Pseudorandomness for Regular Branching Programs via Fourier Analysis

We present an explicit pseudorandom generator for oblivious, read-once, permutation branching programs of constant width that can read their input bits in any order. The seed length is $O(\log^2 n)$, where $n$ is the length of the branching program. The previous best seed length known for this model was $n^{1/2+o(1)}$, which follows as a special case of a generator due to Impagliazzo, Meka, and Zuckerman (FOCS 2012) (which gives a seed length of $s^{1/2+o(1)}$ for arbitrary branching programs of size $s$). Our techniques also give seed length $n^{1/2+o(1)}$ for general oblivious, read-once branching programs of width $2^{n^{o(1)}}$, which is incomparable to the results of Impagliazzo et al.Our pseudorandom generator is similar to the one used by Gopalan et al. (FOCS 2012) for read-once CNFs, but the analysis is quite different; ours is based on Fourier analysis of branching programs. In particular, we show that an oblivious, read-once, regular branching program of width $w$ has Fourier mass at most $(2w^2)^k$ at level $k$, independent of the length of the program.Comment: RANDOM 201

From Low-Distortion Norm Embeddings to Explicit Uncertainty Relations and Efficient Information Locking

The existence of quantum uncertainty relations is the essential reason that some classically impossible cryptographic primitives become possible when quantum communication is allowed. One direct operational manifestation of these uncertainty relations is a purely quantum effect referred to as information locking. A locking scheme can be viewed as a cryptographic protocol in which a uniformly random n-bit message is encoded in a quantum system using a classical key of size much smaller than n. Without the key, no measurement of this quantum state can extract more than a negligible amount of information about the message, in which case the message is said to be "locked". Furthermore, knowing the key, it is possible to recover, that is "unlock", the message. In this paper, we make the following contributions by exploiting a connection between uncertainty relations and low-distortion embeddings of L2 into L1. We introduce the notion of metric uncertainty relations and connect it to low-distortion embeddings of L2 into L1. A metric uncertainty relation also implies an entropic uncertainty relation. We prove that random bases satisfy uncertainty relations with a stronger definition and better parameters than previously known. Our proof is also considerably simpler than earlier proofs. We apply this result to show the existence of locking schemes with key size independent of the message length. We give efficient constructions of metric uncertainty relations. The bases defining these metric uncertainty relations are computable by quantum circuits of almost linear size. This leads to the first explicit construction of a strong information locking scheme. Moreover, we present a locking scheme that is close to being implementable with current technology. We apply our metric uncertainty relations to exhibit communication protocols that perform quantum equality testing.Comment: 60 pages, 5 figures. v4: published versio

Exploring sex differences in attitudes towards the descriptive and substantive representation of women

This article unpacks the rationales that might be behind individual-level support for the idea that there ought to be more women present in political institutions. We outline two distinct rationales: the substantive position that sees an increase in women’s descriptive representation as important in bringing about a subsequent improvement in women’s substantive representation, or the justice-plus position that sees an increase in the descriptive representation of women as important for reasons of justice or other symbolic benefits. We find that women are more likely than men to support an increase in descriptive representation and that women are more likely to hold both the view that an increase in descriptive representation was desirable and that such an increase would improve the representation of women’s political interests. Men are found to be more likely to support an increase in descriptive representation but not relate descriptive representation to substantive representation in any way: the justice-plus rationale

Development of the (d,n) proton-transfer reaction in inverse kinematics for structure studies

Transfer reactions have provided exciting opportunities to study the structure of exotic nuclei and are often used to inform studies relating to nucleosynthesis and applications. In order to benefit from these reactions and their application to rare ion beams (RIBs) it is necessary to develop the tools and techniques to perform and analyze the data from reactions performed in inverse kinematics, that is with targets of light nuclei and heavier beams. We are continuing to expand the transfer reaction toolbox in preparation for the next generation of facilities, such as the Facility for Rare Ion Beams (FRIB), which is scheduled for completion in 2022. An important step in this process is to perform the (d,n) reaction in inverse kinematics, with analyses that include Q-value spectra and differential cross sections. In this way, proton-transfer reactions can be placed on the same level as the more commonly used neutron-transfer reactions, such as (d,p), (9Be,8Be), and (13C,12C). Here we present an overview of the techniques used in (d,p) and (d,n), and some recent data from (d,n) reactions in inverse kinematics using stable beams of 12C and 16O.Comment: 9 pages, 4 figures, presented at the XXXV Mazurian Lakes Conference on Physics, Piaski, Polan

It Takes Two–Skilled Recognition of Objects Engages Lateral Areas in Both Hemispheres

Our object recognition abilities, a direct product of our experience with objects, are fine-tuned to perfection. Left temporal and lateral areas along the dorsal, action related stream, as well as left infero-temporal areas along the ventral, object related stream are engaged in object recognition. Here we show that expertise modulates the activity of dorsal areas in the recognition of man-made objects with clearly specified functions. Expert chess players were faster than chess novices in identifying chess objects and their functional relations. Experts' advantage was domain-specific as there were no differences between groups in a control task featuring geometrical shapes. The pattern of eye movements supported the notion that experts' extensive knowledge about domain objects and their functions enabled superior recognition even when experts were not directly fixating the objects of interest. Functional magnetic resonance imaging (fMRI) related exclusively the areas along the dorsal stream to chess specific object recognition. Besides the commonly involved left temporal and parietal lateral brain areas, we found that only in experts homologous areas on the right hemisphere were also engaged in chess specific object recognition. Based on these results, we discuss whether skilled object recognition does not only involve a more efficient version of the processes found in non-skilled recognition, but also qualitatively different cognitive processes which engage additional brain areas

