Estimating a Polya frequency function_2

We consider the non-parametric maximum likelihood estimation in the class of Polya frequency functions of order two, viz. the densities with a concave logarithm. This is a subclass of unimodal densities and fairly rich in general. The NPMLE is shown to be the solution to a convex programming problem in the Euclidean space and an algorithm is devised similar to the iterative convex minorant algorithm by Jongbleod (1999). The estimator achieves Hellinger consistency when the true density is a PFF_2 itself.Comment: Published at http://dx.doi.org/10.1214/074921707000000184 in the IMS Lecture Notes Monograph Series (http://www.imstat.org/publications/lecnotes.htm) by the Institute of Mathematical Statistics (http://www.imstat.org

Constitutional Amendment After the Senate Reference and the Prospects for Electoral Reform

The new federal government committed that 2015 would be the last election under the first past the post (“FPTP”) system used since 1867. If the federal electoral system does change, it will be a break from the recent politics of reform. Over the last decade, numerous attempts to reform provincial electoral systems have failed. The additional potential hurdle facing the federal government, which was not relevant for the provinces, is the uncertainty relating to the rules on constitutional amendment, particularly in light of the Reference re Senate Reform. The central questions I address in this article are whether federal electoral reform requires recourse to the formal amendment rules in Part V of the Constitution Act, 1982 and, if so, whether provincial consent is required. Canada famously has one of the democratic world’s most rigid regimes for constitutional amendment. If electoral reform requires provincial consent, then it is likely dead on arrival. While it is formally possible to amend the Constitution even where federal-provincial agreement is obligatory, it is likely to be constructively unamendable in the absence of a new round of mega-constitutional negotiations

Gravitational decay of the Z-boson

We study the decay process of the Z boson to a photon and a graviton. The most general form of the on-shell amplitude, subject to the constraints due to the conservation of the electromagnetic and the energy-momentum tensor, is determined. The amplitude is expressed in terms of three form factors, two of which are CP-odd while one is CP-even. The latter, which is the only non-zero form factor at the one-loop level, is computed in the standard model and the decay rate is determined.Comment: 30 pages, Latex, uses Axodraw. (Some typographical errors corrected, and some references added in the new version.

Citizenship and the First-Generation Limitation in Canada

This article considers the current Canadian regime for citizenship by descent and what is known as the “first-generation limitation.” In 2009, Parliament legislated to limit the transmission of citizenship by descent. Known as the “first-generation limitation,” the new rules mean that a Canadian parent is only entitled to pass on their citizenship to their children born abroad if the parent themselves became a citizen by birth inside Canada or by naturalization. In other words, if an individual acquired Canadian citizenship by descent, they are not entitled to pass on their citizenship to their children unless those children are born in Canada. The imposition of the first-generation limitation was controversial, as it is much more restrictive than the previous Canadian rules or those in many comparable jurisdictions. This article outlines the operation of the current Canadian rules around citizenship, analyzes the first-generation limitation, and sets out relevant international comparisons. In evaluating the current legal regime in light of debates about the principles of jus soli, jus sanguinis, and jus nexi, we conclude that the current legal regime is overly restrictive. There are potential alternatives that would better meet the underlying values of Canadian citizenship law. Building on the foundations of jus soli, jus sanguinis, and jus nexi, we have identified three main policy options that respond to the tensions raised by the indefinite transmission of citizenship by descent in Canada: (1) a parental residency exception; (2) an adapted naturalization application, and (3) a birth registration exception. In our assessment, any of these three options would be preferable to the status quo or the pre-2009 rules. Dans le présent article, nous examinons le régime canadien actuel en matière de citoyenneté par filiation et ce que l’on appelle la « limitation à la première génération ». En 2009, le Parlement a légiféré pour limiter la transmission de la citoyenneté par filiation. Connues sous le nom de « limitation de la première génération », les nouvelles règles signifient qu’un parent canadien n’a le droit de transmettre sa citoyenneté à ses enfants nés à l’étranger que si le parent est lui-même devenu citoyen par naissance au Canada ou par naturalisation. En d’autres termes, si une personne a acquis la citoyenneté canadienne par filiation, elle n’a pas le droit de transmettre sa citoyenneté à ses enfants, sauf si ces derniers sont nés au Canada. L’imposition de cette limite de la première génération a suscité la controverse, car elle est beaucoup plus restrictive que les règles canadiennes précédentes ou que celles de nombreuses juridictions comparables. Dans le présent article, nous décrivons le fonctionnement des règles canadiennes actuelles en matière de citoyenneté, analysons la limite de la première génération et établissons des comparaisons internationales pertinentes. En évaluant le régime juridique actuel à la lumière des débats sur les principes du jus soli (droit du sol), du jus sanguinis (droit du sang) et du jus nexi (droit par filiation), nous concluons que le régime juridique actuel est trop restrictif. Il existe d’autres possibilités qui répondraient mieux aux valeurs sousjacentes du droit de la citoyenneté canadienne. En nous appuyant sur les fondements du jus soli, du jus sanguinis et du jus nexi, nous avons identifié trois grandes options politiques qui répondent aux tensions soulevées par la transmission indéfinie de la citoyenneté par filiation au Canada : (1) une exception de résidence parentale ; (2) une demande de naturalisation adaptée, et (3) une exception d’enregistrement des naissances. Selon nous, chacune de ces trois options serait préférable au statu quo ou aux règles antérieures à 2009

Computational modeling of TC0583 as a putative component of the Chlamydia muridarum V-type ATP synthase complex and assessment of its protective capabilities as a vaccine antigen.

