We conducted a cross-sectional investigation to identify evidence of a potential modifying effect... more We conducted a cross-sectional investigation to identify evidence of a potential modifying effect of chromosomally integrated human herpes virus 6 (ciHHV-6) on human immunodeficiency virus (HIV) disease progression and/or severity. ciHHV-6 was identified by detecting HHV-6 DNA in hair follicle specimens of 439 subjects. There was no statistically significant relationship between the presence of ciHHV-6 and HIV disease progression to acquired immunodeficiency syndrome. However, after adjusting for use of antiretroviral therapy, all subjects with ciHHV-6 had low severity HIV disease; these findings were not statistically significant. A multi-center study with a larger sample size will be needed to more precisely determine if there is an association between ciHHV-6 and low HIV disease severity.
ABSTRACT Type II superlattices (T2SLs), a system of interacting multiquantum wells, were introduc... more ABSTRACT Type II superlattices (T2SLs), a system of interacting multiquantum wells, were introduced by Nobel Laureate L. Esaki in the 1970s. Since then, this material system has drawn a lot of attention, especially for infrared detection and imaging. In recent years, the T2SL material system has experienced incredible improvements in material growth quality, device structure design, and device fabrication techniques that have elevated the performance of T2SL-based photodetectors and focal-plane arrays (FPAs) to a level comparable to state-of-the-art material systems for infrared detection and imaging, such as mercury cadmium telluride compounds. We present the current status of T2SL-based photodetectors and FPAs for imaging in different infrared regimes, from short wavelength to very long wavelength, and dual-band infrared detection and imaging, as well as the future outlook for this material system.
ABSTRACT Low-frequency noise has been studied in a mid-wavelength infrared InAs/GaSb type-II supe... more ABSTRACT Low-frequency noise has been studied in a mid-wavelength infrared InAs/GaSb type-II superlattice-based focal plane array. Low-frequency noise is observed under reverse bias but not at zero bias, even in the presence of photo-current. The magnitude of low-frequency noise was separately measured as a function of operating temperature and operation bias. The low-frequency noise is linearly correlated with the generation-recombination component of the dark current. No correlation of low-frequency noise with photo-current or diffusion dark current was found.
ABSTRACT A high performance bias-selectable mid-/long-wavelength infrared photodetector based on ... more ABSTRACT A high performance bias-selectable mid-/long-wavelength infrared photodetector based on InAs/InAs1−x Sb x type-II superlattices on GaSb substrate has been demonstrated. The mid- and long-wavelength channels' 50% cut-off wavelengths were ∼5.1 and ∼9.5 μm at 77 K. The mid-wavelength channel exhibited a quantum efficiency of 45% at 100 mV bias voltage under front-side illumination and without any anti-reflection coating. With a dark current density of 1 × 10−7 A/cm2 under 100 mV applied bias, the mid-wavelength channel exhibited a specific detectivity of 8.2 × 1012 cm· Hz /W at 77 K. The long-wavelength channel exhibited a quantum efficiency of 40%, a dark current density of 5.7 × 10−4 A/cm2 under −150 mV applied bias at 77 K, providing a specific detectivity value of 1.64 × 1011 cm· Hz /W.
ABSTRACT We report a bias selectable dual-band mid-wave infrared (MWIR) and long-wave infrared (L... more ABSTRACT We report a bias selectable dual-band mid-wave infrared (MWIR) and long-wave infrared (LWIR) co-located detector with 3 μm active region thickness per channel that is highly selective and can perform under high operating temperatures for the MWIR band. Under back-side illumination, a temperature evolution study of the MWIR detector's electro-optical performance found the 300 K background-limit with 2π field-of-view to be achieved below operating temperatures of 160 K, at which the temperature's 50% cutoff wavelength was 5.2 μm. The measured current reached the system limit of 0.1 pA at 110 K for 30 μm pixel-sized diodes. At 77 K, where the LWIR channel operated with a 50% cutoff wavelength at 11.2 μm, an LWIR selectivity of ˜17% was achieved in the MWIR wave band between 3 and 4.7 μm, making the detector highly selective.
ABSTRACT Very long wavelength infrared photodetectors based on InAs/InAsSb type-II superlattices ... more ABSTRACT Very long wavelength infrared photodetectors based on InAs/InAsSb type-II superlattices are demonstrated on GaSb substrate. A heterostructure photodiode was grown with 50% cut-off wavelength of 14.6 lm. At 77 K, the photodiode exhibited a peak responsivity of 4.8 A/W, corresponding to a quantum efficiency of 46% at �300mV bias voltage from front side illumination without antireflective coating. With the dark current density of 0.7 A/cm2, it provided a specific detectivity of 1.4�1010 Jones. The device performance was investigated as a function of operating temperature, revealing a very stable optical response and a background limited performance below 50K.