A multiplicative hazard regression model to assess the risk of disease transmission at hospital during community epidemics

<p>Abstract</p> <p>Background</p> <p>During community epidemics, infections may be imported within hospital and transmitted to hospitalized patients. Hospital outbreaks of communicable diseases have been increasingly reported during the last decades and have had significant consequences in terms of patient morbidity, mortality, and associated costs. Quantitative studies are thus needed to estimate the risks of communicable diseases among hospital patients, taking into account the epidemiological process outside, hospital and host-related risk factors of infection and the role of other patients and healthcare workers as sources of infection.</p> <p>Methods</p> <p>We propose a multiplicative hazard regression model to analyze the risk of acquiring a communicable disease by patients at hospital. This model derives from epidemiological data on communicable disease epidemics in the community, hospital ward, patient susceptibility to infection, and exposure of patients to infection at hospital. The model estimates the relative effect of each of these factors on a patient's risk of communicable disease.</p> <p>Results</p> <p>Using individual data on patients and health care workers in a teaching hospital during the 2004-2005 influenza season in Lyon (France), we show the ability of the model to assess the risk of influenza-like illness among hospitalized patients. The significant effects on the risk of influenza-like illness were those of old age, exposure to infectious patients or health care workers, and a stay in a medical care unit.</p> <p>Conclusions</p> <p>The proposed multiplicative hazard regression model could be an interesting epidemiological tool to quantify the risk of communicable disease at hospital during community epidemics and the uncertainty inherent in such quantification. Furthermore, key epidemiological, environmental, host, or exposure factors that influence this risk can be identified.</p

Enhancements Are Blackbox Non-Trivial: Impossibility of Enhanced Trapdoor Permutations from Standard Trapdoor Permutations

Trapdoor permutations (TDP) are a fundamental primitive in cryptography. Over the years, several variants of this notion have emerged as a result of various applications. However, it is not clear whether these variants may be based on the standard notion of TDPs. We study the question of whether enhanced trapdoor permutations can be based on classical trapdoor permutations. The main motivation of our work is in the context of existing TDP-based constructions of oblivious transfer and non-interactive zero-knowledge protocols, which require enhancements to the classical TDP notion. We prove that these enhancements are non-trivial, in the sense that there does not exist fully blackbox constructions of enhanced TDPs from classical TDPs. At a technical level, we show that the enhanced TDP security of any construction in the random TDP oracle world can be broken via a polynomial number of queries to the TDP oracle as well as a weakening oracle, which provides inversion with respect to randomness. We also show that the standard one-wayness of a random TDP oracle stays intact in the presence of this weakening oracle

The effect of HIV on morbidity and mortality in children with severe malarial anaemia

<p>Abstract</p> <p>Background</p> <p>Malaria and HIV are common causes of mortality in sub-Saharan Africa. The effect of HIV infection on morbidity and mortality in children with severe malarial anaemia was assessed.</p> <p>Methods</p> <p>Children <5 years old were followed as part of a prospective cohort study to assess the transfusion-associated transmission of blood-borne pathogens at Mulago Hospital, Kampala, Uganda. All children were hospitalized with a diagnosis of severe malarial anaemia requiring blood transfusion. Survival to different time points post-transfusion was compared between HIV-infected and uninfected children. Generalized estimating equations were used to analyse repeated measurement outcomes of morbidity, adjusting for confounders.</p> <p>Findings</p> <p>Of 847 children, 78 (9.2%) were HIV-infected. Median follow-up time was 162 days (inter-quartile range: 111, 169). HIV-infected children were more likely to die within 7 days (Hazard ratio [HR] = 2.86, 95% Confidence interval [CI] 1.30–6.29, P = 0.009) and within 28 days (HR = 3.70, 95% CI 1.91–7.17, P < 0.001) of an episode of severe malarial anaemia, and were more likely to die in the 6 months post-transfusion (HR = 5.70, 95% CI 3.54–9.16, P < 0.001) compared to HIV-uninfected children. HIV-infected children had more frequent re-admissions due to malaria within 28 days (Incidence rate ratio (IRR) = 3.74, 95% CI 1.41–9.90, P = 0.008) and within 6 months (IRR = 2.66, 95% CI 1.17 – 6.07, P = 0.02) post-transfusion than HIV-uninfected children.</p> <p>Conclusion</p> <p>HIV-infected children with severe malarial anaemia suffered higher all-cause mortality and malaria-related mortality than HIV-uninfected children. Children with HIV and malaria should receive aggressive treatment and further evaluation of their HIV disease, particularly with regard to cotrimoxazole prophylaxis and antiretroviral therapy.</p