Question-Context Alignment and Answer-Context Dependencies for Effective Answer Sentence Selection

Answer sentence selection (AS2) in open-domain question answering finds answer for a question by ranking candidate sentences extracted from web documents. Recent work exploits answer context, i.e., sentences around a candidate, by incorporating them as additional input string to the Transformer models to improve the correctness scoring. In this paper, we propose to improve the candidate scoring by explicitly incorporating the dependencies between question-context and answer-context into the final representation of a candidate. Specifically, we use Optimal Transport to compute the question-based dependencies among sentences in the passage where the answer is extracted from. We then represent these dependencies as edges in a graph and use Graph Convolutional Network to derive the representation of a candidate, a node in the graph. Our proposed model achieves significant improvements on popular AS2 benchmarks, i.e., WikiQA and WDRASS, obtaining new state-of-the-art on all benchmarks.Comment: final copy for INTERSPEECH 202

Containment and equivalence of weighted automata: Probabilistic and max-plus cases

This paper surveys some results regarding decision problems for probabilistic and max-plus automata, such as containment and equivalence. Probabilistic and max-plus automata are part of the general family of weighted automata, whose semantics are maps from words to real values. Given two weighted automata, the equivalence problem asks whether their semantics are the same, and the containment problem whether one is point-wise smaller than the other one. These problems have been studied intensively and this paper will review some techniques used to show (un)decidability and state a list of open questions that still remain

Interferon Production and Signaling Pathways Are Antagonized during Henipavirus Infection of Fruit Bat Cell Lines

Bats are natural reservoirs for a spectrum of infectious zoonotic diseases including the recently emerged henipaviruses (Hendra and Nipah viruses). Henipaviruses have been observed both naturally and experimentally to cause serious and often fatal disease in many different mammal species, including humans. Interestingly, infection of the flying fox with henipaviruses occurs in the absence of clinical disease. The extreme variation in the disease pattern between humans and bats has led to an investigation into the effects of henipavirus infection on the innate immune response in bat cell lines. We report that henipavirus infection does not result in the induction of interferon expression, and the viruses also inhibit interferon signaling. We also confirm that the interferon production and signaling block in bat cells is not due to differing viral protein expression levels between human and bat hosts. This information, in addition to the known lack of clinical signs in bats following henipavirus infection, suggests that bats control henipavirus infection by an as yet unidentified mechanism, not via the interferon response. This is the first report of henipavirus infection in bat cells specifically investigating aspects of the innate immune system

Whole Genomes of Chandipura Virus Isolates and Comparative Analysis with Other Rhabdoviruses

The Chandipura virus (CHPV) belonging to the Vesiculovirus genus and Rhabdoviridae family, has recently been associated with a number of encephalitis epidemics, with high mortality in children, in different parts of India. No full length genome sequences of CHPV isolates were available in GenBank and little is known about the molecular markers for pathogenesis. In the present study, we provide the complete genomic sequences of four isolates from epidemics during 2003–2007. These sequences along with the deduced sequence of the prototype isolate of 1965 were analysed using phylogeny, motif search, homology modeling and epitope prediction methods. Comparison with other rhaboviruses was also done for functional extrapolations. All CHPV isolates clustered with the Isfahan virus and maintained several functional motifs of other rhabdoviruses. A notable difference with the prototype vesiculovirus, Vesicular Stomatitis Virus was in the L-domain flanking sequences of the M protein that are known to be crucial for interaction with host proteins. With respect to the prototype isolate, significant additional mutations were acquired in the 2003–2007 isolates. Several mutations in G mapped onto probable antigenic sites. A mutation in N mapped onto regions crucial for N-N interaction and a putative T-cell epitope. A mutation in the Casein kinase II phosphorylation site in P may attribute to increased rates of phosphorylation. Gene junction comparison revealed changes in the M-G junction of all the epidemic isolates that may have implications on read-through and gene transcription levels. The study can form the basis for further experimental verification and provide additional insights into the virulence determinants of the CHPV

Posterior listhesis of a lumbar vertebra in spinal tuberculosis

The management of spinal tuberculosis, especially in children, is controversial. In children, vertebral destruction is more severe than adults because of the cartilaginous nature of their bone. Modern chemotherapy has significantly decreased mortality in spinal tuberculosis, but morbidity remains high. Without early surgery, patients can develop severe kyphosis leading to respiratory insufficiency, painful costopelvic impingement and paraplegia. Lumbar kyphosis results in early degenerative lumbar canal stenosis and is cosmetically unacceptable. We report a paediatric case of atypical spinal tuberculosis demonstrating the need for early surgical intervention to prevent significant spinal instability and neurologic deficit. A 12-year-old girl presented with increasing ambulatory difficulty and double incontinence 4 months after initiating treatment for pulmonary tuberculosis. There was no history of traumatic injury. Examination revealed severe lower limb neurologic deficit, with hypotonia, areflexia, marked sensory loss, and grade 0/5 power in both lower limbs. Plain radiographs and magnetic resonance imaging (MRI) demonstrated grade IV posterior listhesis of the L2 vertebral body over L3, cauda equina compression and bilateral psoas abscesses. Erosion of both the body and pedicle of L2 was observed. Both serology and pus drained from the psoas abscesses were negative for microorganisms. The patient underwent an L2 vertebrectomy via a left retroperitoneal approach. A titanium cage packed with autologous bone graft was inserted, and the spine was stabilized by fixation with screw and rods. Histopathology confirmed a diagnosis of tuberculosis. Eighteen months following the procedure, the patient has regained some power in her right leg and has completed her course of anti-tuberculous chemotherapy, but remains wheelchair-bound. To our knowledge, this is the first reported case of posterior listhesis secondary to spinal tuberculosis. Here, we discuss the possible management options in such a case, and the indications for surgery. As the global HIV/AIDS epidemic causes a resurgence in tuberculosis, increased awareness among the medical community regarding the atypical presentations of spinal tuberculosis is necessitated; both in the developing world where advanced clinical presentations are common, and in the developed world where spinal tuberculosis is an often-neglected diagnosis