Langevin dynamics encapsulate the microscopic and emergent macroscopic properties of midge swarms

In contrast with bird flocks, fish schools and animal herds, midge swarms maintain cohesion but do not process global order. High-speed imaging techniques are now revealing that these swarms have surprisingly properties. Here I show that simple models found on the Langevin equation are consistent with this wealth of recent observations. The models predict correctly that large accelerations, exceeding 10 g, will be common and they predict correctly the co-existence of core condensed phases surrounded by dilute vapour phases. The models also provide new insights into the influence of environmental conditions on swarm dynamics. They predict that correlations between midges increase the strength of the effective force binding the swarm together. This may explain why such correlations are absent in laboratory swarms but present in natural swarms which contend with the wind and other disturbances. Finally, the models predict that swarms have fluid-like macroscopic mechanical properties and will slosh rather than slide back-and-forth after being abruptly displaced. This prediction offers a promising avenue for future experimentation that goes beyond current quasi-static testing which has revealed solid-like responses

A review of tertiary BIM education for advanced engineering communication with visualization

SPECT with Tc-99m-labeled agents is better able to detect viability after nitrate administration. Nitrates induce vasoclilation and may increase blood flow to severely hypoperfused but viable myocardium, thereby enhancing tracer delivery and improving the detection of viability. Quantitative data on the changes in blood flow are lacking in SPECT but can be provided by PET. The aim of the present study was to use PET to evaluate whether nitrate administration increases blood flow to chronically dysfunctional but viable myocardium. Methods: N-13-Ammonia PET was used to quantitatively assess blood flow, and F-18-FDG PET was used as the gold standard to detect viable myocardium. Twenty-five patients with chronic ischemic left ventricular dysfunction underwent N-13-ammonia PET at rest and after nitrate administration. Results: A significant increase in nitrate-enhanced blood flow was observed in viable segments (from 0.55 +/- 0.15 to 0.68 +/- 0.24 mL/min/g, P <0.05). No statistically significant change in blood flow was observed in nonviable segments (0.60 +/- 0.20 vs. 0.55 +/- 0.18 mL/min/g). A ratio of at least 1.1 for nitrate-enhanced flow to resting flow allowed optimal detection of viable myocardium, yielding a sensitivity of 82% with a specificity of 100%. Conclusion: N-13-Ammonia PET showed a significant increase in nitrate-enhanced blood flow in viable myocardium, whereas blood flow remained unchanged after nitrate administration in nonviable myocardium. Nitrate use during myocardial perfusion imaging will lead to improved assessment of myocardial viability

Current trends in the surgical management of Dupuytren’s disease in Europe: an analysis of patient charts

Introduction: Dupuytren's disease (DD) causes progressive digital flexion contracture and is more common in men of European descent. Methods: Orthopaedic and plastic surgeons in 12 European countries (the Czech Republic, Denmark, Finland, France, Germany, Hungary, Italy, The Netherlands, Poland, Spain, Sweden and the UK) with >3 and <30 years experience reviewed the medical charts of five consecutive patients they had treated surgically for DD in 2008. Descriptive statistics are reported. Results: In total, 3,357 patient charts were reviewed. Mean (standard deviation) patient age was 61.9 (10.2) years; 81% were men. At the time of the procedure, 11% of patients were at Tubiana stage Ia (0-20° total flexion); 30%, stage Ib (21-45°); 34%, stage II (46-90°); 17%, stage III (91-135°); and 5%, stage IV (&135°). Percutaneous needle fasciotomy was performed in 10%, fasciotomy in 13%, fasciectomy in 69% and dermofasciectomy (DF) in 6% of patients. After surgery, fingers improved a mean of 1.9 Tubiana stages, and 54% of patients had no nodules or contracture. The rate of reported complications during the procedure was 4% overall (11% in patients undergoing DF). The most common postoperative complications reported were haematoma (8%), wound healing complications (6%) and pain (6%). No postoperative complications were reported in 77% of patients. Conclusions: In this European study of more than 3,000 patients with DD, most patients were diagnosed at Tubiana stage I or II, the majority received fasciectomy and more than half had no nodules or contracture remaining after surgery

Topological Lattice Actions

We consider lattice field theories with topological actions, which are invariant against small deformations of the fields. Some of these actions have infinite barriers separating different topological sectors. Topological actions do not have the correct classical continuum limit and they cannot be treated using perturbation theory, but they still yield the correct quantum continuum limit. To show this, we present analytic studies of the 1-d O(2) and O(3) model, as well as Monte Carlo simulations of the 2-d O(3) model using topological lattice actions. Some topological actions obey and others violate a lattice Schwarz inequality between the action and the topological charge Q. Irrespective of this, in the 2-d O(3) model the topological susceptibility \chi_t = \l/V is logarithmically divergent in the continuum limit. Still, at non-zero distance the correlator of the topological charge density has a finite continuum limit which is consistent with analytic predictions. Our study shows explicitly that some classically important features of an action are irrelevant for reaching the correct quantum continuum limit.Comment: 38 pages, 12 figure

Activation of mGluR5 Induces Rapid and Long-Lasting Protein Kinase D Phosphorylation in Hippocampal Neurons

Metabotropic glutamate receptors (mGluRs), including mGluR5, play a central role in regulating the strength and plasticity of synaptic connections in the brain. However, the signaling pathways that connect mGluRs to their downstream effectors are not yet fully understood. Here, we report that stimulation of mGluR5 in hippocampal cultures and slices results in phosphorylation of protein kinase D (PKD) at the autophosphorylation site Ser-916. This phosphorylation event occurs within 30 s of stimulation, persists for at least 24 h, and is dependent on activation of phospholipase C and protein kinase C. Our data suggest that activation of PKD may represent a novel signaling pathway linking mGluR5 to its downstream targets. These findings have important implications for the study of the molecular mechanisms underlying mGluR-dependent synaptic plasticity.Howard Hughes Medical InstituteFRAXA Research FoundationNational Institute of Mental Health (U.S.)Eunice Kennedy Shriver National Institute of Child Health and Human Development (U.S.

The impact of frozen sections on final surgical margins in squamous cell carcinoma of the oral cavity and lips: a retrospective analysis over an 11 years period

Taking intraoperative frozen sections (FS) is a widely used procedure in oncologic surgery. However so far no evidence of an association of FS analysis and premalignant changes in the surgical margin exists. Therefore, the aim of this study was to evaluate the impact of FS on different categories of the final margins of squamous cell carcinoma (SCC) of the oral cavity and lips

Search for New Physics in e mu X Data at D0 Using Sleuth: A Quasi-Model-Independent Search Strategy for New Physics

We present a quasi-model-independent search for the physics responsible for electroweak symmetry breaking. We define final states to be studied, and construct a rule that identifies a set of relevant variables for any particular final state. A new algorithm ("Sleuth") searches for regions of excess in those variables and quantifies the significance of any detected excess. After demonstrating the sensitivity of the method, we apply it to the semi-inclusive channel e mu X collected in 108 pb^-1 of ppbar collisions at sqrt(s) = 1.8 TeV at the D0 experiment during 1992-1996 at the Fermilab Tevatron. We find no evidence of new high p_T physics in this sample.Comment: 23 pages, 12 figures. Submitted to Physical Review