823 research outputs found

    FUNDAMENTAL AND INDUCED BIASES IN TECHNOLOGICAL CHANGE IN CENTRAL CANADIAN AGRICULTURE

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    A new procedure is developed to estimate innovation possibility frontiers and test for biases in technological change. Using data on four inputs (land, machinery, chemicals and labour) from central Canada (Ontario and Quebec) over the period 1926-1985, we find that the innovations possibilities frontier shifts neutrally over time. This is consistent with Ahmad's model of induced innovations, but is not consistent with de Janvry's application of Ahmad's model to the historical development of Argentine agriculture. Agricultural research in Canada has been conducted with the objective of developing cost minimizing technologies. Empirical support was found for this notion in the development of the innovation possibilities frontier.Innovation possibility frontier, technological change, Research and Development/Tech Change/Emerging Technologies,

    Topographical variation reduces phenological mismatch between a butterfly and its nectar source

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    © 2014, Springer International Publishing Switzerland. The timing of many biological events, including butterfly imago emergence, has advanced under climate change, with the rate of these phenological changes often differing among taxonomic groups. Such inter-taxa variability can lead to phenological mismatches. For example, the timing of a butterfly’s flight period may become misaligned with a key nectar resource, potentially increasing the extinction risk to both species. Here we fit statistical models to field data to determine how the phenology of the marbled white butterfly, Melanargia galathea, and its main nectar source, greater knapweed, Centaurea scabiosa, have changed over recent years at three sites across the UK. We also consider whether topographical diversity affects C. scabiosa’s flowering period. At our focal site, on the species’ northern range limit, we find that over a 13-year period the onset of C. scabiosa’s flowering period has become later whilst there is no obvious trend over time in the onset of M. galathea’s flight period. In recent years, butterflies have started to emerge before their key nectar source was available across most of the site. This raises the intriguing possibility that phenological mismatch could be an unrecognised determinant of range limits for some species. However, the presence of topographical diversity within the site decreased the chance of a mismatch occurring by increasing the length of the flowering period by up to 14days. We suggest that topographical diversity could be an important component in minimising phenological mismatches under future climate change

    Application of fluorescence correlation spectroscopy to study substrate binding in styrene maleic acid lipid copolymer encapsulated ABCG2

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    © 2020 The Authors ABCG2 is one of a trio of human ATP binding cassette transporters that have the ability to bind and transport a diverse array of chemical substrates out of cells. This so-called “multidrug” transport has numerous physiological consequences including effects on how drugs are absorbed into and eliminated from the body. Understanding how ABCG2 is able to interact with multiple drug substrates remains an important goal in transporter biology. Most drugs are believed to interact with ABCG2 through the hydrophobic lipid bilayer and experimental systems for ABCG2 study need to incorporate this. We have exploited styrene maleic acid to solubilise ABCG2 from HEK293T cells overexpressing the transporter, and confirmed by dynamic light scattering and fluorescence correlation spectroscopy (FCS) that this results in the extraction of SMA lipid copolymer (SMALP) particles that are uniform in size and contain a dimer of ABCG2, which is the predominant physiological state. FCS was further employed to measure the diffusion of a fluorescent ABCG2 substrate (BODIPY-prazosin) in the presence and absence of SMALP particles of purified ABCG2. Autocorrelation analysis of FCS traces enabled the mathematical separation of free BODIPY-prazosin from drug bound to ABCG2 and allowed us to show that combining SMALP extraction with FCS can be used to study specific drug: transporter interactions

    Using behavioral studies to adapt management decisions and reduce negative interactions between humans and baboons in Cape Town, South Africa

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    Understanding the behavioral ecology of wildlife that experiences negative interactions with humans and the outcome of any wildlife management intervention is essential. In the Cape Peninsula, South Africa, chacma baboons (Papio ursinus) search for anthropogenic food sources in both urban and agricultural areas. In response, the city of Cape Town and private farmers employ “rangers” to keep baboons within the Table Mountain National Park. In this study, we investigated the success of rangers' intervention in keeping baboons in their natural habitat. Based on our findings in year one, we recommended adjustments to the rangers' management strategy in year two. We recommended improved consensus of actions toward baboons (that is, when/where to herd them), and the construction of a baboon-proof fence around one of the farms that provided a corridor to urban areas. During the 2 months following recommendations, these interventions combined resulted in a significant reduction in the time baboons spent in both urban and agricultural land. Our case study illustrates the importance of integrating research findings into ongoing management actions to improve both human livelihoods and baboon conservation through an adaptive management framework. We expect similar approaches to be beneficial in a wide range of species and contexts

    Changes in metabolic toxicity after switching from stavudine/didanosine to tenofovir/lamivudine—a Staccato trial substudy

