2,258 research outputs found
Simulating the Software Development Lifecycle: The Waterfall Model
(1) Background: This study employs a simulation-based approach, adapting the
waterfall model, to provides estimates for projects and individual phase
completion times. Additionally, it pin-points potential efficiency issues
stemming from a suboptimal resource level. It further demonstrates how one can
go on to identify a resource level that effectively eliminates bottlenecks and
curtails the idle time of resources. (2) Methods: We implement our software
development lifecycle using SimPy, a discrete-event simulation framework
written in Python. Our model is executed on 100 projects of varying sizes over
three stages. The first, pre-optimization, provides insight based on the
initial set of resources. This is followed by the optimization stage, which
serves to identify the optimal number of resources to eliminate bottlenecks and
minimize idle time. The third stage, post-optimization, evaluates the resource
optimized model. (3) Results: The analysis of the simulation-generated data
reveals the presence of resource bottlenecks during the pre-optimization stage,
particularly in the implementation phase. These dissipate after optimization.
(4) Conclusions: The findings emphasize the advantage of using simulation as a
safe and effective way to experiment and plan for software development
projects. Such simulations also allow those man-aging software development
projects to make accurate, evidence-based projections as to phase and project
completion times and identify optimal resource levels and their interplay. In
particular, understanding the tradeoffs between experiencing delayed completion
times and procuring additional resources to alleviate any bottlenecks
Defining the local nerve blocks for feline distal thoracic limb surgery: a cadaveric study
Though controversial, onychectomy remains a commonly performed distal thoracic limb surgical procedure in cats. Peripheral nerve block techniques have been proposed in cats undergoing onychectomy but evidence of efficacy is lacking. Preliminary tests of the described technique using cadavers resulted in incomplete staining of nerves. The aim of this study was to develop nerve block methods based on cadaveric dissections and test these methods with cadaveric dye injections
Analysis of alternative signaling pathways of endoderm induction of human embryonic stem cells identifies context specific differences
Background: Lineage specific differentiation of human embryonic stem cells (hESCs) is largely mediated by specific growth factors and extracellular matrix molecules. Growth factors initiate a cascade of signals which control gene transcription and cell fate specification. There is a lot of interest in inducing hESCs to an endoderm fate which serves as a pathway towards more functional cell types like the pancreatic cells. Research over the past decade has established several robust pathways for deriving endoderm from hESCs, with the capability of further maturation. However, in our experience, the functional maturity of these endoderm derivatives, specifically to pancreatic lineage, largely depends on specific pathway of endoderm induction. Hence it will be of interest to understand the underlying mechanism mediating such induction and how it is translated to further maturation. In this work we analyze the regulatory interactions mediating different pathways of endoderm induction by identifying co-regulated transcription factors.Results: hESCs were induced towards endoderm using activin A and 4 different growth factors (FGF2 (F), BMP4 (B), PI3KI (P), and WNT3A (W)) and their combinations thereof, resulting in 15 total experimental conditions. At the end of differentiation each condition was analyzed by qRT-PCR for 12 relevant endoderm related transcription factors (TFs). As a first approach, we used hierarchical clustering to identify which growth factor combinations favor up-regulation of different genes. In the next step we identified sets of co-regulated transcription factors using a biclustering algorithm. The high variability of experimental data was addressed by integrating the biclustering formulation with bootstrap re-sampling to identify robust networks of co-regulated transcription factors. Our results show that the transition from early to late endoderm is favored by FGF2 as well as WNT3A treatments under high activin. However, induction of late endoderm markers is relatively favored by WNT3A under high activin.Conclusions: Use of FGF2, WNT3A or PI3K inhibition with high activin A may serve well in definitive endoderm induction followed by WNT3A specific signaling to direct the definitive endoderm into late endodermal lineages. Other combinations, though still feasible for endoderm induction, appear less promising for pancreatic endoderm specification in our experiments. © 2012 Mathew et al.; licensee BioMed Central Ltd
Numerical studies towards practical large-eddy simulation
Large-eddy simulation developments and validations are presented for an
improved simulation of turbulent internal flows. Numerical methods are proposed
according to two competing criteria: numerical qualities (precision and
spectral characteristics), and adaptability to complex configurations. First,
methods are tested on academic test-cases, in order to abridge with fundamental
studies. Consistent results are obtained using adaptable finite volume method,
with higher order advection fluxes, implicit grid filtering and "low-cost"
shear-improved Smagorinsky model. This analysis particularly focuses on mean
flow, fluctuations, two-point correlations and spectra. Moreover, it is shown
that exponential averaging is a promising tool for LES implementation in
complex geometry with deterministic unsteadiness. Finally, adaptability of the
method is demonstrated by application to a configuration representative of
blade-tip clearance flow in a turbomachine
Effect of electron irradiation on the properties of CdTe/CdS solar cells
Abstract Polycrystalline CdTe/CdS solar cells are used in space, as well as terrestrial, applications. The results of the studies on the effect of 8 MeV electron irradiation on p-CdTe/n-CdS thin film solar cells prepared by radio frequency (RF) sputtering are presented in this article. Solar cell parameters like short circuit current (I sc ), open circuit voltage (V oc ), fill factor (FF), conversion efficiency (Z), saturation current (I s ) and ideality factor (n) have been considered. CdTe thin film solar cells exhibit good stability against electron irradiation up to 100 kGy.
