The impact of visual cues and lexical knowledge on the perception of a non-native consonant contrast for Colombian adults

The study investigates the impact of visual cues and lexical knowledge on the identification of a nonnative phonemic contrast. Twenty native Colombians were tested on an identification task involving 16 minimal pairs of English words, produced by four English speakers, contrasting in the presence of /b/ or /v/ in initial or medial position. The test was run in three conditions: audiovisual (AV), audio only (A) or visual only (V). Prior to the identification task, their knowledge of the lexical items was evaluated; they were also recorded while reading the words. Mean identification scores were higher for the AV than the A condition, but V and AV scores not differ. Relative to previous /b/-/v/ studies with Peninsular Spanish speakers, Colombians relied more heavily on visual cues in their identification of /b/-/v/. Although there was a trend for identification scores to be higher for known lexical items, this effect was not statistically significant. Finally, production accuracy for the /b/-/v/ contrast was not correlated with perception accuracy, but production tended to be more accurate in speakers with better lexical knowledge. The visual weighting results suggest that the degree of visual bias in speech perception may be ‘culture-specific’ rather than merely ‘language-specific’

Spectral Sparsification and Regret Minimization Beyond Matrix Multiplicative Updates

In this paper, we provide a novel construction of the linear-sized spectral sparsifiers of Batson, Spielman and Srivastava [BSS14]. While previous constructions required $\Omega(n^4)$ running time [BSS14, Zou12], our sparsification routine can be implemented in almost-quadratic running time $O(n^{2+\varepsilon})$. The fundamental conceptual novelty of our work is the leveraging of a strong connection between sparsification and a regret minimization problem over density matrices. This connection was known to provide an interpretation of the randomized sparsifiers of Spielman and Srivastava [SS11] via the application of matrix multiplicative weight updates (MWU) [CHS11, Vis14]. In this paper, we explain how matrix MWU naturally arises as an instance of the Follow-the-Regularized-Leader framework and generalize this approach to yield a larger class of updates. This new class allows us to accelerate the construction of linear-sized spectral sparsifiers, and give novel insights on the motivation behind Batson, Spielman and Srivastava [BSS14]

The development of clear speech strategies in 9-14 year olds

This study investigated the development of global clear speech strategies of child talkers. Two groups of 20 talkers aged 9-10 (children) and 13-14 (teens) were recorded in pairs while they carried out spot the difference picture tasks, either hearing each other normally (NB condition) or with one talker hearing the other via a three-channel noise vocoder (VOC condition). Acoustic-phonetic analyses focused on the talker having to overcome the communication barrier. Data were compared to those for 20 of the adults in Hazan and Baker (2011) [J.Acoust.Soc, Am, 130, 2139-2152]. The three age groups did not differ in task transaction time for NB, but children took significantly longer to complete the task in VOC than teens or adults who took equally long. Children spoke at a slower speech rate overall than teens, while teens and adults did not differ; all groups significantly reduced their speech rate in VOC relative to NB. Adults hyperarticulated vowels in VOC but children and teens showed only minor adaptations. These results suggest that although 9-10 year olds use some strategies to clarify their speech in difficult conditions, other strategies continue to develop into late adolescence

Do children enhance phonetic contrasts in speech directed to a hearing-impaired peer?

This study examines whether normal-hearing (NH) children enhance phonetic contrasts when speaking to a hearing-impaired (HI) peer. A problem-solving ‘Grid’ task was developed to elicit frequent repetitions of /p/-/b/, /s/-/S/ and /i/-/I/ segmental contrasts and point vowels in communicative spontaneous speech. Eighteen NH children between 9 and 15 years old performed the task once with a NH friend and once with a HI friend. Both category means and within-speaker variability were analysed. Results suggest that although HI interlocutors are likely to find the phonetic contrasts difficult to produce and perceive, children’s HI-directed speech contains little evidence of phonetic category enhancement

Faster Eigenvector Computation via Shift-and-Invert Preconditioning

We give faster algorithms and improved sample complexities for estimating the top eigenvector of a matrix $\Sigma$ -- i.e. computing a unit vector $x$ such that $x^T \Sigma x \ge (1-\epsilon)\lambda_1(\Sigma)$: Offline Eigenvector Estimation: Given an explicit $A \in \mathbb{R}^{n \times d}$ with $\Sigma = A^TA$, we show how to compute an $\epsilon$ approximate top eigenvector in time $\tilde O([nnz(A) + \frac{d*sr(A)}{gap^2} ]* \log 1/\epsilon )$ and $\tilde O([\frac{nnz(A)^{3/4} (d*sr(A))^{1/4}}{\sqrt{gap}} ] * \log 1/\epsilon )$. Here $nnz(A)$ is the number of nonzeros in $A$, $sr(A)$ is the stable rank, $gap$ is the relative eigengap. By separating the $gap$ dependence from the $nnz(A)$ term, our first runtime improves upon the classical power and Lanczos methods. It also improves prior work using fast subspace embeddings [AC09, CW13] and stochastic optimization [Sha15c], giving significantly better dependencies on $sr(A)$ and $\epsilon$. Our second running time improves these further when $nnz(A) \le \frac{d*sr(A)}{gap^2}$. Online Eigenvector Estimation: Given a distribution $D$ with covariance matrix $\Sigma$ and a vector $x_0$ which is an $O(gap)$ approximate top eigenvector for $\Sigma$, we show how to refine to an $\epsilon$ approximation using $O(\frac{var(D)}{gap*\epsilon})$ samples from $D$. Here $var(D)$ is a natural notion of variance. Combining our algorithm with previous work to initialize $x_0$, we obtain improved sample complexity and runtime results under a variety of assumptions on $D$. We achieve our results using a general framework that we believe is of independent interest. We give a robust analysis of the classic method of shift-and-invert preconditioning to reduce eigenvector computation to approximately solving a sequence of linear systems. We then apply fast stochastic variance reduced gradient (SVRG) based system solvers to achieve our claims.Comment: Appearing in ICML 2016. Combination of work in arXiv:1509.05647 and arXiv:1510.0889