ABSTRACT We demonstrate the feasibility of the InAs/GaSb/AlSb type-II superlattice photodiodes op... more ABSTRACT We demonstrate the feasibility of the InAs/GaSb/AlSb type-II superlattice photodiodes operating at the short wavelength infrared regime below 3 μm. An n-i-p type-II InAs/GaSb/AlSb photodiode was grown with a designed cut-off wavelength of 2 μm on a GaSb substrate. At 150 K, the photodiode exhibited a dark current density of 5.6 × 10−8 A/cm2 and a front-side-illuminated quantum efficiency of 40.3%, providing an associated shot noise detectivity of 1.0 × 1013 Jones. The uncooled photodiode showed a dark current density of 2.2 × 10−3 A/cm2 and a quantum efficiency of 41.5%, resulting in a detectivity of 1.7 × 1010 Jones.
International Conference on Communication Software and Networks, 2010
In this paper, we propose a novel approach for the optimal communication spanning tree (OCST) pro... more In this paper, we propose a novel approach for the optimal communication spanning tree (OCST) problem. Our algorithm is based on the Particle Swarm Optimization (PSO) technique and take account into node biased encoding (NBE) scheme to find nearly optimal solution. The new algorithm can achieve a result that is better than known heuristic algorithms do, as verified by a set of public benchmark problem instances.
International Conference on Information Engineering and Computer Science, 2009
In this paper, we study the problem of graph coloring and propose a novel particle swarm optimiza... more In this paper, we study the problem of graph coloring and propose a novel particle swarm optimization (PSO) algorithm for it. We use the PSO evolutionary progress to improve a simple deterministic greedy algorithm. The new algorithm can achieve a result that is better than known heuristic algorithms do, as verified by an extensive simulation study.
2008 IEEE International Conference on e-Business Engineering, 2008
Nowadays, with the wide range of data increased incredibly over the years, extracting and integra... more Nowadays, with the wide range of data increased incredibly over the years, extracting and integrating useful data from multiple information sources still has to face significant challenges in semantically integrating heterogeneous sources to data warehouse. Within the scope of this paper, a semantically coupling of a metamodel with an ontology will be applied, describing - at high abstraction levels -
2004 IEEE International Conference on Communications (IEEE Cat. No.04CH37577), 2004
In wireless data communications, it has been realized that by adapting the transmit power and rat... more In wireless data communications, it has been realized that by adapting the transmit power and rate, not only to the channel conditions, but also to higher layer parameters, such as the buffer occupancy and data arrival statistics, the system performance can be significantly improved. However, most of the existing approaches deal only with single user scenarios. In this paper, we
We conducted a cross-sectional investigation to identify evidence of a potential modifying effect... more We conducted a cross-sectional investigation to identify evidence of a potential modifying effect of chromosomally integrated human herpes virus 6 (ciHHV-6) on human immunodeficiency virus (HIV) disease progression and/or severity. ciHHV-6 was identified by detecting HHV-6 DNA in hair follicle specimens of 439 subjects. There was no statistically significant relationship between the presence of ciHHV-6 and HIV disease progression to acquired immunodeficiency syndrome. However, after adjusting for use of antiretroviral therapy, all subjects with ciHHV-6 had low severity HIV disease; these findings were not statistically significant. A multi-center study with a larger sample size will be needed to more precisely determine if there is an association between ciHHV-6 and low HIV disease severity.
ABSTRACT Type II superlattices (T2SLs), a system of interacting multiquantum wells, were introduc... more ABSTRACT Type II superlattices (T2SLs), a system of interacting multiquantum wells, were introduced by Nobel Laureate L. Esaki in the 1970s. Since then, this material system has drawn a lot of attention, especially for infrared detection and imaging. In recent years, the T2SL material system has experienced incredible improvements in material growth quality, device structure design, and device fabrication techniques that have elevated the performance of T2SL-based photodetectors and focal-plane arrays (FPAs) to a level comparable to state-of-the-art material systems for infrared detection and imaging, such as mercury cadmium telluride compounds. We present the current status of T2SL-based photodetectors and FPAs for imaging in different infrared regimes, from short wavelength to very long wavelength, and dual-band infrared detection and imaging, as well as the future outlook for this material system.
ABSTRACT Low-frequency noise has been studied in a mid-wavelength infrared InAs/GaSb type-II supe... more ABSTRACT Low-frequency noise has been studied in a mid-wavelength infrared InAs/GaSb type-II superlattice-based focal plane array. Low-frequency noise is observed under reverse bias but not at zero bias, even in the presence of photo-current. The magnitude of low-frequency noise was separately measured as a function of operating temperature and operation bias. The low-frequency noise is linearly correlated with the generation-recombination component of the dark current. No correlation of low-frequency noise with photo-current or diffusion dark current was found.
