Kestrel Aeronautics: KA-Ranger

As combat environments continue to evolve, there is a growing need for dedicated aircraft to provide close air support to ground forces. In response to the 2021 AIAA Undergraduate Team Aircraft Design Competition RFP, Kestrel Aeronautics developed the KA-Ranger, an affordable, light attack aircraft to operate from austere fields and replace current helicopters in close air support missions. The design must accomplish an attack mission with full weapons payload, cruise for 200 nmi at an altitude ≥10,000 ft, and loiter 4 hours. It must also complete a long-range ferry mission of at least 900 nmi range at 60% payload, cruising at an altitude ≥18,000 ft. Both missions require reserves for an additional 3,000 ft climb and 45 minute loiter. A survey of current attack aircraft yielded the initial design including a turboprop engine, low mounted rectangular wings, conventional tail, and retractable tricycle landing gear. The aircraft weighs approximately 12,000 lbf with two crew members, an integrated gun, and 3,000 lbf of externally mounted armament. Current design activities include material selection, detailed structural design, weapon and fuel placement with stability analysis, drag assessment, and power analysis to confirm the KA Ranger’s flight performance

Metal-Age maritime culture at Jareng Bori rockshelter, Pantar Island, eastern Indonesia

The archaeological record of Wallacea remains exceptionally fragmentary. This is especially the case for late Holocene human occupation of the region when lifestyle and culture in marginal island environments is relatively unknown. Here we report on the archaeology of Jareng Bori rockshelter, a Metal-Age site spanning c. 1800 cal. BP up to the late historic period and situated on the eastern coast of Pantar Island in the Lesser Sunda Islands of eastern Indonesia. We use osteoarchaeological (human and vertebrate remains), invertebrate zooarchaeological (crustacean and molluscan remains), technological (lithics, shell, and pottery) and chemical sourcing (obsidian and metal) datasets to discuss networking, migration, and human subsistence strategies during this recent period of history. While some communities were no doubt living in open village settlements where they were producing pottery, the data indicate that aspects of maritime life-ways continued much as in earlier Pleistocene settlements, with people using rockshelters like Jareng Bori to pursue a range of subsistence activities focused on the shoreline. Shellfishing of rocky and reef intertidal species and fishing for mostly small herbivorous and omnivorous fishes was practised, while domestic animals only appear in the late historic period. Wider regional cultural interactions and networking are epitomized by obsidian exchange, dental modification practices, and pottery decorations, while lithic analyses indicates continuity of stone tool technology up until recent times

Attention Reshapes Center-Surround Receptive Field Structure in Macaque Cortical Area MT

Directing spatial attention to a location inside the classical receptive field (cRF) of a neuron in macaque medial temporal area (MT) shifts the center of the cRF toward the attended location. Here we investigate the influence of spatial attention on the profile of the inhibitory surround present in many MT neurons. Two monkeys attended to the fixation point or to 1 of 2 random dot patterns (RDPs) placed inside or next to the cRF, whereas a third RDP (the probe) was briefly presented in quick succession across the cRF and surround. The probe presentation responses were used to compute a map of the excitatory receptive field and its inhibitory surround. Attention systematically reshapes the receptive field profile, independently shifting both center and surround toward the attended location. Furthermore, cRF size is changed as a function of relative distance to the attentional focus: attention inside the cRF shrinks it, whereas directing attention next to the cRF expands it. In addition, we find systematic changes in surround inhibition and cRF amplitude. This nonmultiplicative push–pull modulation of the receptive field's center-surround structure optimizes processing at and near the attentional focus to strengthen the representation of the attended stimulus while reducing influences from distractors

Predicting richness and composition in mountain insect communities at high resolution: a new test of the SESAM framework

Aim The aim of this study was to test different modelling approaches, including a new framework, for predicting the spatial distribution of richness and composition of two insect groups. Location The western Swiss Alps. Methods We compared two community modelling approaches: the classical method of stacking binary prediction obtained fromindividual species distribution models (binary stacked species distribution models, bS-SDMs), and various implementations of a recent framework (spatially explicit species assemblage modelling, SESAM) based on four steps that integrate the different drivers of the assembly process in a unique modelling procedure. We used: (1) five methods to create bS-SDM predictions; (2) two approaches for predicting species richness, by summing individual SDM probabilities or by modelling the number of species (i.e. richness) directly; and (3) five different biotic rules based either on ranking probabilities from SDMs or on community co-occurrence patterns. Combining these various options resulted in 47 implementations for each taxon. Results Species richness of the two taxonomic groups was predicted with good accuracy overall, and in most cases bS-SDM did not produce a biased prediction exceeding the actual number of species in each unit. In the prediction of community composition bS-SDM often also yielded the best evaluation score. In the case of poor performance of bS-SDM (i.e. when bS-SDM overestimated the prediction of richness) the SESAM framework improved predictions of species composition. Main conclusions Our results differed from previous findings using community-level models. First, we show that overprediction of richness by bS-SDM is not a general rule, thus highlighting the relevance of producing good individual SDMs to capture the ecological filters that are important for the assembly process. Second, we confirm the potential of SESAM when richness is overpredicted by bS-SDM; limiting the number of species for each unit and applying biotic rules (here using the ranking of SDM probabilities) can improve predictions of species compositio

