p-TypeE InAs/GaAs Quantum Dot, Dot-In-Well, and Low-Frequency Noise Properties of Infrared Photodetectors

Several types of p-doped Infrared detectors were studied. These include InAs/GaAs quantum dot (QDIP), and dots-in-well (DWELL) and split off band-based heterojunction detectors. In these structures, IR absorption leading to detection is based on valence-band inter-sublevel hole transitions. For a QDIP and DWELL, at 80 K, two response bands observed at 1.5 – 3 and 3 – 10 µm were identified as due to optical transitions from the heavy hole to spin–orbit split-off QD level and from the heavy-hole to heavy/light-hole level, respectively. Unlike the n-type with bias dependent spectral response, the p-type hole response displays a well-preserved spectral profile (independent of the applied bias) observed in both QDIP and DWELL detectors. At a response peak of ~ 5.2 µm, QDIP and DWELL exhibit an external quantum efficiency of 17 % and 9 % respectively. At elevated temperatures between 100 and ~120 K (for QDIP), 130 K (for DWELL), both QDIP and DWELL detectors exhibit a strong far-infrared or terahertz (THz) response up to 70 µm which show promising potential of p-type QDs for developing THz infrared photodetectors. Based on the dark current and noise power spectral density analysis, structural parameters such as the numbers of active layers, the surface density of QDs, and the carrier capture or relaxation rate, type of material and electric field are some of the optimization parameters identified to improve the photoconductive and dark current gain of detectors. The capture probability of DWELL is found to be more than two times higher than the corresponding QDIP. Based on the noise analysis, QDs based structures suppressed phonon scattering and enhanced carrier life time or photoconductive gain. Furthermore, in a GaAs/AlxGa1-xAs heterostructure, for a given width of AxlGa1-xAs barrier, the barrier thickness can be varied by varying the Al mole fraction x, which is referred to as a graded barrier. Grading the barrier and optimizing the emitter thickness of GaAs/AlGaAs heterostructures enhance the absorption efficiency, the escape probability and lower the dark current; hence, enhances the responsivity and specific detectivity of detectors. The two important methods (Arrhenius plot and Temperature Dependent Internal photoemission (TDIPS)) of determining detectors threshold wavelengths or band offsets were compared. For detectors with long threshold wavelength (\u3e\u3e 9.3 μm), the Arrhenius plot used to extract activation energy leads to energy values with deviation higher than ~ 10 % from the corresponding TDIPS values and results from the temperature dependent Fermi distribution tailing effect and Fowler–Nordheim tunneling current. Therefore, TDIPS or other methods, that take the temperature effects on the band offset and Fowler–Nordheim tunneling current into account, are needed for a precise band offset characterization of a long threshold wavelength detectors

Field Attractants for Pachnoda interrupta Selected by Means of GC-EAD and Single Sensillum Screening

The sorghum chafer, Pachnoda interrupta Olivier (Coleoptera: Scarabaeidae: Cetoniinae), is a key pest on sorghum, Sorghum bicolor (L.) Moench (Poaceae), in Ethiopia. At present there is a lack of efficient control methods. Trapping shows promise for reduction of the pest population, but would benefit from the development of attractive lures. To find attractants that could be used for control of P. interrupta, either by mass trapping or by monitoring as part of integrated pest management, we screened headspace collections of sorghum and the highly attractive weed Abutilon figarianum Webb (Malvaceae) for antennal activity using gas chromatograph-coupled electroantennographic detection (GC-EAD). Compounds active in GC-EAD were identified by combined gas chromatography and mass spectrometry (GC-MS). Field trapping suggested that attraction is governed by a few influential compounds, rather than specific odor blends. Synthetic sorghum and abutilon odor blends were attractive, but neither blend outperformed the previously tested attractants eugenol and methyl salicylate, of which the latter also was part of the abutilon blend. The strong influence of single compounds led us to search for novel attractive compounds, and to investigate the role of individual olfactory receptor neurons (ORNs) in the perception of kairomones. We screened the response characteristics of ORNs to 82 putative kairomones in single sensillum recordings (SSR), and found a number of key ligand candidates for specific classes of ORNs. Out of these key ligand candidates, six previously untested compounds were selected for field trapping trials: anethole, benzaldehyde, racemic 2,3-butanediol, isoamyl alcohol, methyl benzoate and methyl octanoate. The compounds were selected on the basis that they activated different classes of ORNs, thus allowing us to test potential kairomones that activate large non-overlapping populations of the peripheral olfactory system, while avoiding redundant multiple activations of the same ORN type. Field trapping results revealed that racemic 2,3-butanediol is a powerful novel attractant for P. interrupta

The global burden of cancer attributable to risk factors, 2010-19 : a systematic analysis for the Global Burden of Disease Study 2019

