tomography (CT) findings were abnormal in a minor proportion of the patients, while magnetic resonance imaging (MRI) revealed abnormality in 67% of the patients, which could help the diagnosis. LMC complicating gastric cancer was ultimately fatal. Median survival was very short, 4 weeks. By univariate analysis, good performance status, intrathecal chemotherapy, and low CSF LDH concentration favored survival. Multivariate analysis revealed that the administration of CSF chemotherapy was the independent prognostic factor for survival.

Physical review …, 1996

EA LAZARUS, GA NAVRATIL, CM GREENFIELD, EJ STRAIT, ME AUSTIN, KH BURRELL, TA CASPER, DR BAKER, JC... more EA LAZARUS, GA NAVRATIL, CM GREENFIELD, EJ STRAIT, ME AUSTIN, KH BURRELL, TA CASPER, DR BAKER, JC DEBOO, EJ DOYLE, R DURST, JR FERRON, CB FOEST, P GOHIL, RJ GROEBNER, WW HEIDBRINK, RM HONG, WA HOULBERG, AW HOWALD, CL HSIEH, AW ...

In this presentation, we report excellent electrical and optical characteristics of a dual gate p... more In this presentation, we report excellent electrical and optical characteristics of a dual gate photo thin film transistor (TFT) with bi-layer oxide channel, which was designed to provide virgin threshold voltage (VT) control, improve the negative bias illumination temperature stress (NBITS) reliability, and offer high photoconductive gain. In order to address the photo-sensitivity of phototransistor for the incoming light, top transparent InZnO (IZO) gate was employed, which enables the independent gate control of dual gate photo-TFT without having any degradation of its photosensitivity. Considering optimum initial VT and NBITS reliability for the device operation, the top gate bias was judiciously chosen. In addition, the speed and noise performance of the photo-TFT is competitive with silicon photo-transistors, and more importantly, its superiority lies in optical transparency.

Optics …, 2003

An experimental system has been assembled to measure the absolute values of the Raman gain spectr... more An experimental system has been assembled to measure the absolute values of the Raman gain spectrum for millimeter-thick glass samples. Results are reported for two new oxide glasses with Raman gain coefficients as much as 30 times larger than that of fused silica and more than twice its spectral coverage.

Journal of Bone and …, 2001

Spine fractures usually occur less commonly in men than in women. To identify the structural basi... more Spine fractures usually occur less commonly in men than in women. To identify the structural basis for this gender difference in vertebral fragility, we studied 1013 healthy subjects (327 men and 686 women) and 76 patients with spine fractures (26 men and 50 women). Bone mineral content (BMC), cross-sectional area (CSA), and volumetric bone mineral density (vBMD) of the third lumbar vertebral body (L3) were measured by posteroanterior (PA) and lateral scanning using dual-energy X-ray absorptiometry (DXA). In this cross-sectional study, the diminution in peak vertebral body BMC from young adulthood to old age was less in men than in women (6% vs. 27%). This diminution was the net result of two opposing changes occurring concurrently throughout adult life: the removal of bone adjacent to marrow on the inner (endosteal) surface by bone resorption and the deposition of bone on the outer (periosteal) surface by bone formation. For L3, we estimated that men resorbed 3.7 g and deposited 3.1 g, producing a net loss of 0.6 g from young adulthood to old age and women resorbed 3.1 g and deposited only 1.2 g, producing a net loss of 1.9 g. Thus, based on our indirect estimates of periosteal gain and endosteal loss across life, the observed net diminution in BMC during aging was less in men than women because absolute periosteal bone formation was greater in men than women (3.1 g vs. 1.2 g) not because absolute bone resorption was less in men. On the contrary, the absolute amount of bone resorbed was greater in men than women (3.7 g vs. 3.1 g). Periosteal bone formation also increased vertebral body CSA 3-fold more in men than in women, distributing loads onto a larger CSA, so that the load imposed per unit CSA decreased twice as much in men than in women (13% vs. 5%). In men and women with spine fractures, CSA and vBMD were reduced relative to age-matched controls. However, vBMD was no different to the adjusted vBMD in age-matched controls derived assuming controls had no periosteal bone formation during aging. Thus, large amounts of bone are resorbed in men as well as in women, accounting for the age-related increase in spine fractures in both genders. Periosteal bone formation increases CSA and offsets bone loss in both genders but more greatly in men, accounting for the lower incidence of spine fractures in men than in women. We speculate that reduced periosteal bone formation, during growth or aging, may be in part responsible for both reduced vertebral size and reduced vBMD in men and women with spine fractures. Sexual dimorphism in vertebral fragility is more the result of gender differences in age-related bone gain than age-related bone loss.

Annals of Hematology

The current study investigated molecular cytogenetic characteristics of chronic myeloid leukemia ... more The current study investigated molecular cytogenetic characteristics of chronic myeloid leukemia (CML) using genome-wide, single nucleotide polymorphism arrays (SNP-A) capable of detecting cryptic submicroscopic genomic aberrations. Genome-Wide Human SNP 6.0 Array (Affymetrix, CA, USA) was performed in 118 patients having CML, chronic phase. Thirty-nine clonal aberrations (CAs) were identified (35 losses, two gains, two copy neutral loss of heterozygosity) that were not detected by metaphase cytogenetics in 25 patients (21%). The 9q34 deletions were found in 10% of cases, while 22q11.2 deletions were observed in 12% of cases. Seven patients (6%) harbored both 5′-ABL and 3′-BCR deletions adjacent to the t(9;22) breakpoint. Copy number gains were identified at 8p and 9p, and losses at 2q, 7q, 8q, 9q, 11q, 13q, 16p, and 22q. When we compared the treatment outcome of imatinib therapy between patients with and without CAs identified by SNP-A, treatment failure and progression to advanced disease were not significantly different (p > 0.05). In addition, according to the presence of deletions of 9q34 and/or 22q11.2 identified by SNP-A, the treatment outcome did not show any significant differences (p > 0.05). Our data suggests that SNP-A analysis is a useful tool for detection of clonal aberrations including deletions adjacent to the t(9;22) breakpoint in the CML cancer genome. However, clonal aberrations detected by SNP-A could not improve a prognostic stratification in CML patients with chronic phase.

