Growth and characteristics of type-II InAs/GaSb superlattice-based detectors

We report on growth and device performance of infrared photodetectors based on type II InAs/Ga(In)Sb strain layer superlattices (SLs) using the complementary barrier infrared detector (CBIRD) design. The unipolar barriers on either side of the absorber in the CBIRD design in combination with the type-II InAs/GaSb superlattice material system are expected to outperform traditional III-V LWIR imaging technologies and offer significant advantages over the conventional II-VI material based FPAs. The innovative design of CBIRDS, low defect density material growth, and robust fabrication processes have resulted in the development of high performance long wave infrared (LWIR) focal plane arrays at JPL

Resolution of severe hyponatraemia is associated with improved survival in patients with cancer

© Balachandran et al.Background: Hyponatraemia is a common finding in patients with cancer, and has been shown to be associated with poor prognosis in different settings. We have analysed the impact of severe hyponatraemia in patients with cancer. Methods: A retrospective review of all patients admitted to a specialist cancer hospital with a plasma sodium of less than 115 mmol/l and a diagnosis of malignancy was undertaken. Patient and tumour characteristics were analysed as well as impact of hyponatraemia management on overall survival and number of lines of cancer treatment received. Results: 57 patients were identified. 84% had advanced Stage 3 or 4 cancer and approximately 85% with data available had symptoms attributable to hyponatraemia. Mean length of hospital stay was 12 days, and overall survival (OS) was 5.1 months. Plasma sodium level corrected in 56% of patients and here OS was 13.6 months compared to 16 days in those whose sodium did not correct (p < 0.001). Those whose sodium corrected were more likely to receive further lines of anti-cancer treatment. Conclusions: Severe hyponatraemia in cancer is associated with very poor survival, but correction of the sodium level leads to additional treatment and significantly greater overall survival (although it is not possible to determine if this is due to specific therapy of the hyponatraemia or the resolving hyponatraemia reflects an improvement in the clinical condition). Aggressive treatment of hyponatraemia may allow more anti-cancer treatment and improve survival

Long-wavelength PTSI infrared detectors and method of fabrication thereof

Extended cutoff wavelengths of PtSi Schottky infrared detectors in the long wavelength infrared (LWIR) regime have been demonstrated for the first time. This result was achieved by incorporating a 1-nm-thick p+ doping spike at the PtSi/Si interface. The extended cutoff wavelengths resulted from the combined effects of an increased electric field near the silicide/Si interface due to the p+ doping spike and the Schottky image force. The p+ doping spikes were grown by molecular beam epitaxy at 450 degrees Celsius using elemental boron as the dopant source, with doping concentrations ranging from 1.times.10.sup.19 to 1.times.10.sup.21 cm.sup.-3. The cutoff wavelengths were shown to increase with increasing doping concentrations of the p+ spikes

A prospective observational study of on-treatment plasma homocysteine levels as a biomarker of toxicity, depression and vitamin supplementation lead-in time pre pemetrexed, in patients with non-small cell lung cancer and malignant mesothelioma

OBJECTIVES: Vitamin supplementation reduces pemetrexed toxicity. Raised plasma homocysteine reflects deficiency in vitamin B12 and folate, and is suppressed by supplementation. This observational study of 112 patients receiving pemetrexed-based chemotherapy assessed homocysteine levels after 3 weeks of vitamin supplementation, hypothesising high levels would correlate with ongoing deficiency, thus increased toxicity. MATERIAL AND METHODS: Primary endpoint was the composite of proportion of patients with treatment delay/ dose reduction/ drug change or hospitalisation during the first six weeks of chemotherapy, comparing those with normal plasma homocysteine (successfully supplemented, SS) and those with high homocysteine (unsuccessfully supplemented, USS). Secondary endpoints included toxicity and analyses for depression. Post-hoc analysis examined correlation between interval of vitamin and folate supplementation and pemetrexed on primary endpoint and grade 3-4 toxicities. RESULTS: Eighty-four patients (84%) were successfully supplemented (SS group). The proportion of patients undergoing a treatment delay/ dose reduction/ drug change or hospitalisation in SS group was 44.0% (95% confidence interval [CI] 33.2%-55.3%) and in USS group was 18.8% (95% CI 4.0%-45.6%) (p = 0.09). Twelve percent of patients gave a past history of depression however 66% of patients had an on study Hospital Anxiety and Depression (HAD) score of >7. Supplementation status was not associated with depression. The median overall survival (OS) was 11.8 months (95% CI 8.6-16.5) in the SS group and 8.8 months (95% CI 6.6-16.2) in the US group (p = 0.5). The number of days (<7 or ≥ 7 days) between vitamin B12 and folate initiation and pemetrexed administration, had no effect on the primary endpoint and grade 3-4 toxicities. CONCLUSION: On-treatment homocysteine levels were not a biomarker of toxicity or depression. Standard vitamin supplementation is adequate in the majority of patients receiving pemetrexed. High HAD score were noted in this population giving an opportunity for mental health intervention. The lead-in time for vitamin supplementation can be short

