V-like formations in flocks of artificial birds

We consider flocks of artificial birds and study the emergence of V-like formations during flight. We introduce a small set of fully distributed positioning rules to guide the birds' movements and demonstrate, by means of simulations, that they tend to lead to stabilization into several of the well-known V-like formations that have been observed in nature. We also provide quantitative indicators that we believe are closely related to achieving V-like formations, and study their behavior over a large set of independent simulations

Spacial and Temporal Variations in 36CI Deposition in the Northern United States

Chlorine-36, a cosmogenic radioisotope, has been developed for use as a tracer in hydrological systems. The deposition of atmospheric 36Cl, although of primary importance to hydrological applications, has not been well studied. To begin to address this problem, 36Cl has been measured in monthly, wet-only, precipitation samples collected from February, 1991, to January, 1993, at the Elms Environmental Education Center in St. Mary's County, Maryland. In addition, bulk deposition samples were collected over a 1 y period at seven sites across the Northern United States and analyzed for 36CI. The mean, wet-only 36Cl/Cl ratio for the 2 y sampling period is 68±19 (x10 -15), and the mean 36 CI concentration is 1.2±0. 1 (x10 6) atoms/L. The 36Cl wet deposition flux data reveal a distinct seasonal deposition pattern, with peaks occurring in March and April. This pattern is attributed to stratospheric/ tropospheric exchange. The mean 36Cl wet deposition flux is 38.2±5 atoms/m2s. Comparison between wet-only and bulk deposition samples indicates that the difference accounts for approximately 25% of the total 36Cl deposition flux at the Elms site. A new model, using 90Sr to predict the 36CI deposition pattern, is developed to predict 36Cl/Cl ratios across the United States. Chlorine-36/Cl ratios in bulk deposition samples collected across the northern United States agree well with the model predictions. A mean global 36Cl production rate of approximately 28 to 38 atoms/m2s is indicated by these samples. A comparison between 36Cl concentrations in the Aquia and Magothy aquifers is southern Maryland and bulk deposition samples collected at the Elms, MD, site indicated that modern precipitation can account for the 36Cl content in the youngest water in these aquifers. Surface water samples from the Susquehanna River basin reveal 36 Cl and stable chloride concentrations an order of magnitude higher than in bulk deposition samples collected at State College, PA. The source of excess 36Cl in the Susquehanna is not known. Possible explanations include 'bomb-pulse' 36Cl and in-situ 36CI production in surface rocks

Matching times of leading and following suggest cooperation through direct reciprocity during V-formation flight in ibis

One conspicuous feature of several larger bird species is their annual migration in V-shaped or echelon formation. When birds are flying in these formations, energy savings can be achieved by using the aerodynamic up-wash produced by the preceding bird. As the leading bird in a formation cannot profit from this up-wash, a social dilemma arises around the question of who is going to fly in front? To investigate how this dilemma is solved, we studied the flight behavior of a flock of juvenile Northern bald ibis (Geronticus eremita) during a human-guided autumn migration. We could show that the amount of time a bird is leading a formation is strongly correlated with the time it can itself profit from flying in the wake of another bird. On the dyadic level, birds match the time they spend in the wake of each other by frequent pairwise switches of the leading position. Taken together, these results suggest that bald ibis cooperate by directly taking turns in leading a formation. On the proximate level, we propose that it is mainly the high number of iterations and the immediacy of reciprocation opportunities that favor direct reciprocation. Finally, we found evidence that the animals' propensity to reciprocate in leading has a substantial influence on the size and cohesion of the flight formations

International systematic review of utility values associated with cardiovascular disease and reflections on selecting evidence for a UK decision-analytic model

Purpose: Evaluating interventions for cardiovascular disease (CVD) requires estimates of its effect on utility. We aimed to (1) systematically review utility estimates for CVDs published since 2013, (2) critically appraise UK-relevant estimates and calculate corresponding baseline utility multipliers. Methods: We searched MEDLINE and Embase (22/04/2021) using CVD and utility terms. We screened results for primary studies reporting utility distributions for people with experience of heart failure, myocardial infarction, peripheral arterial disease, stable angina, stroke, transient ischemic attack or unstable angina. We extracted characteristics from studies included. For UK estimates based on the EuroQoL five dimension (EQ-5D) measure, we assessed risk of bias and applicability to a decision-analytic model, pooled arms/time-points as appropriate, and estimated baseline utility multipliers using predicted utility for age- and sex- matched populations without CVD. We sought utility sources from directly applicable studies with low risk of bias, prioritising plausibility of severity ordering in our base case model and highest population ascertainment in a sensitivity analysis. Results: Most of the 403 studies identified used EQ-5D (n=217) and most assessed OECD populations (n=262), although measures and countries varied widely. UK studies using EQ-5D (n=29) produced very heterogeneous baseline utility multipliers for each type of CVD, precluding meta-analysis and implying different possible severity orderings. We could find sources which provided a plausible ordering of utilities whilst adequately representing health-states. Conclusions: We catalogued international CVD utility estimates and calculated UK-relevant baseline utility multipliers. Modellers should consider unreported sources of heterogeneity, such as population differences, when selecting utility evidence from reviews.Highlights• Published systematic reviews have summarised estimates of utility associated with cardiovascular disease published up to 2013.• We (1) reviewed utility estimates for seven types of cardiovascular disease published since 2013, (2) critically appraised UK-relevant studies and (3) estimated the effect of each cardiovascular disease on baseline utility.• Our review (1) recommends a consistent and reliable set of baseline utility multipliers for seven types of cardiovascular disease and (2) provides systematically identified reference information for researchers seeking utility evidence for their own context.<br/