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    Objectives Stavudine is widely used in Thailand and is associated with mitochondrial toxicity. Here, we evaluated the effect of switching from stavudine/didanosine to tenofovir/lamivudine on measures of metabolic and mitochondrial toxicity in Thai patients. Methods Thirty-five Thai patients with full HIV RNA suppression were switched from stavudine/didanosine to tenofovir/lamivudine while receiving saquinavir/ritonavir 1600/100 mg once daily. Patients were assessed at the time of switch and 24 and 48 weeks after for lipids, liver enzymes, lactate, mitochondrial DNA content and limb/total fat mass by dual energy X-ray absorptiometry (DEXA) scanning. Results Forty-eight weeks after the switch, there were significant reductions in lipids and lactate, but no change in liver enzymes. There was reversal of lipoatrophy, as shown by rises in limb fat mass (+0.38 kg, P = 0.006) and total fat mass (+0.69 kg, P = 0.02) on DEXA scan. Patients perceived weight improvement, but did not report reversal of lipoatrophy of individual body parts. The mitochondrial DNA/nuclear DNA ratio rose (+1.06, P < 0.0001). Conclusions After the nucleoside reverse transcriptase inhibitor switch, reversal of mitochondrial toxicity was consistent with switch studies of mainly Caucasian patients, although the peripheral mononuclear cell mitochondrial DNA rise exceeded previous report

    A novel Online-to-Offline (O2O) model for pre-exposure prophylaxis and HIV testing scale up

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    Introduction: PrEP awareness and uptake among men who have sex with men (MSM) and transgender women (TG) in Thailand remains low. Finding ways to increase HIV testing and PrEP uptake among high-risk groups is a critical priority. This study evaluates the effect of a novel Adam’s Love Online-to-Offline (O2O) model on PrEP and HIV testing uptake among Thai MSM and TG and identifies factors associated with PrEP uptake

    Factors affecting consistency and accuracy in identifying modern macroperforate planktonic foraminifera

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    Planktonic foraminifera are widely used in biostratigraphic, palaeoceanographic and evolutionary studies, but the strength of many study conclusions could be weakened if taxonomic identifications are not reproducible by different workers. In this study, to assess the relative importance of a range of possible reasons for among-worker disagreement in identification, 100 specimens of 26 species of macroperforate planktonic foraminifera were selected from a core-top site in the subtropical Pacific Ocean. Twenty-three scientists at different career stages – including some with only a few days experience of planktonic foraminifera – were asked to identify each specimen to species level, and to indicate their confidence in each identification. The participants were provided with a species list and had access to additional reference materials. We use generalised linear mixed-effects models to test the relevance of three sets of factors in identification accuracy: participant-level characteristics (including experience), species-level characteristics (including a participant’s knowledge of the species) and specimen-level characteristics (size, confidence in identification). The 19 less experienced scientists achieve a median accuracy of 57 %, which rises to 75 % for specimens they are confident in. For the 4 most experienced participants, overall accuracy is 79 %, rising to 93 % when they are confident. To obtain maximum comparability and ease of analysis, everyone used a standard microscope with only 35× magnification, and each specimen was studied in isolation. Consequently, these data provide a lower limit for an estimate of consistency. Importantly, participants could largely predict whether their identifications were correct or incorrect: their own assessments of specimen-level confidence and of their previous knowledge of species concepts were the strongest predictors of accuracy

    Analysis of sequence divergence in mammalian abcgs predicts a structural network of residues that underlies functional divergence

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    © 2021 by the authors. Licensee MDPI, Basel, Switzerland. The five members of the mammalian G subfamily of ATP-binding cassette transporters differ greatly in their substrate specificity. Four members of the subfamily are important in lipid transport and the wide substrate specificity of one of the members, ABCG2, is of significance due to its role in multidrug resistance. To explore the origin of substrate selectivity in members 1, 2, 4, 5 and 8 of this subfamily, we have analysed the differences in conservation between members in a multiple sequence alignment of ABCG sequences from mammals. Mapping sets of residues with similar patterns of conservation onto the resolved 3D structure of ABCG2 reveals possible explanations for differences in function, via a connected network of residues from the cytoplasmic to transmembrane domains. In ABCG2, this network of residues may confer extra conformational flexibility, enabling it to transport a wider array of substrates

    Development of a decision support tool to facilitate primary care management of patients with abnormal liver function tests without clinically apparent liver disease [HTA03/38/02]. Abnormal Liver Function Investigations Evaluation (ALFIE)

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    Liver function tests (LFTs) are routinely performed in primary care, and are often the gateway to further invasive and/or expensive investigations. Little is known of the consequences in people with an initial abnormal liver function (ALF) test in primary care and with no obvious liver disease. Further investigations may be dangerous for the patient and expensive for Health Services. The aims of this study are to determine the natural history of abnormalities in LFTs before overt liver disease presents in the population and identify those who require minimal further investigations with the potential for reduction in NHS costs
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