Spectral distribution of photoelectric quantum yield of thin-film Au-CdTe diode structure
A study of the Au/CdTe Schottky diodes fabricated by vacuum evaporation of
a semitransparent Au layer over an electrodeposited CdTe thin film is reported. The
theoretical model of the photocurrent spectra for an Au/CdTe Schottky diode based on
the continuity equation and incorporating the surface recombination losses does not
explain the measured spectra in the entire range of wavelengths, particularly the abovementioned
decay in the short-wavelength region. The satisfactory description of the
measured spectra is achieved by proposing a model, in which the surface recombination
along with the Schottky effect resulted in the presence of a dead layer in the space-charge
region is taken into account. By varying the parameters such as uncompensated carrier
concentration and carrier lifetime, the above model can explain the actual photoresponse
spectra
Quantum nondemolition measurement of mechanical motion quanta
The fields of opto- and electromechanics have facilitated numerous advances
in the areas of precision measurement and sensing, ultimately driving the
studies of mechanical systems into the quantum regime. To date, however, the
quantization of the mechanical motion and the associated quantum jumps between
phonon states remains elusive. For optomechanical systems, the coupling to the
environment was shown to preclude the detection of the mechanical mode
occupation, unless strong single photon optomechanical coupling is achieved.
Here, we propose and analyse an electromechanical setup, which allows to
overcome this limitation and resolve the energy levels of a mechanical
oscillator. We find that the heating of the membrane, caused by the interaction
with the environment and unwanted couplings, can be suppressed for carefully
designed electromechanical systems. The results suggest that phonon number
measurement is within reach for modern electromechanical setups.Comment: 8 pages, 5 figures plus 24 pages, 11 figures supplemental materia
Characterising risk of non-steroidal-anti-inflammatory drug related acute kidney injury: a retrospective cohort study
BACKGROUND: Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly prescribed for pain and inflammation. NSAID complications include acute kidney injury (AKI), causing burden to patients and health services through increased morbidity, mortality, and hospital admissions. AIM: To measure the extent of NSAID prescribing in an adult population, the degree to which patients with potential higher risk of AKI were exposed to NSAIDs, and to quantify their risk of AKI. DESIGN & SETTING: Retrospective 2-year closed-cohort study. METHOD: A retrospective cohort of adults was identified from a pseudonymised electronic primary care database in Hampshire, UK. The cohort had clinical information, prescribing data, and complete GP- and hospital-ordered biochemistry data. NSAID exposure (minimum one prescription in a 2-month period) was categorised as never, intermittent, and continuous, and first AKI using the national AKI e-alert algorithm. Descriptive statistics and logistic regression were used to explore NSAID prescribing patterns and AKI risk. RESULTS: The baseline population was 702 265. NSAID prescription fell from 19 364 (2.8%) to 16 251 (2.4%) over 2 years. NSAID prescribing was positively associated with older age, female sex, greater socioeconomic deprivation, and certain comorbidities (diabetes, hypertension, osteoarthritis, and rheumatoid arthritis) and negatively with cardiovascular disease (CVD) and heart failure. Among those prescribed NSAIDs, AKI was associated with older age, greater deprivation, chronic kidney disease (CKD), CVD, heart failure, diabetes, and hypertension. CONCLUSION: Despite generally good prescribing practice, NSAID prescribing was identified in some people at higher risk of AKI (for example, patients with CKD and older) for whom medication review and NSAID deprescribing should be considered
Identifying individuals with persistently normal safety monitoring blood tests whilst taking methotrexate for rheumatoid arthritis or azathioprine for inflammatory bowel disease:a retrospective cohort study
Large-scale discovery of male reproductive tract-specific genes through analysis of RNA-seq datasets
Robertson, M.J., Kent, K., Tharp, N. et al. Large-scale discovery of male reproductive tract-specific genes through analysis of RNA-seq datasets. BMC Biol 18, 103 (2020). https://doi.org/10.1186/s12915-020-00826-
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