QWIPs, SLS, Landsat and the International Space Station

In 1988 DARPA provided funding to NASAs Goddard Space Flight Center to support the development of GaAs Quantum Well Infrared Photodetectors (QWIP). The goal was to make a single element photodetector that might be expandable to a two-dimensional array format. Ultimately, this led to the development of a 128 x 128 element array in collaboration with AT&T Bell Labs and Rockwell Science Center in 1990. We continued to develop numerous generations of QWIP arrays most recently resulting in the multi-QWIP focal plane for the NASA-US Geological Survey (USGS) Landsat 8 mission launched in 2013 and a similar instrument on the Landsat 9 mission to be launched in 2020. Toward the end of the Landsat 8 QWIP-based Thermal Infrared Sensor (TIRS) instrument the potential of the newly developed Strained Layer Superlattice (SLS) detector array technology became of great interest to NASA for three primary reasons: 1) higher operating temperature; 2) broad spectral response and; 3) higher sensitivity. We have collaborated extensively with QmagiQ, LLC and Northwestern University to further pursue and advance the SLS technology ever since we started back in 2012. In December of 2018 we launched the first SLS-based IR camera system to the International Space Station on board the Robotic Refueling Mission #3 (RRM3). This paper will describe the evolution of QWIP technology leading to the current development of SLS-based imaging systems at the Goddard Space Flight Center over the past 30 years

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

Effect of long-term treatment with aromatase inhibitor on testicular function of adult male bonnet monkeys (M. radiata)

The role/need for estrogen in regulating testicular function of adult male bonnet monkeys (M. radiata) has been investigated by dosing orally a group of five normal males 2.5 mgs of CGP 47645, a long-acting nonsteroidal aromatase inhibitor (AI), once every 5 days for over 150 days. Such treatment resulted in a 10-fold increment in nocturnal serum testosterone (T) levels, which were sustained for 85 days of treatment, and a twofold increment in basal serum T levels was present throughout the 150 days of treatment. Analysis of ejaculated semen showed a marked reduction (~90%) in sperm counts in four out of five monkeys between Days 55-85 of treatment. During this period, the motility score also was markedly reduced from a normal score of 3-5 to 0-2. Flow cytometric analysis of testicular germ cells obtained from biopsy tissue taken on Days 63 and 120 indicated a marked reduction only in elongating/elongated spermatid population (compared to Day 0 values), suggesting inhibition in spermiogenic process. Epididymal sperm maturation also seemed effected as sperm chromatin, on flow cytometric analysis for decondensability following exposure to 5 mM dithiotreitol, showed to be in a hypercondensed state. This study thus indicates that estrogen has an important role in providing normal testicular and sperm function in the primate

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

Digitally-enabled crop disorder management process based on farmer empowerment for improved outcomes : a case study from Sri Lanka

We have developed a system facilitated by a mobile artefact to effectively identify crop disorder incidents and manage them using recommended control measures. This work overcomes the limitations of the existing attempts by using digital technology to empower farmers to identify crop disorders rather than replace them with automated techniques. Our approach empowers farmers by providing the information in context for them to identify crop disorders. The developed solution can identify most of the crop disorders instantaneously, irrespective of the crop or other factors that make crop disorder identification complicated. For the rest, it provides a mechanism to carry out a manual identification with the help of subject experts. The solution was deployed among paddy farmers in Sri Lanka to understand how well this could assist them in identifying and managing crop disorders. The system was able to identify 70.8% of the crop disorder incidents reported by the farmers and provided them with the relevant control measures. Farmers’ perceptions of various usability aspects of the solution revealed that the application of agrochemicals and expenses associated with agrochemicals were significantly reduced. It was also observed that the yield quality and quantity and overall revenue have increased compared to the previous seasons

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

An unblinded, randomised phase II study of platinum-based chemotherapy with vitamin B12 and folic acid supplementation in the treatment of lung cancer with plasma homocysteine blood levels as a biomarker of severe neutropenic toxicity

BACKGROUND: Vitamin B12 and folic acid (referred to as vitamin supplementation) improves the toxicity profile of pemetrexed containing regimens. Low baseline vitamin B12 and folate levels are reflected in a raised total homocysteine level (HC). Studies have suggested that pretreatment HC levels predict neutropenia toxicity. We have tested supplementation with vitamin B12 and folate in non-pemetrexed platinum-based regimens to decrease treatment-related toxicity and looked for a correlation between toxicity and change in homocysteine levels. PATIENT AND METHOD: Eighty-three patients with advanced lung cancer and malignant mesothelioma were randomly assigned to receive platinum-based chemotherapy with (arm A) or without (arm B) vitamin B12 and folic acid supplementation. The primary end point was grade 3/4 neutropenia and death within 30 days of treatment. Secondary end points included quality of life, overall survival (OS) and the relationship between baseline and post supplementation HC levels and toxicity. RESULTS: In the intention-to-treat population, no significant difference was seen between the two groups with respect to chemotherapy-induced grade 3/4 neutropenia and death within 30 days of chemotherapy (36% vs 37%; p=0.966, emesis (2% vs 6%; p=0.9) or OS (12.3 months vs 7 months; p=0.41). There was no significant difference in survival rates by baseline HC level (p=0.9). Decrease in HC with vitamin supplementation was less frequent than expected. High baseline HC levels decreased with vitamin supplementation in only 9/36 (25%) patients (successful supplementation). Post hoc analysis showed that patients in arm A who were successfully supplemented (9/36=25%) had less neutropenic toxicity (0% vs 69%; p=0.02) compared to unsupplemented patients. CONCLUSIONS: The addition of vitamin B12 and folic acid to platinum-containing regimens did not overall improve the toxicity, quality of life or OS. Rates of grade 3/4 neutropenia at 36/37% was as predicted. Further studies to increase the rate of successful supplementation and to further test the biomarker potential of post supplementation HC levels in predicting chemotherapy-induced neutropenia in platinum-based chemotherapy are warranted. TRIAL REGISTRATION NUMBER: EudracCT 2005-002736-10 ISRCTN8734355

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