ABSTRACT A high performance bias-selectable mid-/long-wavelength infrared photodetector based on ... more ABSTRACT A high performance bias-selectable mid-/long-wavelength infrared photodetector based on InAs/InAs1−x Sb x type-II superlattices on GaSb substrate has been demonstrated. The mid- and long-wavelength channels' 50% cut-off wavelengths were ∼5.1 and ∼9.5 μm at 77 K. The mid-wavelength channel exhibited a quantum efficiency of 45% at 100 mV bias voltage under front-side illumination and without any anti-reflection coating. With a dark current density of 1 × 10−7 A/cm2 under 100 mV applied bias, the mid-wavelength channel exhibited a specific detectivity of 8.2 × 1012 cm· Hz /W at 77 K. The long-wavelength channel exhibited a quantum efficiency of 40%, a dark current density of 5.7 × 10−4 A/cm2 under −150 mV applied bias at 77 K, providing a specific detectivity value of 1.64 × 1011 cm· Hz /W.
ABSTRACT We report a bias selectable dual-band mid-wave infrared (MWIR) and long-wave infrared (L... more ABSTRACT We report a bias selectable dual-band mid-wave infrared (MWIR) and long-wave infrared (LWIR) co-located detector with 3 μm active region thickness per channel that is highly selective and can perform under high operating temperatures for the MWIR band. Under back-side illumination, a temperature evolution study of the MWIR detector's electro-optical performance found the 300 K background-limit with 2π field-of-view to be achieved below operating temperatures of 160 K, at which the temperature's 50% cutoff wavelength was 5.2 μm. The measured current reached the system limit of 0.1 pA at 110 K for 30 μm pixel-sized diodes. At 77 K, where the LWIR channel operated with a 50% cutoff wavelength at 11.2 μm, an LWIR selectivity of ˜17% was achieved in the MWIR wave band between 3 and 4.7 μm, making the detector highly selective.
ABSTRACT Very long wavelength infrared photodetectors based on InAs/InAsSb type-II superlattices ... more ABSTRACT Very long wavelength infrared photodetectors based on InAs/InAsSb type-II superlattices are demonstrated on GaSb substrate. A heterostructure photodiode was grown with 50% cut-off wavelength of 14.6 lm. At 77 K, the photodiode exhibited a peak responsivity of 4.8 A/W, corresponding to a quantum efficiency of 46% at �300mV bias voltage from front side illumination without antireflective coating. With the dark current density of 0.7 A/cm2, it provided a specific detectivity of 1.4�1010 Jones. The device performance was investigated as a function of operating temperature, revealing a very stable optical response and a background limited performance below 50K.
ABSTRACT We demonstrate the feasibility of the InAs/GaSb/AlSb type-II superlattice photodiodes op... more ABSTRACT We demonstrate the feasibility of the InAs/GaSb/AlSb type-II superlattice photodiodes operating at the short wavelength infrared regime below 3 μm. An n-i-p type-II InAs/GaSb/AlSb photodiode was grown with a designed cut-off wavelength of 2 μm on a GaSb substrate. At 150 K, the photodiode exhibited a dark current density of 5.6 × 10−8 A/cm2 and a front-side-illuminated quantum efficiency of 40.3%, providing an associated shot noise detectivity of 1.0 × 1013 Jones. The uncooled photodiode showed a dark current density of 2.2 × 10−3 A/cm2 and a quantum efficiency of 41.5%, resulting in a detectivity of 1.7 × 1010 Jones.
International Conference on Communication Software and Networks, 2010
In this paper, we propose a novel approach for the optimal communication spanning tree (OCST) pro... more In this paper, we propose a novel approach for the optimal communication spanning tree (OCST) problem. Our algorithm is based on the Particle Swarm Optimization (PSO) technique and take account into node biased encoding (NBE) scheme to find nearly optimal solution. The new algorithm can achieve a result that is better than known heuristic algorithms do, as verified by a set of public benchmark problem instances.
International Conference on Information Engineering and Computer Science, 2009
In this paper, we study the problem of graph coloring and propose a novel particle swarm optimiza... more In this paper, we study the problem of graph coloring and propose a novel particle swarm optimization (PSO) algorithm for it. We use the PSO evolutionary progress to improve a simple deterministic greedy algorithm. The new algorithm can achieve a result that is better than known heuristic algorithms do, as verified by an extensive simulation study.
2008 IEEE International Conference on e-Business Engineering, 2008
Nowadays, with the wide range of data increased incredibly over the years, extracting and integra... more Nowadays, with the wide range of data increased incredibly over the years, extracting and integrating useful data from multiple information sources still has to face significant challenges in semantically integrating heterogeneous sources to data warehouse. Within the scope of this paper, a semantically coupling of a metamodel with an ontology will be applied, describing - at high abstraction levels -
2004 IEEE International Conference on Communications (IEEE Cat. No.04CH37577), 2004
In wireless data communications, it has been realized that by adapting the transmit power and rat... more In wireless data communications, it has been realized that by adapting the transmit power and rate, not only to the channel conditions, but also to higher layer parameters, such as the buffer occupancy and data arrival statistics, the system performance can be significantly improved. However, most of the existing approaches deal only with single user scenarios. In this paper, we
Uploads