Background Understanding the magnitude of cancer burden attributable to potentially modifiable risk factors is crucial for development of effective prevention and mitigation strategies. We analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 to inform cancer control planning efforts globally. Methods The GBD 2019 comparative risk assessment framework was used to estimate cancer burden attributable to behavioural, environmental and occupational, and metabolic risk factors. A total of 82 risk-outcome pairs were included on the basis of the World Cancer Research Fund criteria. Estimated cancer deaths and disability-adjusted life-years (DALYs) in 2019 and change in these measures between 2010 and 2019 are presented. Findings Globally, in 2019, the risk factors included in this analysis accounted for 4.45 million (95% uncertainty interval 4.01-4.94) deaths and 105 million (95.0-116) DALYs for both sexes combined, representing 44.4% (41.3-48.4) of all cancer deaths and 42.0% (39.1-45.6) of all DALYs. There were 2.88 million (2.60-3.18) risk-attributable cancer deaths in males (50.6% [47.8-54.1] of all male cancer deaths) and 1.58 million (1.36-1.84) risk-attributable cancer deaths in females (36.3% [32.5-41.3] of all female cancer deaths). The leading risk factors at the most detailed level globally for risk-attributable cancer deaths and DALYs in 2019 for both sexes combined were smoking, followed by alcohol use and high BMI. Risk-attributable cancer burden varied by world region and Socio-demographic Index (SDI), with smoking, unsafe sex, and alcohol use being the three leading risk factors for risk-attributable cancer DALYs in low SDI locations in 2019, whereas DALYs in high SDI locations mirrored the top three global risk factor rankings. From 2010 to 2019, global risk-attributable cancer deaths increased by 20.4% (12.6-28.4) and DALYs by 16.8% (8.8-25.0), with the greatest percentage increase in metabolic risks (34.7% [27.9-42.8] and 33.3% [25.8-42.0]). Interpretation The leading risk factors contributing to global cancer burden in 2019 were behavioural, whereas metabolic risk factors saw the largest increases between 2010 and 2019. Reducing exposure to these modifiable risk factors would decrease cancer mortality and DALY rates worldwide, and policies should be tailored appropriately to local cancer risk factor burden. Copyright (C) 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license.Peer reviewe

A multicolor, broadband (5-20μm), quaternary-capped InAs/GaAs quantum dot infrared photodetector

Polarization-resolved resonant fluorescence of a single semiconductor quantum dot Appl. Phys. Lett. 101, 251118 (2012) Optical cavity efficacy and lasing of focused ion beam milled GaN/InGaN micropillars J. Appl. Phys. 112, 113516 (2012) Competitive carrier interactions influencing the emission dynamics of GaAsSb-capped InAs quantum dots Appl. Phys. Lett. 101, 231109 (2012) Fluorescence quantum efficiency of CdSe/ZnS quantum dots embedded in biofluids: pH dependenc

Pheromone-based mating and aggregation in the Sorghum chafer, Pachnoda interrupta

Adults of the sorghum chafer, Pachnoda interrupta Olivier (Coleoptera: Scarabaeidae: Cetoniinae), form aggregations during the mating period in July, but also in October. The beetles aggregate on food sources, e.g., Acacia spp. trees or sorghum with ripe seeds, to feed and mate. During the mating season, field trapping experiments with live beetles as bait demonstrated attraction of males to unmated females, but not to mated females or males, indicating the presence of a female-emitted sex pheromone. Unmated females combined with banana (food source) attracted significantly more males and females than did unmated females alone. Other combinations of beetles with banana were not more attractive than banana alone. Thus, aggregation behavior appears to be guided by a combination of pheromone and host volatiles. Females and males were extracted with hexane during the mating period, and the extracts were compared by using GC-MS. In a field trapping experiment, 19 compounds found only in females were tested, both singly and in a mixture. Traps baited with one of the female-associated compounds, phenylacetaldehyde, caught significantly more beetles than any other treatment. However, the sex ratio of beetles caught in these traps did not differ from that of control traps and it is possible that other components may be involved in the sex pheromone signal. Furthermore, traps baited with a mixture of all 19 compounds attracted significantly fewer beetles than did phenylacetaldehyde alone

The global burden of cancer attributable to risk factors, 2010-19: a systematic analysis for the Global Burden of Disease Study 2019

Background Understanding the magnitude of cancer burden attributable to potentially modifiable risk factors is crucial for development of effective prevention and mitigation strategies. We analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 to inform cancer control planning efforts globally. Methods The GBD 2019 comparative risk assessment framework was used to estimate cancer burden attributable to behavioural, environmental and occupational, and metabolic risk factors. A total of 82 risk-outcome pairs were included on the basis of the World Cancer Research Fund criteria. Estimated cancer deaths and disability-adjusted life-years (DALYs) in 2019 and change in these measures between 2010 and 2019 are presented. Findings Globally, in 2019, the risk factors included in this analysis accounted for 4.45 million (95% uncertainty interval 4.01-4.94) deaths and 105 million (95.0-116) DALYs for both sexes combined, representing 44.4% (41.3-48.4) of all cancer deaths and 42.0% (39.1-45.6) of all DALYs. There were 2.88 million (2.60-3.18) risk-attributable cancer deaths in males (50.6% 47.8-54.1] of all male cancer deaths) and 1.58 million (1.36-1.84) risk-attributable cancer deaths in females (36.3% 32.5-41.3] of all female cancer deaths). The leading risk factors at the most detailed level globally for risk-attributable cancer deaths and DALYs in 2019 for both sexes combined were smoking, followed by alcohol use and high BMI. Risk-attributable cancer burden varied by world region and Socio-demographic Index (SDI), with smoking, unsafe sex, and alcohol use being the three leading risk factors for risk-attributable cancer DALYs in low SDI locations in 2019, whereas DALYs in high SDI locations mirrored the top three global risk factor rankings. From 2010 to 2019, global risk-attributable cancer deaths increased by 20.4% (12.6-28.4) and DALYs by 16.8% (8.8-25.0), with the greatest percentage increase in metabolic risks (34.7% 27.9-42.8] and 33.3% 25.8-42.0]). Interpretation The leading risk factors contributing to global cancer burden in 2019 were behavioural, whereas metabolic risk factors saw the largest increases between 2010 and 2019. Reducing exposure to these modifiable risk factors would decrease cancer mortality and DALY rates worldwide, and policies should be tailored appropriately to local cancer risk factor burden. Copyright (C) 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license