15-micro-m 128 x 128 GaAs/Al(x)Ga(1-x) As Quantum Well Infrared Photodetector Focal Plane Array Camera

In this paper, we discuss the development of very sensitive, very long wavelength infrared GaAs/Al(x)Ga(1-x)As quantum well infrared photodetectors (QWIP's) based on bound-to-quasi-bound intersubband transition, fabrication of random reflectors for efficient light coupling, and the demonstration of a 15 micro-m cutoff 128 x 128 focal plane array imaging camera. Excellent imagery, with a noise equivalent differential temperature (N E(delta T)) of 30 mK has been achieved

Impact of a charged neighboring particle on Förster resonance energy transfer (FRET)

Förster resonance energy transfer (FRET) is an important physical phenomenon which demands precise control over the FRET rate for its wide range of applications. Hence, enhancing the FRET rate using different techniques has been extensively studied in the literature. Research indicates that introducing additional particles to a system consisting of a donor-acceptor pair can change the behaviour of FRET in the system. One such technique is to utilize the collective oscillations of the surface electrons of a neighboring electrically-neutral metal nanoparticle (MNP). However, the perceived changes on the FRET rate between the donor and the acceptor, when the MNP carries excess electrical charges are yet unknown. In this paper, we study these changes by introducing a charged MNP, in the proximity of an excited donor and a ground state acceptor. We deploy the classical Green's tensor to express the FRET rate in the system. We consider an effective dielectric response for the MNP, which accounts for the extraneous surface charge effects. We analyze the electrical potential at the acceptor position due to the changed dipole moment of the donor molecule as a result of the electric field induced at the donor position, and obtain the FRET rate of the system. This model considers arbitrary locations and orientations of the two molecular dipole moments with regard to the position of the spherical MNP. We present the enhancement of the FRET rate, predominantly caused by both the surface plasmon excitations and the extraneous surface electrical charges carried by the neighboring MNP. We obtain the results by varying the separation distance between the molecules and the MNP, the transition frequency of the donor-acceptor pair and the size of the metallic sphere. Specifically, we demonstrate that a donor-acceptor pair placed in the vicinity of an electrically-charged Silver MNP exhibits a remarkable improvement in the FRET rate. Furthermore, the aggregate FRET enhancement is determined by other characteristics such as the location of the donor, transition frequency, separation distances and the radius of the MNP. In essence, these findings reveal an approach to realize the enhanced FRET rate in a larger span in a more controlled manner that is desirable in many FRET-based applications including spectroscopic measurements

Single Gene Deletions of Orexin, Leptin, Neuropeptide Y, and Ghrelin Do Not Appreciably Alter Food Anticipatory Activity in Mice

Timing activity to match resource availability is a widely conserved ability in nature. Scheduled feeding of a limited amount of food induces increased activity prior to feeding time in animals as diverse as fish and rodents. Typically, food anticipatory activity (FAA) involves temporally restricting unlimited food access (RF) to several hours in the middle of the light cycle, which is a time of day when rodents are not normally active. We compared this model to calorie restriction (CR), giving the mice 60% of their normal daily calorie intake at the same time each day. Measurement of body temperature and home cage behaviors suggests that the RF and CR models are very similar but CR has the advantage of a clearly defined food intake and more stable mean body temperature. Using the CR model, we then attempted to verify the published result that orexin deletion diminishes food anticipatory activity (FAA) but observed little to no diminution in the response to CR and, surprisingly, that orexin KO mice are refractory to body weight loss on a CR diet. Next we tested the orexigenic neuropeptide Y (NPY) and ghrelin and the anorexigenic hormone, leptin, using mouse mutants. NPY deletion did not alter the behavior or physiological response to CR. Leptin deletion impaired FAA in terms of some activity measures, such as walking and rearing, but did not substantially diminish hanging behavior preceding feeding time, suggesting that leptin knockout mice do anticipate daily meal time but do not manifest the full spectrum of activities that typify FAA. Ghrelin knockout mice do not have impaired FAA on a CR diet. Collectively, these results suggest that the individual hormones and neuropepetides tested do not regulate FAA by acting individually but this does not rule out the possibility of their concerted action in mediating FAA

