Constant Queue Route on a Mesh

Packet routing is an important problem in parallel computation since a single step of inter-processor communication can be thought of as a packet routing task. In this paper we present an optimal algorithm for packet routing on a mesh-connected computer. Two important criteria for judging a routing algorithm will be 1) its run time, i.e., the number of parallel steps it takes for the last packet to reach its destination, and 2) its queue size, i.e., the maximum number of packets that any node will have to store at any time during routing. We present a 2n - 2 step routing algorithm for an n x n mesh that requires a queue size of only 58. The previous best known result is a routing algorithm with the same time bound but with a queue size of 672. The time bound of 2n - 2 is optimal. A queue size of 672 is rather large for practical use. We believe that the queue size of our algorithm is practical. The improvement in the queue size is possible due to (from among other things) a new 3s + o(s) sorting algorithm for an s x s mesh

Sex and race and/or ethnicity differences in patients undergoing radiofrequency ablation for Barrett\u27s esophagus: results from the U.S. RFA Registry.

BACKGROUND: Little is known about differences in Barrett\u27s esophagus (BE) characteristics by sex and race and/or ethnicity or these differences in response to radiofrequency ablation (RFA). OBJECTIVE: We compared disease-specific characteristics, treatment efficacy, and safety outcomes by sex and race and/or ethnicity in patients treated with RFA for BE. DESIGN: The U.S. RFA patient registry is a multicenter collaboration reporting processes and outcomes of care for patients treated with RFA for BE. PATIENTS: Patients enrolled with BE. INTERVENTIONS: RFA. MAIN OUTCOME MEASUREMENTS: We assessed safety (stricture, bleeding, perforation, hospitalization), efficacy (complete eradication of intestinal metaplasia [CEIM]), complete eradication of dysplasia, and number of treatments to CEIM by sex and race and/or ethnicity. RESULTS: Among 5521 patients (4052 men; 5126 white, 137 Hispanic, 82 African American, 40 Asian, 136 heritage not identified), women were younger (60.0 vs 62.1 years) and had shorter BE segments (3.2 vs 4.4 cm) and less dysplasia (37% vs 57%) than did men. Women were almost twice as likely to stricture (odds ratio 1.7; 95% confidence interval, 1.2-2.3). Although white patients were predominantly male, about half of African Americans and Asians with BE were female. African Americans and Asians had less dysplasia than white patients. Asians and African Americans had more strictures than did white patients. There were no sex or race differences in efficacy. LIMITATIONS: Observational study with non-mandated paradigms, no central laboratory for reinterpretation of pathology. CONCLUSION: In the U.S. RFA patient registry, women had shorter BE segments and less-aggressive histology. The usual tendency toward BE in men was absent in African Americans and Asians. Posttreatment stricture was more common among women and Asians. RFA efficacy did not differ by sex or race

How spiking neurons give rise to a temporal-feature map

A temporal-feature map is a topographic neuronal representation of temporal attributes of phenomena or objects that occur in the outside world. We explain the evolution of such maps by means of a spike-based Hebbian learning rule in conjunction with a presynaptically unspecific contribution in that, if a synapse changes, then all other synapses connected to the same axon change by a small fraction as well. The learning equation is solved for the case of an array of Poisson neurons. We discuss the evolution of a temporal-feature map and the synchronization of the single cells’ synaptic structures, in dependence upon the strength of presynaptic unspecific learning. We also give an upper bound for the magnitude of the presynaptic interaction by estimating its impact on the noise level of synaptic growth. Finally, we compare the results with those obtained from a learning equation for nonlinear neurons and show that synaptic structure formation may profit from the nonlinearity

Climate change-induced increases in precipitation are reducing the potential for solar ultraviolet radiation to inactivate pathogens in surface waters

Climate change is accelerating the release of dissolved organic matter (DOM) to inland and coastal waters through increases in precipitation, thawing of permafrost, and changes in vegetation. Our modeling approach suggests that the selective absorption of ultraviolet radiation (UV) by DOM decreases the valuable ecosystem service wherein sunlight inactivates waterborne pathogens. Here we highlight the sensitivity of waterborne pathogens of humans and wildlife to solar UV, and use the DNA action spectrum to model how differences in water transparency and incident sunlight alter the ability of UV to inactivate waterborne pathogens. A case study demonstrates how heavy precipitation events can reduce the solar inactivation potential in Lake Michigan, which provides drinking water to over 10 million people. These data suggest that widespread increases in DOM and consequent browning of surface waters reduce the potential for solar UV inactivation of pathogens, and increase exposure to infectious diseases in humans and wildlife.Tis work was supported in part by NSF DEB-1360066 to C.E.W. and S.G.S. We thank M. Molina, S. Corsi, and C. Fitzgerald for their assistance with analyzing the Manitowoc, WI sampl

Micro-finance, women’s empowerment and fertility decline in Bangladesh: How important was women’s agency?

As Nobel Prize winner Amartya Sen has argued “[Bangladesh’s development achievements have] important lessons for other countries across the globe, [in particular a focus on] reducing gender inequality”. A major avenue through which this emphasis has been manifest lies, according to this narrative, in enhancements to women’s agency for instrumental and intrinsic reasons particularly through innovations in family planning and microfinance. The “Bangladesh paradox” of improved wellbeing despite low economic growth over the last four decades is claimed as a paradigmatic case of the spread of both modern family planning programmes and microfinance leading to women’s empowerment and fertility reduction. In this paper we show that the links between microfinance, empowerment and fertility reduction, are fraught with problems, and far from robust; hence the claimed causal links between microfinance and family planning via women’s empowerment needs to be further reconsidered

Durability and Predictors of Successful Radiofrequency Ablation for Barrett’s Esophagus

Following radiofrequency ablation (RFA), patients may experience recurrence of Barrett’s esophagus (BE) after complete eradication of intestinal metaplasia (CEIM). Rates and predictors of recurrence after successful eradication are poorly described

Incidence of Esophageal Adenocarcinoma and Causes of Mortality After Radiofrequency Ablation of Barrett’s Esophagus

Radiofrequency ablation (RFA) is commonly used to treat Barrett's esophagus (BE). We assessed the incidence of esophageal adenocarcinoma (EAC) after RFA, predictors of EAC, and EAC-specific and all-cause mortality rates

Durability of Radiofrequency Ablation in Barrett's Esophagus With Dysplasia

Radiofrequency ablation (RFA) can eradicate dysplasia and intestinal metaplasia in patients with dysplastic Barrett’s esophagus (BE), and reduce rates of esophageal adenocarcinoma. We assessed long-term rates of eradication, durability of neosquamous epithelium, disease progression, and safety of RFA in patients with dysplastic BE