695 research outputs found
Diffusion with random distribution of static traps
The random walk problem is studied in two and three dimensions in the
presence of a random distribution of static traps. An efficient Monte Carlo
method, based on a mapping onto a polymer model, is used to measure the
survival probability P(c,t) as a function of the trap concentration c and the
time t. Theoretical arguments are presented, based on earlier work of Donsker
and Varadhan and of Rosenstock, why in two dimensions one expects a data
collapse if -ln[P(c,t)]/ln(t) is plotted as a function of (lambda
t)^{1/2}/ln(t) (with lambda=-ln(1-c)), whereas in three dimensions one expects
a data collapse if -t^{-1/3}ln[P(c,t)] is plotted as a function of
t^{2/3}lambda. These arguments are supported by the Monte Carlo results. Both
data collapses show a clear crossover from the early-time Rosenstock behavior
to Donsker-Varadhan behavior at long times.Comment: 4 pages, 6 figure
N, NH, and NH2 radical densities in a remote Ar-NH3-SiH4 plasma and their role in silicon nitride deposition
The densities of N, NH, and NH2 radicals in a remote Ar-NH3-SiH4 plasma used for high-rate silicon nitride deposition were investigated for different gas mixts. and plasma settings using cavity ringdown absorption spectroscopy and threshold ionization mass spectrometry. For typical deposition conditions, the N, NH, and NH2 radical densities are on the order of 1012 cm-3 and the trends with NH3 flow, SiH4 flow, and plasma source current are reported. We present a feasible reaction pathway for the prodn. and loss of the NHx radicals that is consistent with the exptl. results. Furthermore, mass spectrometry revealed that the consumption of NH3 was typically 40%, while it was over 80% for SiH4. On the basis of the measured N densities we deduced the recombination and sticking coeff. for N radicals on a silicon nitride film. Using this sticking coeff. and reported surface reaction probabilities of NH and NH2 radicals, we conclude that N and NH2 radicals are mainly responsible for the N incorporation in the silicon nitride film, while Si atoms are most likely brought to the surface in the form of SiHx radicals. [on SciFinder (R)
Order statistics of the trapping problem
When a large number N of independent diffusing particles are placed upon a
site of a d-dimensional Euclidean lattice randomly occupied by a concentration
c of traps, what is the m-th moment of the time t_{j,N} elapsed
until the first j are trapped? An exact answer is given in terms of the
probability Phi_M(t) that no particle of an initial set of M=N, N-1,..., N-j
particles is trapped by time t. The Rosenstock approximation is used to
evaluate Phi_M(t), and it is found that for a large range of trap
concentracions the m-th moment of t_{j,N} goes as x^{-m} and its variance as
x^{-2}, x being ln^{2/d} (1-c) ln N. A rigorous asymptotic expression (dominant
and two corrective terms) is given for for the one-dimensional
lattice.Comment: 11 pages, 7 figures, to be published in Phys. Rev.
