Effect of transients in nuclear fission on multiplicity of prescission neutrons

Transients in the fission of highly excited nuclei are studied in the framework of the Langevin equation. Time-dependent fission widths are calculated which show that after the initial transients, a steady flow towards the scission point is established not only for nuclei which have fission barriers but also for nuclei which have no fission barrier. It is shown from a comparison of the transient time and the fission life time that fission changes from a diffusive to a transient dominated process over a certain transition region as a function of the spin of the fissioning nucleus. Multiplicities of prescission neutrons are calculated in a statistical model with as well as without a single swoop description of fission and they are found to differ in the transition region. We however find that the difference is marginal and hence a single swoop picture of fission though not strictly valid in the transition region can still be used in the statistical model calculations.Comment: 15 pages including 7 figures, to appear in The European Physical Journal

Quest for consistent modelling of statistical decay of the compound nucleus

A statistical model description of heavy ion induced fusion-fission reactions is presented where shell effects, collective enhancement of level density, tilting away effect of compound nuclear spin and dissipation are included. It is shown that the inclusion of all these effects provides a consistent picture of fission where fission hindrance is required to explain the experimental values of both pre-scission neutron multiplicities and evaporation residue cross-sections in contrast to some of the earlier works where a fission hindrance is required for pre-scission neutrons but a fission enhancement for evaporation residue cross-sections.Comment: 14 pages, 2 figure

Alleviating the inconsistencies in modelling decay of fissile compound nuclei

This work attempts to overcome the existing inconsistencies in modelling decay of fissile nucleus by inclusion of important physical effects in the model and through a systematic analysis of a large set of data over a wide range of CN mass (ACN). The model includes shell effect in the level density (LD) parameter, shell correction in the fission barrier, effect of the orientation degree of freedom of the CN spin (Kor), collective enhancement of level density (CELD) and dissipation in fission. Input parameters are not tuned to reproduce observables from specific reaction(s) and the reduced dissipation coefficient is treated as the only adjustable parameter. Calculated evaporation residue (ER) cross sections, fission cross sections and particle, i.e. neutron, proton and alpha-particle, multiplicities are compared with data covering ACN = 156-248. The model produces reasonable fits to ER and fission excitation functions for all the reactions considered in this work. Pre-scission neutron multiplicities are underestimated by the calculation beyond ACN~200. An increasingly higher value of pre-saddle dissipation strength is required to reproduce the data with increasing ACN. Proton and alpha-particle multiplicities, measured in coincidence with both ERs and fission fragments, are in qualitative agreement with model predictions. The present work mitigates the existing inconsistencies in modelling statistical decay of the fissile CN to a large extent.Comment: 15 pages, 9 figure

Complete absence of localization in a family of disordered lattices

We present analytically exact results to show that, certain quasi one-dimensional lattices where the building blocks are arranged in a random fashion, can have an absolutely continuous part in the energy spectrum when special correlations are introduced among some of the parameters describing the corresponding Hamiltonians. We explicitly work out two prototype cases, one being a disordered array of a simple diamond network and isolated dots, and the other an array of triangular plaquettes and dots. In the latter case, a magnetic flux threading each plaquette plays a crucial role in converting the energy spectrum into an absolutely continuous one. A flux controlled enhancement in the electronic transport is an interesting observation in the triangle-dot system that may be useful while considering prospective devices. The analytical findings are comprehensively supported by extensive numerical calculations of the density of states and transmission coefficient in each case.Comment: 6 pages, 6 figures, epl draf

Exploring the role of therapeutic drug monitoring and regular supervision in optimizing quality of life in patients of bipolar affective disorder receiving lithium therapy in a tertiary care teaching hospital: a prospective observational study

Background: Lithium is considered first line drug effective in treating manic and mixed episodes of bipolar affective disorders throughout the globe. But the chronic and heterogenous nature of disease, along with toxicity of lithium often make patients non-adherent to medication as well as diminished health related quality of life. Present study was done to find out the prospect of regular supervision and follow up with therapeutic drug monitoring in optimization of lithium therapy based on health-related quality of life outcomes.Methods: It was a prospective, non-randomized, observational study of a cohort of subjects who are suffering from bipolar affective disorders and on lithium therapy. Patients were regularly followed up with therapeutic drug monitoring and personalized interview with questionnaires like WHO Quality of Life Score (QOL-Bref), Montgomery-Asberg Depression Scale (MADRS) and Medication Adherence Rating Scale (MARS).Results: Results revealed there was significant improvement in health-related quality of life of patients who were monitored with therapeutic drug monitoring and prescribed lithium therapy.Conclusions: Hence to maintain patients’ quality of life improved throughout the cycle of bipolar disorder spectrum, regular follow-up visits with monitoring of serum levels of lithium is needed, so that adverse effects would be minimal and adherence to medication become optimal. These optimal dosing resulting in optimal benefit to patients can be achieved with the involvement of clinical pharmacological consultation