Development and testing of the Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS) cm and mm wavelength occultation instrument

We present initial results from testing a new remote sensing system called the Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS). ATOMMS is designed as a satellite-to-satellite occultation system for monitoring climate. We are developing the prototype instrument for an aircraft to aircraft occultation demonstration. Here we focus on field testing of the ATOMMS instrument, in particular the remote sensing of water by measuring the attenuation caused by the 22 GHz and 183 GHz water absorption lines. Our measurements of the 183 GHz line spectrum along an 820 m path revealed that the AM 6.2 spectroscopic model provdes a much better match to the observed spectrum than the MPM93 model. These comparisons also indicate that errors in the ATOMMS amplitude measurements are about 0.3%. Pressure sensitivity bodes well for ATOMMS as a climate instrument. Comparisons with a hygrometer revealed consistency at the 0.05 mb level, which is about 1% of the absolute humidity. Initial measurements of absorption by the 22 GHz line made along a 5.4 km path between two mountaintops captured a large increase in water vapor similar to that measured by several nearby hygrometers. A storm passage between the two instruments yielded our first measurements of extinction by rain and cloud droplets. Comparisons of ATOMMS 1.5 mm opacity measurements with measured visible opacity and backscatter from a weather radar revealed features simultaneously evident in all three datasets confirming the ATOMMS measurements. The combined ATOMMS, radar and visible information revealed the evolution of rain and cloud amounts along the signal path during the passage of the storm. The derived average cloud water content reached typical continental cloud amounts. These results demonstrated a significant portion of the information content of ATOMMS and its ability to penetrate through clouds and rain which is critical to its all-weather, climate monitoring capability

Rapid neuroinflammatory changes in human acute intracerebral hemorrhage

Objective Spontaneous intracerebral hemorrhage (ICH) is the commonest form of hemorrhagic stroke and is associated with a poor prognosis. Neurosurgical removal of intracerebral hematoma has limited benefit and no pharmacotherapies are available. In acute ICH, primary tissue damage is followed by secondary pathology, where the cellular and neuroinflammatory changes are poorly understood. Methods We studied histological changes in postmortem tissue from a cohort of spontaneous supra‐tentorial primary ICH cases (n = 27) with survival of 1–12 days, compared to a matched control group (n = 16) examined in corresponding regions. Hematoxylin–eosin and microglial (Iba1) immunolabelled sections were assessed at 0–2, 3–5, and 7–12 days post‐ICH. Results Peri‐hematoma, the observed ICH‐related changes include edema, tissue neutrophils and macrophages from day 1. Ischemic neurons and swollen endothelial cells were common at day 1 and universal after day 5, as were intramural erythrocytes within small vessel walls. Activated microglia were evident at day 1 post‐ICH. There was a significant increase in Iba1 positive area fraction at 0–2 (threefold), 3–5 (fourfold), and 7–12 days post ICH (ninefold) relative to controls. Giant microglia were detected peri‐hematoma from day 5 and consistently 7–12 days post‐ICH. Interpretation Our data indicate that neuroinflammatory processes commence from day 1 post‐ICH with changing microglial size and morphology following ICH and up to day 12. From day 5 some microglia exhibit a novel multiply nucleated morphology, which may be related to changing phagocytic function. Understanding the time course of neuroinflammatory changes, post‐ICH may reveal novel targets for therapy and brain restoration

High efficacy and low toxicity of weekly docetaxel given as first-line treatment for metastatic breast cancer

Background: Docetaxel is one of the most effective antitumor agents currently available for the treatment of metastatic breast cancer (MBC). This phase II multicenter study prospectively analyzed the efficacy and toxicity of docetaxel given on a weekly schedule as first-line treatment of metastatic breast cancer. Patients and Methods: All patients received docetaxel, 35 mg/m(2) weekly for 6 weeks, followed by 2 weeks of rest. Subsequent cycles ( 3 weeks of treatment, 2 weeks of rest) were given until a maximum of 5 cycles or disease progression. Premedication consisted of 8 mg dexamethasone intravenously 30 min prior to the infusion of docetaxel. Results: Fifty-four patients at a median age of 58 years with previously untreated MBC were included in the study. A median of 10 doses ( median cumulative dose 339 mg/m(2)) was administered ( range: 2 - 18). The overall response rate was 48.1% ( 95% CI: 34 - 61%, intent-to-treat). Median survival was 15.8 months and median time to progression was 5.9 months ( intent-to-treat). Hematological toxicity was mild with absence of neutropenia-related complications. Grade 3 neutropenia was observed in 3.7% of patients and grade 3 and 4 anemia was observed in 5.6 and 1.9% of patients, respectively. Conclusion: The weekly administration of docetaxel is highly efficient and safe as first-line treatment for MBC and may serve as an important treatment option specifically in elderly patients and patients with a reduced performance status. Copyright (C) 2005 S. Karger AG, Basel