Efficacy and Safety of Technosphere Inhaled Insulin Compared With Technosphere Powder Placebo in Insulin-Naive Type 2 Diabetes Suboptimally Controlled With Oral Agents
OBJECTIVE—This double-blind, placebo-controlled, randomized, multicenter, parallel-group study compared the efficacy, safety, and tolerability of Technosphere insulin with Technosphere powder as placebo in insulin-naive type 2 diabetic patients whose diabetes was suboptimally controlled with oral antidiabetic agents
Two-Year Pulmonary Safety and Efficacy of Inhaled Human Insulin (Exubera) in Adult Patients With Type 2 Diabetes
OBJECTIVE—The purpose of this study was to evaluate the 2-year pulmonary safety of inhaled human insulin (Exubera [EXU]) in 635 nonsmoking adults with type 2 diabetes
Comparative effectiveness of dipeptidyl peptidase-4 (DPP-4) inhibitors and human glucagon-like peptide-1 (GLP-1) analogue as add-on therapies to sulphonylurea among diabetes patients in the Asia-Pacific region: a systematic review
The prevalence of diabetes mellitus is rising globally, and it induces a substantial public health burden to the healthcare systems. Its optimal control is one of the most significant challenges faced by physicians and policy-makers. Whereas some of the established oral hypoglycaemic drug classes like biguanide, sulphonylureas, thiazolidinediones have been extensively used, the newer agents like dipeptidyl peptidase-4 (DPP-4) inhibitors and the human glucagon-like peptide-1 (GLP-1) analogues have recently emerged as suitable options due to their similar efficacy and favorable side effect profiles. These agents are widely recognized alternatives to the traditional oral hypoglycaemic agents or insulin, especially in conditions where they are contraindicated or unacceptable to patients. Many studies which evaluated their clinical effects, either alone or as add-on agents, were conducted in Western countries. There exist few reviews on their effectiveness in the Asia-Pacific region. The purpose of this systematic review is to address the comparative effectiveness of these new classes of medications as add-on therapies to sulphonylurea drugs among diabetic patients in the Asia-Pacific countries. We conducted a thorough literature search of the MEDLINE and EMBASE from the inception of these databases to August 2013, supplemented by an additional manual search using reference lists from research studies, meta-analyses and review articles as retrieved by the electronic databases. A total of nine randomized controlled trials were identified and described in this article. It was found that DPP-4 inhibitors and GLP-1 analogues were in general effective as add-on therapies to existing sulphonylurea therapies, achieving HbA1c reductions by a magnitude of 0.59–0.90% and 0.77–1.62%, respectively. Few adverse events including hypoglycaemic attacks were reported. Therefore, these two new drug classes represent novel therapies with great potential to be major therapeutic options. Future larger-scale research should be conducted among other Asia-Pacific region to evaluate their efficacy in other ethnic groups
DURAbility of Basal Versus Lispro Mix 75/25 Insulin Efficacy (DURABLE) Trial 24-Week Results: Safety and efficacy of insulin lispro mix 75/25 versus insulin glargine added to oral antihyperglycemic drugs in patients with type 2 diabetes
OBJECTIVE - To compare the ability of two starter insulin regimens to achieve glycemic control in a large, ethnically diverse population with type 2 diabetes. RESEARCH DESIGN AND METHODS - During the initiation phase of the DURABLE trial, patients were randomized to a twice-daily lispro mix 75/25 (LM75/25; 75% lispro protamine suspension, 25% lispro) (n = 1,045) or daily glargine (GL) (n = 1,046) with continuation of prestudy oral antihyperglycemic drugs. RESULTS - Baseline A1C was similar (LM75/25: 9.1 +/- 1.3%; GL: 9.0 +/- 1.2%; P = 0.414). At 24 weeks, LM75/25 patients had tower A1C than GL patients (7.2 +/- 1.1. vs. 7.3 +/- 1.1%, P = 0.005), greater A1C reduction (-1.8 +/- 1.3 vs. -1.7 +/- 1.3%, P = 0.005), and higher percentage reaching A1C target CONCLUSIONS - Compared With GL, LM75/25 resulted in slightly lower A1C at 24 weeks and a moderately higher percentage reaching A1C targe
The scientific basis of climate-smart agriculture: A systematic review protocol
Background: ‘Climate-smart agriculture’ (CSA)—agriculture and food systems that
sustainably increase food production, improve resilience (or adaptive capacity) of farming
systems, and mitigate climate change when possible—has quickly been integrated into the
global development agenda. However, the empirical evidence base for CSA has not been
assembled, complicating the transition from CSA concept to concrete actions, and
contributing to ideological disagreement among development practitioners. Thus, there is an
urgent need to evaluate current knowledge on the effectiveness of CSA to achieve its intended
benefits and inform discourse on food, agriculture, and climate change. This systematic
review intends to establish the scientific evidence base of CSA practices to inform the next
steps in development of agricultural programming and policy. We will evaluate the impact of
73 promising farm-level management practices across five categories (agronomy,
agroforestry, livestock, postharvest management, and energy systems) to assess their
contributions to the three CSA pillars: (1) agronomic and economic productivity, (2)
resilience and adaptive capacity, and (3) climate change mitigation in the developing world.
