Fast Computation of Smith Forms of Sparse Matrices Over Local Rings

We present algorithms to compute the Smith Normal Form of matrices over two families of local rings. The algorithms use the \emph{black-box} model which is suitable for sparse and structured matrices. The algorithms depend on a number of tools, such as matrix rank computation over finite fields, for which the best-known time- and memory-efficient algorithms are probabilistic. For an \nxn matrix $A$ over the ring \Fzfe, where $f^e$ is a power of an irreducible polynomial f \in \Fz of degree $d$, our algorithm requires \bigO(\eta de^2n) operations in \F, where our black-box is assumed to require \bigO(\eta) operations in \F to compute a matrix-vector product by a vector over \Fzfe (and $\eta$ is assumed greater than \Pden). The algorithm only requires additional storage for \bigO(\Pden) elements of \F. In particular, if \eta=\softO(\Pden), then our algorithm requires only \softO(n^2d^2e^3) operations in \F, which is an improvement on known dense methods for small $d$ and $e$. For the ring \ZZ/p^e\ZZ, where $p$ is a prime, we give an algorithm which is time- and memory-efficient when the number of nontrivial invariant factors is small. We describe a method for dimension reduction while preserving the invariant factors. The time complexity is essentially linear in $\mu n r e \log p,$ where $\mu$ is the number of operations in \ZZ/p\ZZ to evaluate the black-box (assumed greater than $n$) and $r$ is the total number of non-zero invariant factors. To avoid the practical cost of conditioning, we give a Monte Carlo certificate, which at low cost, provides either a high probability of success or a proof of failure. The quest for a time- and memory-efficient solution without restrictions on the number of nontrivial invariant factors remains open. We offer a conjecture which may contribute toward that end.Comment: Preliminary version to appear at ISSAC 201

Social information rapidly prioritizes overt but not covert attention in a joint spatial cueing task

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record Coordinating actions with others is crucial for our survival. Our ability to see what others are seeing and to align our visual attention with them facilitates these joint actions. In the present research, we set out to increase our understanding of such joint attention by investigating the extent to which social information would be able to prioritize overt (when moving the eyes to attend) and covert (when shifting attention without eye movements) attention in a joint spatial cueing task. Participants saw a cue and detected a target at the same or a different location alongside an unseen partner of either higher or lower social rank. In a novel twist, participants were led to believe that the cue was connected to the gaze location of their partner. In Experiment 1, where participants were told to not move their eyes (covert attention), the partner's social rank did not change how quickly participants detected targets. But in Experiment 2, where participants were free to move their eyes naturally (overt attention), inhibition of return effects (slower responses to cued than uncued targets) were modulated by their partner's social rank. These social top-down effects occurred already at a short SOA of 150 ms. Our findings suggest that overt attention might provide a key tool for joint action, as it is penetrable for social information at the early stages of information processing.SAGE Junior Research Fellowship

Efficacy of a self-help manual in increasing resilience in carers of adults with depression in Thailand

Caring for a person with a mental illness can have adverse effects on caregivers; however, little is known about how best to help such caregivers. The aim of the present study was to examine the efficacy of a cognitive behaviour therapy-guided self-help manual in increasing resilience in caregivers of individuals with depression, in comparison to caregivers who receive routine support only. A randomized, controlled trial was conducted, following CONSORT guidelines, with 54 caregivers allocated to parallel intervention (self-help manual) (n = 27) or control (standard support) (n = 27) groups. Resilience was assessed at baseline, post-test (week 8), and follow up (week 12). Intention-to-treat analyses were undertaken. Repeated-measures ANOVA indicated a significant difference in resilience scores between the three time points, showing a large effect. Pairwise comparisons between intervention and control groups indicated resilience to be significantly different between baseline and post-test, and between baseline and follow up, but not between post-test and follow up. Overall, the intervention group showed a slightly greater increase in resilience over time than the control group; however, the time–group interaction was not significant. Guided self-help is helpful in improving caregivers’ resilience and could be used as an adjunct to the limited support provided to carers by mental health nurses and other clinicians

