284 research outputs found

    Applying generic landscape-scale models of natural pest control to real data: Associations between crops, pests and biocontrol agents make the difference

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    Managing agricultural land to maximize the supply of natural pest control can help reduce pesticide use. Tools that are able to represent the relationship between landscape structure, field management and natural pest control can help in deciding which management practices should be used and where. However, the reliability and the predictive power of generic models of natural pest control is largely unknown. We applied an existing generic model of natural pest control potential based on landscape structure to nine sites in five European countries and tested the resulting values against field measurements of natural pest control. Subsequently, we added information on local level factors to test the possibility of improving model performance and predictive power. The results showed that there is generally little or no evidence of correlation between modeled and field-measured values of natural pest control. Moreover, we found high variability in the results, depending on the associations of crops, pests and biocontrol agents considered (e.g. Oilseed rape-Pollen beetle-Parasitoids) and on the different case studies. Factors at the local level, such as conservation tillage, had an overall positive effect on natural pest control, and their inclusion in the models typically increased their predictive power. Our results underline the importance of developing predictive models of natural pest control which are tailored towards specific associations between crops, pests and biocontrol agents, consider local level factors and are trained using field measurements. They would serve as important tools within farmers' decision making, ultimately supporting the shift toward a low-pesticide agriculture

    Controlled-NOT logic gate for phase qubits based on conditional spectroscopy

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    A controlled-NOT logic gate based on conditional spectroscopy has been demonstrated recently for a pair of superconducting flux qubits [Plantenberg et al., Nature 447, 836 (2007)]. Here we study the fidelity of this type of gate applied to a phase qubit coupled to a resonator (or a pair of capacitively coupled phase qubits). Our results show that an intrinsic fidelity of more than 99% is achievable in 45ns.Comment: 5 pages, 5 figures, To appear in Quantum Inf. Pro

    Pulsed Feedback Defers Cellular Differentiation

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    Environmental signals induce diverse cellular differentiation programs. In certain systems, cells defer differentiation for extended time periods after the signal appears, proliferating through multiple rounds of cell division before committing to a new fate. How can cells set a deferral time much longer than the cell cycle? Here we study Bacillus subtilis cells that respond to sudden nutrient limitation with multiple rounds of growth and division before differentiating into spores. A well-characterized genetic circuit controls the concentration and phosphorylation of the master regulator Spo0A, which rises to a critical concentration to initiate sporulation. However, it remains unclear how this circuit enables cells to defer sporulation for multiple cell cycles. Using quantitative time-lapse fluorescence microscopy of Spo0A dynamics in individual cells, we observed pulses of Spo0A phosphorylation at a characteristic cell cycle phase. Pulse amplitudes grew systematically and cell-autonomously over multiple cell cycles leading up to sporulation. This pulse growth required a key positive feedback loop involving the sporulation kinases, without which the deferral of sporulation became ultrasensitive to kinase expression. Thus, deferral is controlled by a pulsed positive feedback loop in which kinase expression is activated by pulses of Spo0A phosphorylation. This pulsed positive feedback architecture provides a more robust mechanism for setting deferral times than constitutive kinase expression. Finally, using mathematical modeling, we show how pulsing and time delays together enable “polyphasic” positive feedback, in which different parts of a feedback loop are active at different times. Polyphasic feedback can enable more accurate tuning of long deferral times. Together, these results suggest that Bacillus subtilis uses a pulsed positive feedback loop to implement a “timer” that operates over timescales much longer than a cell cycle

    Analysis of Five Field Event Performances at the Drake Relays by Age and Gender, 1978-2008