The resulting data will be compiled into a searchable Web-based database and analytical
engine that can be used to assess the relative effectiveness and strength of evidence for CSA,
as well as identify best-fit practices for specific farming and development contexts. This
represents the largest meta-analysis of agricultural practices to date.
Methods/Design: This protocol sets out the approach for investigating the question: How do
farm-level CSA management practices and technologies affect food production and/or
farmers’ incomes, resilience/adaptive capacity, and climate change mitigation in farming
systems of developing countries? The objective of this ongoing systematic review is to
provide a first appraisal of the evidence for CSA practices in order to inform subsequent
programming. The review is based on data found in English-language peer-reviewed journals
with searches using terms relevant to CSA practices and CSA outcomes. Searches were
conducted via Web of Science (WoS) and Scopus. Articles located were screened first by
abstract and then full text according to predefined eligibility criteria for inclusion in the
review. Data capturing the context of the study (e.g., geographic location, environmental
context), management practices, and impacts (e.g., indicators of CSA outcomes) will be
compiled from those studies that meet the predetermined criteria. Statistical relationships
between practices and impacts will be evaluated via meta-analytical approaches including
response ratios and effect sizes. Mechanisms to identify bias and maintain consistency
continue to be applied throughout the review process. These analyses will be complemented
with an analysis of determinants of/barriers to adoption of promising CSA practices covered
in the meta-analysis. Results of the review will be incorporated into a publicly available Web-based
database. Data will be publicly available under Creative Commons License in 2016
Benefits and Harms of Sodium-Glucose Co-Transporter 2 Inhibitors in Patients with Type 2 Diabetes: A Systematic Review and Meta-Analysis
Sodium-glucose co-transporter 2 inhibitors (SGLT2-i) are a novel drug class for the treatment of diabetes. We aimed at describing the maximal benefits and risks associated with SGLT2-i for patients with type 2 diabetes.Systematic review and meta-analysis.We included double-blinded, randomised controlled trials (RCTs) evaluating SGLT2-i administered in the highest approved therapeutic doses (canagliflozin 300 mg/day, dapagliflozin 10 mg/day, and empagliflozin 25 mg/day) for ≥12 weeks. Comparison groups could receive placebo or oral antidiabetic drugs (OAD) including metformin, sulphonylureas (SU), or dipeptidyl peptidase 4 inhibitors (DPP-4-i). Trials were identified through electronic databases and extensive manual searches. Primary outcomes were glycated haemoglobin A1c (HbA1c) levels, serious adverse events, death, severe hypoglycaemia, ketoacidosis and CVD. Secondary outcomes were fasting plasma glucose, body weight, blood pressure, heart rate, lipids, liver function tests, creatinine and adverse events including infections. The quality of the evidence was assessed using GRADE.Meta-analysis of 34 RCTs with 9,154 patients showed that SGLT2-i reduced HbA1c compared with placebo (mean difference -0.69%, 95% confidence interval -0.75 to -0.62%). We downgraded the evidence to 'low quality' due to variability and evidence of publication bias (P = 0.015). Canagliflozin was associated with the largest reduction in HbA1c (-0.85%, -0.99% to -0.71%). There were no differences between SGLT2-i and placebo for serious adverse events. SGLT2-i increased the risk of urinary and genital tract infections and increased serum creatinine, and exerted beneficial effects on bodyweight, blood pressure, lipids and alanine aminotransferase (moderate to low quality evidence). Analysis of 12 RCTs found a beneficial effect of SGLT2-i on HbA1c compared with OAD (-0.20%, -0.28 to -0.13%; moderate quality evidence).This review includes a large number of patients with type 2 diabetes and found that SGLT2-i reduces HbA1c with a notable increased risk in non-serious adverse events. The analyses may overestimate the intervention benefit due bias
Associations of Hyperglycemia and Insulin Usage With the Risk of Cancer in Type 2 Diabetes: The Hong Kong Diabetes Registry
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