Numerous Chlamydia trachomatis proteins have been identified as potential subunit vaccines, of which the major outer-membrane protein (MOMP) has, so far, proven the most efficacious. Recently, subunit A of the V-type ATP synthase (ATPase; TC0582) complex was shown to elicit partial protection against infection. Computational modeling of a neighboring gene revealed a novel subunit of the V-type ATPase (TC0583). To determine if this newly identified subunit could induce protection and/or enhance the partial protection provided by subunit A alone, challenge studies were performed using a combination of these recombinant proteins. The TC0583 subunit alone and concurrently with TC0582, was used to vaccinate BALB/c mice utilizing CpG-1826 and Montanide ISA 720 VG as adjuvants. Vaccinated animals were challenged intranasally with Chlamydia muridarum and the course of the infection was followed. Mice immunized with individual antigens showed minimal alleviation of body weight reduction; however, mice immunized with TC0583 and TC0582 in combination, displayed weight loss levels close to those observed with MOMP. Importantly, immunization with a combination of recombinant subunit proteins reduced chlamydial inclusion forming units by approximately a log-fold. These protection levels support that, these highly conserved Chlamydia proteins, in combination with other antigens, may serve as potential vaccine candidates

Revealing static and dynamic modular architecture of the eukaryotic protein interaction network

In an effort to understand the dynamic organization of the protein interaction network and its role in the regulation of cell behavior, positioning of proteins into specific network localities was studied with respect to their expression dynamics. First, we find that constitutively expressed and dynamically co-regulated proteins cluster in distinct functionally specialized network neighborhoods to form static and dynamic functional modules, respectively. Then, we show that whereas dynamic modules are mainly responsible for condition-dependent regulation of cell behavior, static modules provide robustness to the cell against genetic perturbations or protein expression noise, and therefore may act as buffers of evolutionary as well as population variations in cell behavior. Observations in this study refine the previously proposed model of dynamic modularity in the protein interaction network, and propose a link between the evolution of gene expression regulation and biological robustness

Sparse Attentive Backtracking: Temporal CreditAssignment Through Reminding

Learning long-term dependencies in extended temporal sequences requires credit assignment to events far back in the past. The most common method for training recurrent neural networks, back-propagation through time (BPTT), requires credit information to be propagated backwards through every single step of the forward computation, potentially over thousands or millions of time steps. This becomes computationally expensive or even infeasible when used with long sequences. Importantly, biological brains are unlikely to perform such detailed reverse replay over very long sequences of internal states (consider days, months, or years.) However, humans are often reminded of past memories or mental states which are associated with the current mental state. We consider the hypothesis that such memory associations between past and present could be used for credit assignment through arbitrarily long sequences, propagating the credit assigned to the current state to the associated past state. Based on this principle, we study a novel algorithm which only back-propagates through a few of these temporal skip connections, realized by a learned attention mechanism that associates current states with relevant past states. We demonstrate in experiments that our method matches or outperforms regular BPTT and truncated BPTT in tasks involving particularly long-term dependencies, but without requiring the biologically implausible backward replay through the whole history of states. Additionally, we demonstrate that the proposed method transfers to longer sequences significantly better than LSTMs trained with BPTT and LSTMs trained with full self-attention.Comment: To appear as a Spotlight presentation at NIPS 201

Tracking Dengue Epidemics using Twitter Content Classification and Topic Modelling

Detecting and preventing outbreaks of mosquito-borne diseases such as Dengue and Zika in Brasil and other tropical regions has long been a priority for governments in affected areas. Streaming social media content, such as Twitter, is increasingly being used for health vigilance applications such as flu detection. However, previous work has not addressed the complexity of drastic seasonal changes on Twitter content across multiple epidemic outbreaks. In order to address this gap, this paper contrasts two complementary approaches to detecting Twitter content that is relevant for Dengue outbreak detection, namely supervised classification and unsupervised clustering using topic modelling. Each approach has benefits and shortcomings. Our classifier achieves a prediction accuracy of about 80\% based on a small training set of about 1,000 instances, but the need for manual annotation makes it hard to track seasonal changes in the nature of the epidemics, such as the emergence of new types of virus in certain geographical locations. In contrast, LDA-based topic modelling scales well, generating cohesive and well-separated clusters from larger samples. While clusters can be easily re-generated following changes in epidemics, however, this approach makes it hard to clearly segregate relevant tweets into well-defined clusters.Comment: Procs. SoWeMine - co-located with ICWE 2016. 2016, Lugano, Switzerlan