Journal of Instrumentation, 2010

An analog hadron calorimeter (AHCAL) prototype of 5.3 nuclear interaction lengths thickness has b... more An analog hadron calorimeter (AHCAL) prototype of 5.3 nuclear interaction lengths thickness has been constructed by members of the CALICE Collaboration. The AHCAL prototype consists of a 38-layer sandwich structure of steel plates and highly-segmented scintillator tiles that are read out by wavelength-shifting fibers coupled to SiPMs. The signal is amplified and shaped with a custom-designed ASIC. A calibration/monitoring system based on LED light was developed to monitor the SiPM gain and to measure the full SiPM response curve in order to correct for non-linearity. Ultimately, the physics goals are the study of hadron shower shapes and testing the concept of particle flow. The technical goal consists of measuring the performance and reliability of 7608 SiPMs. The AHCAL was commissioned in test beams at DESY and CERN. The entire prototype was completed in 2007 and recorded hadron showers, electron showers and muons at different energies and incident angles in test beams at CERN and Fermilab.

Proceedings of the …, 2006

Low power CMOS RF digitally programmable gain amplifiers for dual-band (Band-III and L-Band) DAB/... more Low power CMOS RF digitally programmable gain amplifiers for dual-band (Band-III and L-Band) DAB/T-DMB receiver IC are implemented using 0.18 µ µ µ µm CMOS process. For a stable operation among large interference situation, it is required to have wide gain range and fine resolution in RF domain. In order to meet such requirements, various programmable gain amplifier architectures are proposed. Also employing a Differential Multiple Gated TRansistor (DMGTR) technique which is a differential circuit gm″ ″ ″ ″ cancellation method, maximum 22 dB IIP3 improvement is obtained. The IC exhibits 60 dB gain range with 0.25 dB resolution, 2.7 dB NF, -14 dBm IIP3 and 42 dB voltage gain at 22 mW power consumption for L-Band case, 50 dB gain range with 0.25 dB resolution, 3 dB NF, -5 dBm IIP3 and 28 dB voltage gain for Band-III case at 16mW power consumption.

Gut, 1979

Zymogram studies of peptide hydrolases from the human intestinal brush border and cytoplasmic fra... more Zymogram studies of peptide hydrolases from the human intestinal brush border and cytoplasmic fractions produced multiple bands--that is, up to seven--while the brush border membrane produced only a single band of enzyme activity. With all of the substrates tested except L-leucyl-L-leucyl-L-leucine, a band having anodic mobility identical with that produced by the brush border enzymes was produced by the cytoplasmic enzymes. With L-trileucine as a substrate, no overlapping band was produced. This band in the cytoplasmic fraction was heat sensitive, while that in the brush border fraction was not. Thus it would appear that there is a single human intestinal brush border peptide hydrolase capable of hydrolysing a variety of di- and tri-peptides. This peptide hydrolases of the brush border and the cytoplasmic fraction of human intestine are distinct.

… and cellular biology, 2001

Our study shows that Myoc mutant mice are both viable and fertile. Our in vivo findings further d... more Our study shows that Myoc mutant mice are both viable and fertile. Our in vivo findings further demonstrate that Myoc is not required for normal IOP or normal ocular morphology. The lack of a discernable phenotype in both Myoc-heterozygous and Myocnull mice suggests that haploinsufficiency is not a critical mechanism for POAG in individuals with mutations in MYOC. Instead, disease-causing mutations in humans likely act by gain of function.

Nature Medicine, 2011

ADHD is a common psychiatric disorder characterized by inattention, hyperactivity and impulsivity... more ADHD is a common psychiatric disorder characterized by inattention, hyperactivity and impulsivity 1 . The involvement of dopamine in ADHD has gained considerable attention 2 . However, many ADHD susceptibility loci identified by genome-wide linkage or association studies do not contain dopamine-related genes 3-9 . This result, together with the phenotypic heterogeneity and strong heritability of ADHD, predicts the existence of diverse ADHD-associated genes and underlying mechanisms of disease.

… Technology Letters, IEEE, 1999

We describe the first demonstration of a dynamic erbium-doped fiber amplifier (EDFA) based on aut... more We describe the first demonstration of a dynamic erbium-doped fiber amplifier (EDFA) based on automatic feedback control of active gain equalizing filters. The filters are all-fiber acoustooptic tunable filters capable of generating controllable filter shapes. Wide dynamic-range gain/power control is achieved with <0.6-dB signal ripple over 30 nm in various operating conditions. We also show, by numerical simulation, an important advantage of the dynamic EDFA over a conventional EDFA in cascaded structures.

Aquaculture, 1995

Year 2 channel catfish averaging 41 g were stocked in 0.04 ha earthen ponds at the rate of 13 750... more Year 2 channel catfish averaging 41 g were stocked in 0.04 ha earthen ponds at the rate of 13 750 fish ha− 1. When daytime water temperature reached 25° C, one group of fish (four ponds per group) was placed on restricted feeding for 3 weeks during which time the fish ...