Nutrient Sensor in the Brain Directs the Action of the Brain-Gut Axis in Drosophila

Animals can detect and consume nutritive sugars without the influence of taste. However, the identity of the taste-independent nutrient sensor and the mechanism by which animals respond to the nutritional value of sugar are unclear. Here, we report that six neurosecretory cells in the Drosophila brain that produce Diuretic hormone 44 (Dh44), a homolog of the mammalian corticotropin-releasing hormone (CRH), were specifically activated by nutritive sugars. Flies in which the activity of these neurons or the expression of Dh44 was disrupted failed to select nutritive sugars. Manipulation of the function of Dh44 receptors had a similar effect. Notably, artificial activation of Dh44 receptor-1 neurons resulted in proboscis extensions and frequent episodes of excretion. Conversely, reduced Dh44 activity led to decreased excretion. Together, these actions facilitate ingestion and digestion of nutritive foods. We propose that the Dh44 system directs the detection and consumption of nutritive sugars through a positive feedback loop

T-helper 1 versus T-helper 2 lymphocyte immunodysregulation is the central factor in genesis of Burkitt lymphoma: hypothesis

<p>Abstract</p> <p>Background</p> <p>The HIV epidemic has challenged our previous understanding of endemic Burkitt's lymphoma. Despite the strong association of Burkitt's lymphoma and HIV infection in the Developed world, and against previous postulations that the cancer is due to immunosupression among African children, the HIV epidemic in the Malaria belt has not been associated with a corresponding increase in incidence of childhood Burkitt's lymphoma. Even outside the context of HIV infection, there is substantial evidence for a strong but skewed immune response towards a TH2 response in genesis of Burkitt lymphoma.</p> <p>Presentation of the hypothesis</p> <p>Rather than a global and/or profound immunosupression, the final common pathway in genesis of Burkitt's lymphoma is the dysregulation of the immune response towards a TH2 response dominated by B-lymphocytes, and the concomitant suppression of the TH1 cell-mediated immune surveillance, driven by various viral/parasitic/bacterial infections.</p> <p>Testing the hypothesis</p> <p>Case control studies comparing TH2 and TH1 immune responses in Burkitt lymphoma of different etiological types (sporadic, HIV-related, endemic and post-transplant) to demonstrate significant dominance of TH2 immune response in presence of poor CMI response as a common factor. Immunological profiling to evaluate differences between immune states that are associated (such as recurrent Malaria infection) and those that are not associated (such as severe protein-energy malnutrition) with Burkitt lymphoma. Prospective cohorts profiling chronology of immunological events leading to Burkitt lymphoma in children with EBV infection.</p> <p>Implications of the hypothesis</p> <p>The dysregulation of the immune response may be the missing link in our understanding of Burkitt lymphomagenesis. This will provide possibilities for determination of risk and for control of development of malignancy in individuals/populations exposed to the relevant infections.</p

Food Anticipatory Activity Behavior of Mice across a Wide Range of Circadian and Non-Circadian Intervals

When rodents are fed in a limited amount during the daytime, they rapidly redistribute some of their nocturnal activity to the time preceding the delivery of food. In rats, anticipation of a daily meal has been interpreted as a circadian rhythm controlled by a food-entrained oscillator (FEO) with circadian limits to entrainment. Lesion experiments place this FEO outside of the light-entrainable circadian pacemaker in the suprachiasmatic nucleus. Mice also anticipate a fixed daily meal, but circadian limits to entrainment and anticipation of more than 2 daily meals, have not been assessed. We used a video-based behavior recognition system to quantify food anticipatory activity in mice receiving 2, 3, or 6 daily meals at intervals of 12, 8, or 4-hours (h). Individual mice were able to anticipate as many as 4 of 6 daily meals, and anticipation persisted during meal omission tests. On the 6 meal schedule, pre-prandial activity and body temperature were poorly correlated, suggesting independent regulation. Mice showed a limited ability to anticipate an 18 h feeding schedule. Finally, mice showed concurrent circadian and sub-hourly anticipation when provided with 6 small meals, at 30 minute intervals, at a fixed time of day. These results indicate that mice can anticipate feeding opportunities at a fixed time of day across a wide range of intervals not previously associated with anticipatory behavior in studies of rats. The methods described here can be exploited to determine the extent to which timing of different intervals in mice relies on common or distinct neural and molecular mechanisms