Laboratory evaluation of diatomaceous earth against main stored product insects

The sensitivity of the main external and internal stored product insect pests to the commercial formulation of Detia Degesch Diatomaceous Earth – DDDE - Inerto (DE) was studied in laboratory experiments. The tested insects were adults of internal feeders Sitophilus oryzae Rhyzopertha dominica and external feeders Oryzaephilus surinamensis, Tribolium castaneum, and larvae (third instar) of T.castaneum. The DE was applied to wheat grain of 12% moisture content at concentrations of 0.5, 1.0, 2.0 and 4.0 g/kg of grain. The treated and untreated (control) grain were kept at 28°C and 65 ± 5% r.h. The numbers of dead and survived insects were counted two, three and four weeks after treatment. The number of adult progeny was counted nine weeks after treatment. At a concentration of 0.5 g/kg, mortality of S. oryzae and O. surinamensis after three weeks of exposure to DE were 92 and 86%, respectively. In contrast, mortality of T. castaneum and R. dominica adults was 3 and 37%, respectively. Progeny production of O. surinamensis and T. castaneum at a concentration of 2 g/kg was negligible, since only few individuals were recorded nine weeks after treatment, in comparison with the high progeny production in the control grain. The progeny of S. oryzae was also reduced. In contrast, for R. dominica was reduced only twice, in comparison with the control. In the case of T. castaneum larvae, at a concentration of 2 g/kg, after 4 weeks of exposure, 37% of the larvae emerged to adults, compared with 95% in control. Nine weeks after treatment, the number of F1adults was 100% suppressed. DE efficacy was similar at 4 g/kg. Based on the findings of the present study, the efficacy of the tested DE was influenced by DE concentration, insect species, developmental stage and exposure interval to the treated commodity.Keywords: Diatomaceous earth, Stored product insects, Wheat grai

The Computational Power of Optimization in Online Learning

We consider the fundamental problem of prediction with expert advice where the experts are "optimizable": there is a black-box optimization oracle that can be used to compute, in constant time, the leading expert in retrospect at any point in time. In this setting, we give a novel online algorithm that attains vanishing regret with respect to $N$ experts in total $\widetilde{O}(\sqrt{N})$ computation time. We also give a lower bound showing that this running time cannot be improved (up to log factors) in the oracle model, thereby exhibiting a quadratic speedup as compared to the standard, oracle-free setting where the required time for vanishing regret is $\widetilde{\Theta}(N)$. These results demonstrate an exponential gap between the power of optimization in online learning and its power in statistical learning: in the latter, an optimization oracle---i.e., an efficient empirical risk minimizer---allows to learn a finite hypothesis class of size $N$ in time $O(\log{N})$. We also study the implications of our results to learning in repeated zero-sum games, in a setting where the players have access to oracles that compute, in constant time, their best-response to any mixed strategy of their opponent. We show that the runtime required for approximating the minimax value of the game in this setting is $\widetilde{\Theta}(\sqrt{N})$, yielding again a quadratic improvement upon the oracle-free setting, where $\widetilde{\Theta}(N)$ is known to be tight

Improvement of phosphine fumigation by the use of Speedbox

Today, phosphine is turning to be a major fumigant for controlling insects in stored products. However, few limitations, such as low temperatures and relatively long exposure time, limit the phosphine use. In order to improve phosphine application, a special devise, containing a heater and a ventilator, called "Speedbox" has been developed by Detia Degesch GmbH Germany. For studying the effectiveness of phosphine fumigation using Speedbox, we have conducted two kinds of experiments: one in a fumigation room (Pilot) and other in commercial warehouse. For pilot fumigation, adults, pupae and late larvae of Sitophilus oryzae, Rhyzopertha dominica, Oryzaephilus surinamensis, Trogoderma granarium and Callosobruchus maculatus, and all stages of Tribolium castaneum Herbst, Plodia interpunctella and Ephestia cautella were used as test insects. One to three Degesch Plates (about 2-6 g of phosphine gas per m3) were used. Exposure time was 1 to 3 days. The phosphine concentrtion was monitored by Bedfont device model 415. At 4 g/m3 for 48 ha maximum of phosphine concentration of 1460 ppm was reached. The total mortality of all tested insects and stages was recorded, except the eggs of E. cautella (98%). The commercial stack fumigation was done at the dosages of 2-4 g/m3, exposure time of 2-4 days and commodity temperatures of 6-17ºC. At a target concentration of 4 g/m3, 2 hours after beginning of the treatment, the concentration of the gas has reached 414 ppm, with a maximum of 1480 ppm. The total mortality of tested insects at adult, late larvae and pupae stages was recorded. The use of Speedbox allows one-day decrease in the plates degassing time, recirculation of the gas and its event distribution in the treated space and controlling major stored product insects for shorter exposure time at low temperatures. Keywords: Fumigation; Posphine; Speedbox; Stored-product insect