A Hybrid Machine Translation Framework for an Improved Translation Workflow

Over the past few decades, due to a continuing surge in the amount of content being translated and ever increasing pressure to deliver high quality and high throughput translation, translation industries are focusing their interest on adopting advanced technologies such as machine translation (MT), and automatic post-editing (APE) in their translation workflows. Despite the progress of the technology, the roles of humans and machines essentially remain intact as MT/APE are moving from the peripheries of the translation field closer towards collaborative human-machine based MT/APE in modern translation workflows. Professional translators increasingly become post-editors correcting raw MT/APE output instead of translating from scratch which in turn increases productivity in terms of translation speed. The last decade has seen substantial growth in research and development activities on improving MT; usually concentrating on selected aspects of workflows starting from training data pre-processing techniques to core MT processes to post-editing methods. To date, however, complete MT workflows are less investigated than the core MT processes. In the research presented in this thesis, we investigate avenues towards achieving improved MT workflows. We study how different MT paradigms can be utilized and integrated to best effect. We also investigate how different upstream and downstream component technologies can be hybridized to achieve overall improved MT. Finally we include an investigation into human-machine collaborative MT by taking humans in the loop. In many of (but not all) the experiments presented in this thesis we focus on data scenarios provided by low resource language settings.Aufgrund des stetig ansteigenden Übersetzungsvolumens in den letzten Jahrzehnten und gleichzeitig wachsendem Druck hohe Qualität innerhalb von kürzester Zeit liefern zu müssen sind Übersetzungsdienstleister darauf angewiesen, moderne Technologien wie Maschinelle Übersetzung (MT) und automatisches Post-Editing (APE) in den Übersetzungsworkflow einzubinden. Trotz erheblicher Fortschritte dieser Technologien haben sich die Rollen von Mensch und Maschine kaum verändert. MT/APE ist jedoch nunmehr nicht mehr nur eine Randerscheinung, sondern wird im modernen Übersetzungsworkflow zunehmend in Zusammenarbeit von Mensch und Maschine eingesetzt. Fachübersetzer werden immer mehr zu Post-Editoren und korrigieren den MT/APE-Output, statt wie bisher Übersetzungen komplett neu anzufertigen. So kann die Produktivität bezüglich der Übersetzungsgeschwindigkeit gesteigert werden. Im letzten Jahrzehnt hat sich in den Bereichen Forschung und Entwicklung zur Verbesserung von MT sehr viel getan: Einbindung des vollständigen Übersetzungsworkflows von der Vorbereitung der Trainingsdaten über den eigentlichen MT-Prozess bis hin zu Post-Editing-Methoden. Der vollständige Übersetzungsworkflow wird jedoch aus Datenperspektive weit weniger berücksichtigt als der eigentliche MT-Prozess. In dieser Dissertation werden Wege hin zum idealen oder zumindest verbesserten MT-Workflow untersucht. In den Experimenten wird dabei besondere Aufmertsamfit auf die speziellen Belange von sprachen mit geringen ressourcen gelegt. Es wird untersucht wie unterschiedliche MT-Paradigmen verwendet und optimal integriert werden können. Des Weiteren wird dargestellt wie unterschiedliche vor- und nachgelagerte Technologiekomponenten angepasst werden können, um insgesamt einen besseren MT-Output zu generieren. Abschließend wird gezeigt wie der Mensch in den MT-Workflow intergriert werden kann. Das Ziel dieser Arbeit ist es verschiedene Technologiekomponenten in den MT-Workflow zu integrieren um so einen verbesserten Gesamtworkflow zu schaffen. Hierfür werden hauptsächlich Hybridisierungsansätze verwendet. In dieser Arbeit werden außerdem Möglichkeiten untersucht, Menschen effektiv als Post-Editoren einzubinden

DCU@FIRE-2014: fuzzy queries with rule-based normalization for mixed script information retrieval

We describe the participation of Dublin City University (DCU) in the FIRE-2014 transliteration search task (TST). The TST involves an ad-hoc search over a collection of Hindi film song lyrics. The Hindi language content of each document in the collection is either written in the native Devanagari script or transliterated in Roman script or a combination of both. The queries can be in mixed script as well. The task is challenging primarily because of the vocabulary mismatch which may arise due to the multiple transliteration alternatives. We attempt to address the vocabulary mismatch problem both during the indexing and retrieval stages. During indexing, we apply a rule-based normalization on some character sequences of the transliterated words in order to have a single representation in the index for the multiple transliteration alternatives. During the retrieval phase, we make use of prefix matched fuzzy query terms to account for the morphological variations of the transliterated words. The results show significant improvement over a standard baseline query likelihood language modelling (LM) approach. Additionally, we also apply statistical machine transliteration to train a transliteration model in order to predict the transliteration of out-of-vocabulary words. Surprisingly, even with satisfactory transliteration accuracy, we found that automatic transliteration of query terms degraded retrieval effectiveness