Complex Feeding Tracks of the Sessile Herbivorous Insect Ophiomyia maura as a Function of the Defense against Insect Parasitoids

Because insect herbivores generally suffer from high mortality due to their natural enemies, reducing the risk of being located by natural enemies is of critical importance for them, forcing them to develop a variety of defensive measures. Larvae of leaf-mining insects lead a sedentary life inside a leaf and make conspicuous feeding tracks called mines, exposing themselves to the potential risk of parasitism. We investigated the defense strategy of the linear leafminer Ophiomyia maura Meigen (Diptera: Agromyzidae), by focusing on its mining patterns. We examined whether the leafminer could reduce the risk of being parasitized (1) by making cross structures in the inner area of a leaf to deter parasitoids from tracking the mines due to complex pathways, and (2) by mining along the edge of a leaf to hinder visually searching parasitoids from finding mined leaves due to effective background matching of the mined leaves among intact leaves. We quantified fractal dimension as mine complexity and area of mine in the inner area of the leaf as interior mine density for each sample mine, and analyzed whether these mine traits affected the susceptibility of O. maura to parasitism. Our results have shown that an increase in mine complexity with the development of occupying larvae decreases the probability of being parasitized, while interior mine density has no influence on parasitism. These results suggest that the larval development increases the host defense ability through increasing mine complexity. Thus the feeding pattern of these sessile insects has a defensive function by reducing the risk of parasitism

Attitudes and perceptions of pregnant women towards the use of Anti-Retroviral Therapy in Nigeria

Background Mother-to-child transmission of Human Immunodeficiency Virus continues to be a major problem in Nigeria. Despite several initiatives, the number of infected pregnant women receiving Anti-Retroviral Therapy to prevent Mother-to-child transmission of the virus remains low in Nigeria. Evidence suggests that attitudes and perceptions of the pregnant women influence their use of Anti-Retroviral Therapy. Aim To understand the attitudes and perceptions of Human Immunodeficiency Virus   infected pregnant women towards the use of Anti-Retroviral Therapy for prevention of mother-to-child transmission in Nigeria. Method Twenty four Human Immunodeficiency Virus infected pregnant women were purposively selected from antenatal clinics. Women’s attitudes and perceptions towards the use of Anti-Retroviral Therapy were explored using semi-structured in-depth interviews conducted in May/June 2016. All interviews were recorded, transcribed and analysed using thematic approach. Findings Overall, participants reflected a positive attitude about using Anti-Retroviral Therapy to prevent mother-to-child transmission and perceived the treatment as beneficial. The main themes identified included: perceived benefits of Anti-Retroviral Therapy; barriers to using Anti-Retroviral Therapy; threat from the susceptibility to the illness and the severity; perceived roles in treatment; and the negative behaviours of healthcare providers. Conclusion The findings provide useful insights to inform Nigeria’s health policies on Anti-Retroviral Therapy. There is a need to educate the women on the benefits of the treatment as well as how they can cope with side effects and the daily regimen of the therapy during pregnancy. The findings also indicate the need for training healthcare providers on facilitative patient-provider relationship

Gender and sexual orientation differences in cognition across adulthood : age is kinder to women than to men regardless of sexual orientation

Despite some evidence of greater age-related deterioration of the brain in males than in females, gender differences in rates of cognitive aging have proved inconsistent. The present study employed web-based methodology to collect data from people aged 20-65 years (109,612 men; 88,509 women). As expected, men outperformed women on tests of mental rotation and line angle judgment, whereas women outperformed men on tests of category fluency and object location memory. Performance on all tests declined with age but significantly more so for men than for women. Heterosexuals of each gender generally outperformed bisexuals and homosexuals on tests where that gender was superior; however, there were no clear interactions between age and sexual orientation for either gender. At least for these particular tests from young adulthood to retirement, age is kinder to women than to men, but treats heterosexuals, bisexuals, and homosexuals just the same

Engineering the isobutanol biosynthetic pathway in Escherichia coli by comparison of three aldehyde reductase/alcohol dehydrogenase genes

Biofuels synthesized from renewable resources are of increasing interest because of global energy and environmental problems. We have previously demonstrated production of higher alcohols from Escherichia coli using a 2-keto acid-based pathway. Here, we have compared the effect of various alcohol dehydrogenases (ADH) for the last step of the isobutanol production. E. coli has the yqhD gene which encodes a broad-range ADH. Isobutanol production significantly decreased with the deletion of yqhD, suggesting that the yqhD gene on the genome contributed to isobutanol production. The adh genes of two bacteria and one yeast were also compared in E. coli harboring the isobutanol synthesis pathway. Overexpression of yqhD or adhA in E. coli showed better production than ADH2, a result confirmed by activity measurements with isobutyraldehyde