Thermoregulation and Rate of Body Warming During Warm Water (40℃) Immersion in Female Children and Adults

Resort operators often do not allow children to use hot tubs/whirlpools because of the general belief that children cannot tolerate even a short exposure to warm water (40℃). This belief is based on body size characteristics and under developed thermoregulatory responses of children. Therefore, we measured anthropometric, thermoregulatory, and immersion time required to increase core temperature at 38.5℃, on 14 female subjects (7-23 years). All subjects tolerated 10 minutes of immersion safely, but indicated they would have voluntarily exited the water earlier. Warming rates were somewhat related to body type, but did not depend on age. Healthy female children (\u3e7 years) could therefore safely tolerate 5 to 10 minutes of warm water immersion with adult supervision

Single-trial classification of neural responses evoked in rapid serial visual presentation: Effects of stimulus onset asynchrony and stimulus repetition

Abstract-Rapid serial visual presentation (RSVP) tasks, in which participants are presented with a continuous sequence of images in one location, have been used in combination with electroencephalography (EEG) in a variety of Brain-Machine Interface (BMI) applications. The RSVP task is advantageous because it can be performed at a high temporal rate. The rate of the RSVP sequence is controlled by the stimulus onset asynchrony (SOA) between subsequent stimuli. When used within the context of a BMI, an RSVP task with short SOA could increase the information throughput of the system while also allowing for stimulus repetitions. However, reducing the SOA also increases the perceptual degradation caused by presenting two stimuli in close succession, and it decreases the target-to-target interval (TTI), which can increase the cognitive demands of the task. These negative consequences of decreasing the SOA could affect on the EEG signal measured in the task and degrade the performance of the BMI. Here we systematically investigate the effects of SOA and stimulus repetition (r) on single-trial target detection in an RSVP task. Ten healthy volunteers participated in an RSVP task in four conditions that varied in SOA and repetitions (SOA=500 ms, r=1; SOA=250 ms, r=2; SOA=166 ms, r=3; and SOA=100 ms, r=5) while processing time across conditions was controlled. There were two key results: First, when controlling for the number of repetitions, single-trial performance increases when the SOA decreases. Second, when the repetitions were combined, the best performance (AUC=0.967) was obtained with the shortest SOA (100 ms). These results suggest that shortening the SOA in an RSVP task has the benefit of increasing the performance relative to longer SOAs, and it also allows a higher number of repetitions of the stimuli in a limited amount of time

CONTROL ALTERNATIVO DE NEMATODOS EN EL CULTIVO DE TOMATE (Lycopersicon esculentum Mill.), EN CONDICIONES DE INVERNADERO

El experimento se realizó en un invernadero, en la comunidad de Paratodo, Chaco Central, Paraguay, durante los meses de abril a julio del 2008, con el objetivo de hallar un método alternativo, eficiente para el control de nematodos fitoparásitos, para el cultivo de tomate (Lycopersicon esculentum Mill.). El diseño experimental utilizado fue el de bloques completamente al azar, con cinco tratamientos y cuatro repeticiones. Los tratamientos aplicados fueron: Materia orgánica (estiércol bovino + gallinaza), Crotalaria (Crotalaria juncea), barbecho (sin riego), torta de  tártago (Ricinus communis) y el testigo (con riego). Se evaluó el efecto, de estos tratamientos, sobre la población de fitonematodos del cultivo de tomate, específicamente la de Meloidogyne sp. y Helicotylenchus sp., así como el efecto sobre la población de nematodos de vida libre. Se realizaron dos muestreos, el primero antes de instalar los tratamientos, y el segundo, a los tres meses del experimento. Las muestras fueron procesadas en el laboratorio de Nematología, de la división de Fitopatología, de la Facultad de Ciencias Agrarias (FCA), de la Universidad Nacional de Asunción (UNA), empleando los métodos de Cobb y de flotación en azúcar. El tratamiento, que mayor efecto supresivo tuvo, sobre la población de fitonematodos, fue el tratamiento con tártago. Los tratamientos con crotalaria, barbecho y el testigo redujeron satisfactoriamente a la población de Meloidogyne sp., y en menor proporción a la población de Helicotylenchus sp.. El mayor efecto sobre la población de Helicotylenchus sp. tuvo el tratamiento con tártago, pero éste no disminuyó la población de Meloidogyne sp.. Los tratamientos con tártago, materia orgánica y crotalaria aumentaron la población de nematodos de vida libre, mientras que con los demás tratamientos, disminuyó la población de los mismos.