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    Advisor: David S. SenchinaWe analyzed gender and age differences in Drake Relays performance distances for 2 jumping (long jump and triplejump) and 3 throwing (discus, javelin, shotput) field events for 31 years (1978-2008). The top 10 performances were taken each year for 4 groups: high school (HS) boys, HS girls, college/university (C/U) men, C/U women. Our data set included 4403 performances total, because not all ages/genders competed in all events or for the same number of years. Generally, females significantly improved their jumping or throwing distances whereas males showed no improvements or significantly declined in performance. HS girls showed statistically significant improvements in all 3 of their events (discus, shotput, long jump), and C/U women showed improvements in 4 of their 5 events (discus, javelin, shotput, triplejump) and demonstrated no change in long jump performance. In comparison, HS boys showed no changes in 2 of their 3 events (discus and shotput) and significantly shorter distance in long jump, and C/U men demonstrated significantly shorter throwing or jumping distances in 4 of their 5 events (javelin, shotput, long jump, triplejump) and no change in discus. Despite the improvements in female performance distances, males threw or jumped further than females in all events for all years except for discus, where C/U women were out-throwing HS boys by 2008. As the Drake Relays includes athletes from across the country, these differences likely reflect national trends and are possibly explained by forces such as increased pressure for youth sport specialization, declining popularity of track-and-field, and Title IX.Drake University, College of Arts and Sciences, Department of Biology, Biochemistry, Cell and Molecular Biology ; College of Pharmacy and Health Science

    Torsional Sensor Applications in Two-Phase Fluids

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    A solid corrosion-resistant torsional waveguide of diamond cross section has been developed to sense on-line and in real-time the characteristics of the liquid in which it is submerged. The sensor can measure, among other things, the liquid content of a bubbly medium; the density of adjacent pure liquids; the equivalent density of liquid-vapor mixtures or particulate suspensions; a suspension\u27s concentration; and the liquid level. The sensor exploits the phenomenon that the speed of propagation of a torsional stress wave in a submerged waveguide with a noncircular cross section is inversely proportional to the equivalent density of the liquid in which the waveguide is submerged. The sensor may be used to conduct measurements along distances ranging from 20 mm to 20 m and over a wide range of temperatures and pressures, e.g., from the cryogenic temperature of liquid nitrogen, -196°C, up to hot pressurized water at 300°C and 7 MPa. A self-calibrating three-zone sensor and associated electronics have also been developed to compensate for any sensor inaccuracies due to operation over a wide range of temperature. In some of the water experiments at room temperature, unexpected attenuation of the guided torsional waves was observed. This excess attenuation depends in part on the waveguide\u27s surface finish. It appears to be caused by air microbubbles adhering to the waveguide, imposing one of the practical limits on the maximum sensor length in nondegassed or aerated water

    Frequency and Nature of Incidental Extra-Enteric Lesions Found on Magnetic Resonance Enterography (MR-E) in Patients with Inflammatory Bowel Diseases (IBD)

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    The aim of this study was to determine the occurrence of extra-enteric findings in a large cohort of patients undergoing magnetic resonance enterography (MR-E) and to classify the clinical significance of these findings.We retrospectively analyzed 1154 MR-E performed in 1006 patients referred to our radiological department between 1999-2005. The reasons for referral were suspected or proven inflammatory bowel diseases (IBD) (n = 710), further diagnostic work-up for small bowel disease because of non-specific abdominal symptoms (SBD; n = 182) or suspected small bowel malignancies (SBM; n = 114). All extra-enteric findings were reviewed by a radiologist and a gastroenterologist and were classified as having high, moderate, or low significance for further diagnostic or therapeutic procedures.The average age of all patients was 40+/-16 (Mean+/-SD) years (y) (IBD 35+/-13 y; SBD 49+/-16 y; SBM 57+/-15 y). A total of 1113 extra-enteric findings were detected in 600 of 1006 patients (59.6%). Of these findings 180 (16.2%) were judged as having a high, 212 (19.0%) a moderate and 721 (64.8%) a low significance. On a per group basis in patients with IBD 12.0% of the findings were of major clinical significance compared to 13.7% and 33.3% in patients with SBD and SBM, respectively. The most common major findings were abscesses (69.9%) in the IBD group and extraintestinal tumors, metastases or masses in the SBD and SBM groups (41.9% and 74.2%, respectively).MR-E reveals a substantial number of extra-enteric findings, supporting the role of a cross-sectional imaging method for the evaluation of the small bowel