Understanding charge transport in lead iodide perovskite thin-film field-effect transistors

Fundamental understanding of the charge transport physics of hybrid lead halide perovskite semiconductors is important for advancing their use in high-performance optoelectronics. We use field-effect transistors (FETs) to probe the charge transport mechanism in thin films of methylammonium lead iodide (MAPbI$_{3}$). We show that through optimization of thin-film microstructure and source-drain contact modifications, it is possible to significantly minimize instability and hysteresis in FET characteristics and demonstrate an electron field-effect mobility (μ$_{FET}$) of 0.5 cm$^{2}$/Vs at room temperature. Temperature-dependent transport studies revealed a negative coefficient of mobility with three different temperature regimes. On the basis of electrical and spectroscopic studies, we attribute the three different regimes to transport limited by ion migration due to point defects associated with grain boundaries, polarization disorder of the MA$^{+}$ cations, and thermal vibrations of the lead halide inorganic cages.S.P.S. acknowledges funding from the Royal Society London for a Newton Fellowship. B.Y. acknowledges support from China Council Scholarship and Cambridge Overseas Trust. A.S. and R.H.F. acknowledge funding and support from the Engineering and Physical Sciences Research Council (EPSRC) through the India-U.K. APEX project. P.D. acknowledges support from the European Union through the award of a Marie Curie Intra-European Fellowship. X.M. is grateful for the support from the Royal Society. B.N. is grateful for the support from Gates Cambridge and the Winton Program for the Physics of Sustainability. We acknowledge funding from the EPSRC through a program grant (EP/M005143/1). We acknowledge funding from the German Federal Ministry of Education and Research under agreement number 01162525/1. This work was performed in part on the SAXS/WAXS beamline of the Australian Synchrotron, Victoria, Australia (55, 56). C.R.M. acknowledges support from the Australian Research Council (DP13012616)

Examining the early distribution of the artemisinin-resistant Plasmodium falciparum kelch13 R561H mutation in areas of higher transmission in Rwanda

BACKGROUND: Artemisinin resistance mutations in Plasmodium falciparum kelch13 (Pfk13) have begun to emerge in Africa, with Pfk13-R561H being the first reported in Rwanda in 2014, but limited sampling left questions about its early distribution and origin. METHODS: We genotyped P. falciparum positive dried blood spot (DBS) samples from a nationally representative 2014-2015 Rwanda Demographic Health Surveys (DHS) HIV study. DBS were subsampled from DHS sampling clusters with >15% P. falciparum prevalence, as determined by rapid testing or microscopy done during the DHS study (n clusters = 67, n samples = 1873). RESULTS: We detected 476 parasitemias among 1873 residual blood spots from a 2014-2015 Rwanda Demographic Health Survey. We sequenced 351 samples: 341/351 were wild-type (97.03% weighted), and 4 samples (1.34% weighted) harbored R561H that were significantly spatially clustered. Other nonsynonymous mutations found were V555A (3), C532W (1), and G533A (1). CONCLUSIONS: Our study better defines the early distribution of R561H in Rwanda. Previous studies only observed the mutation in Masaka as of 2014, but our study indicates its presence in higher-transmission regions in the southeast of the country at that time

Basic Module Theory over Non-Commutative Rings with Computational Aspects of Operator Algebras

The present text surveys some relevant situations and results where basic Module Theory interacts with computational aspects of operator algebras. We tried to keep a balance between constructive and algebraic aspects.Comment: To appear in the Proceedings of the AADIOS 2012 conference, to be published in Lecture Notes in Computer Scienc