    Cell Specific eQTL Analysis without Sorting Cells

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    The functional consequences of trait associated SNPs are often investigated using expression quantitative trait locus (eQTL) mapping. While trait-associated variants may operate in a cell-type specific manner, eQTL datasets for such cell-types may not always be available. We performed a genome-environment interaction (GxE) meta-analysis on data from 5,683 samples to infer the cell type specificity of whole blood cis-eQTLs. We demonstrate that this method is able to predict neutrophil and lymphocyte specific cis-eQTLs and replicate these predictions in independent cell-type specific datasets. Finally, we show that SNPs associated with Crohn’s disease preferentially affect gene expression within neutrophils, including the archetypal NOD2 locus

    Genetic and clinical determinants of abdominal aortic diameter: genome-wide association studies, exome array data and Mendelian randomization study

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    Progressive dilation of the infrarenal aortic diameter is a consequence of the ageing process and is considered the main determinant of abdominal aortic aneurysm (AAA). We aimed to investigate the genetic and clinical determinants of abdominal aortic diameter (AAD). We conducted a meta-analysis of genome-wide association studies in 10 cohorts (n = 13 542) imputed to the 1000 Genome Project reference panel including 12 815 subjects in the discovery phase and 727 subjects [Partners Biobank cohort 1 (PBIO)] as replication. Maximum anterior–posterior diameter of the infrarenal aorta was used as AAD. We also included exome array data (n = 14 480) from seven epidemiologic studies. Single-variant and gene-based associations were done using SeqMeta package. A Mendelian randomization analysis was applied to investigate the causal effect of a number of clinical risk factors on AAD. In genome-wide association study (GWAS) on AAD, rs74448815 in the intronic region of LDLRAD4 reached genome-wide significance (beta = −0.02, SE = 0.004, P-value = 2.10 × 10(−8)). The association replicated in the PBIO1 cohort (P-value = 8.19 × 10(−4)). In exome-array single-variant analysis (P-value threshold = 9 × 10(−7)), the lowest P-value was found for rs239259 located in SLC22A20 (beta = 0.007, P-value = 1.2 × 10(−5)). In the gene-based analysis (P-value threshold = 1.85 × 10(−6)), PCSK5 showed an association with AAD (P-value = 8.03 × 10(−7)). Furthermore, in Mendelian randomization analyses, we found evidence for genetic association of pulse pressure (beta = −0.003, P-value = 0.02), triglycerides (beta = −0.16, P-value = 0.008) and height (beta = 0.03, P-value < 0.0001), known risk factors for AAA, consistent with a causal association with AAD. Our findings point to new biology as well as highlighting gene regions in mechanisms that have previously been implicated in the genetics of other vascular diseases

    What are the current barriers to effective cancer care coordination? A qualitative study

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    <p>Abstract</p> <p>Background</p> <p>National cancer policies identify the improvement of care coordination as a priority to improve the delivery of health services for people with cancer. Identification of the current barriers to effective cancer care coordination is needed to drive service improvement.</p> <p>Methods</p> <p>A qualitative study was undertaken in which semi-structured individual interviews and focus groups were conducted with those best placed to identify issues; patients who had been treated for a range of cancers and their carers as well as health professionals involved in providing cancer care. Data collection continued until saturation of concepts was reached. A grounded theory influenced approach was used to explore the participants' experiences and views of cancer care coordination.</p> <p>Results</p> <p>Overall, 20 patients, four carers and 29 health professionals participated. Barriers to cancer care coordination related to six aspects of care namely, recognising health professional roles and responsibilities, implementing comprehensive multidisciplinary team meetings, transitioning of care: falling through the cracks, inadequate communication between specialist and primary care, inequitable access to health services and managing scarce resources.</p> <p>Conclusions</p> <p>This study has identified a number of barriers to coordination of cancer care. Development and evaluation of interventions based on these findings is now required.</p
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