On Verifying Causal Consistency

Causal consistency is one of the most adopted consistency criteria for distributed implementations of data structures. It ensures that operations are executed at all sites according to their causal precedence. We address the issue of verifying automatically whether the executions of an implementation of a data structure are causally consistent. We consider two problems: (1) checking whether one single execution is causally consistent, which is relevant for developing testing and bug finding algorithms, and (2) verifying whether all the executions of an implementation are causally consistent. We show that the first problem is NP-complete. This holds even for the read-write memory abstraction, which is a building block of many modern distributed systems. Indeed, such systems often store data in key-value stores, which are instances of the read-write memory abstraction. Moreover, we prove that, surprisingly, the second problem is undecidable, and again this holds even for the read-write memory abstraction. However, we show that for the read-write memory abstraction, these negative results can be circumvented if the implementations are data independent, i.e., their behaviors do not depend on the data values that are written or read at each moment, which is a realistic assumption.Comment: extended version of POPL 201

Domain Generalisation with Bidirectional Encoder Representations from Vision Transformers

Domain generalisation involves pooling knowledge from source domain(s) into a single model that can generalise to unseen target domain(s). Recent research in domain generalisation has faced challenges when using deep learning models as they interact with data distributions which differ from those they are trained on. Here we perform domain generalisation on out-of-distribution (OOD) vision benchmarks using vision transformers. Initially we examine four vision transformer architectures namely ViT, LeViT, DeiT, and BEIT on out-of-distribution data. As the bidirectional encoder representation from image transformers (BEIT) architecture performs best, we use it in further experiments on three benchmarks PACS, Home-Office and DomainNet. Our results show significant improvements in validation and test accuracy and our implementation significantly overcomes gaps between within-distribution and OOD data.Comment: 4 pages, accepted at the Irish Machine Vision and Image Processing Conference (IMVIP), Galway, August 202

Exploring double skin façade as strategy for achieving thermal comfort in proposed mixed use office complex Kano, Nigeria

Thermal comfort can be defined as a state of mind which a human feels neither too hot nor too cold. Thermal discomfort in the case of hot humid climates, becomes a great threat to our livelihood and thermal comfort in offices in general. The ability of designers to harness and use the building envelope make life much better and livable is of great importance. This research seeks to use Double skin façade as a strategy for improving indoor thermal comfort by testing the air gap between the double skins. Climate and Weather readings were obtained and used to simulate and check the effect of Double skin façade in improving indoor thermal comfort in office complex. Double skin facade has been suggested by many researchers as a possible alternative technique for improving indoor thermal comfort. The double skin facade study in this research involved computer simulation using Emissions Control Optimization TEChnology (ECOTEC). The result of the final base case model shows that double skin façade can increase the indoor thermal comfort in a building and the wider the air gap, the higher the thermal comfort by showing the hours of comfort and discomfort to the simulated office building. The other important factor is that it can continuously induce the flow of natural ventilation, regardless of the available wind outside of the office complex building. This effect is significant toward improving the thermal comfort performance in the office complex through passive natural ventilation

Some Qur’anic Discourse Strategies in the Realization and Use of Terror vs.Horror: A Pragmalinguistic Study with Reference to the Translation Impacts

تبحث هذه الورقة البحثية في الاستراتيجيات اللغوية والسياقية المرتبطة بفهم واستخدام التعبيرين المتضادين "الإرهاب" و"الإرعاب" فيما يتعلق بمعانيهما المعجمية والإيحائية في خطاب القرآن المجيد والحديث الشريف. ولهذا الغرض، تم اختيار عدد من الآيات القرآنية  وبعض الأحاديث التي تحتوي على المصطلحين, وتم تحليل هذه العينات في ضوء الإطار النظري لمنهج سياقي- لغوي أستخدم كمنظور تحليلي لهذه الدراسة يستند في معظمه على نظرية عالم اللغة السياقي جيففير شيرين (1999), نظرية التكيف اللغوي (LAT). ومن خلال هذا المنهج,  تم وضع فرضية تنص على أن فهم واستخدام هذين المصطلحين في الخطاب الديني في القرآن والحديث يرتبط سياقيا باستراتيجيات لغوية وسياقية عديدة كامنة ذات دلالات معجمية وإيحائية مختلفة تتبلور من خلال التأثيرات والانطباعات الإدراكية الايجابية منها والسلبية على المتلقين للخطاب.وفي هذا السياق, يحاجي البحث بأن هذا الخطاب الديني يرتكز على عملية التكيف، القائمة على اتخاذ الاختيار والتفاوض الديناميكي الحيوي والتكيف اللغوي للمتغيرات الفيزيائية والاجتماعية والذهنية المتعلقة بسياق الموقف. ومن خلال هذا المنظور، يمكن تفسير وفهم هذا الخطاب من خلال استنباط وتكوين  المعنى  المستمد من نقاط التركيز الأربعة وهي: السياق والبناء الهيكلي والديناميكية والأهمية. وكشفت نتائج التحليل أن هذين المصطلحان يستخدمان بهدف  تحقيق استراتيجيات سياقية وأيديولوجية ترتكز في نوعها ومدلولاتها الخطابية على المعاني المعجمية والإيحائية المتضادة لهذين المصطلحين.لقد توصل البث إلى نتيجة مفادها أن هذين المصطلحين  يفهمان ويستخدمان بفعالية  وبقصد على أنهما  تعبيرين متضادين  في معانيهما اللفظية والإيحائية, وعلى أساس هذا الفهم والإدراك  يتم استخدامهما لغرض الوصول الى استراتيجيات سياقية محددة تجعل من النص الديني أداة وظيفية تضعها اللغة بيد المتحدثين والمتلقين لغرض تحقيق غاياتهم التواصلية بشكل أكثر ملائمة. وأخيرا, يأمل الباحثان بأن نتائج البحث فيما يتعلق بالمصطلحين اللغويين المتضادين "الإرهاب" و "الإرعاب" يمكن أن تكون ذو تأثير على قضايا ومجالات الترجمة, وخصوصا في العالم العربي.This paper investigates the communicative pragmatic strategies associated with the realization and use of the linguistic dichotomy"Terror" vs."Horror", with regard to their denotative and connotative meanings in the Glorious Quran (and Hadith) discourse. To that end, a number of Qur’anic verses and Hadith utterances containing the two terms have been chosen and analyzed within the theoretical framework of a pragmalinguistic approach as a perspective, mostly based on Jef Verschueren’s (1999) Linguistic Adaptation Theory (LAT).On the light of this model, it is argued here that the realization and use of these two terms in the religious discourse of Quran and Hadith indicate various underlying linguistic and pragmatic strategies with different denotations and connotations revealed from the positive and negative conceptualized impacts on interpreters. It is also argued that in the relevant  discourse, the adaptation process, based on choice making, dynamic negotiation, and linguistic adaptation to physical, social and cognitive variables of the context of situation, is used. From this perspective, such a discourse is interpreted with reference to the meaning generation derived from the focal points of context, structure, dynamics and salience. The results of the analysis reveal that these two terms are used for various different pragmatic (and ideological) strategies based on their contrasting denotations and connotations. The paper reaches a conclusion that these two linguistic expressions are dynamically and intentionally realized as two antonymous expressions with reference to their denotations and connotations, and used for certain  pragmatic strategies that make the religious discourse function as a tool provided by language for the utterers and interpreters to satisfy their communicative needs most appropriately. The results and conclusions, raised here, might be of significant effects, or impacts, on translation matters; particularly, in the Arabic world, insofar as the linguistic dichotomy "Terror" vs. "Horror" is concerned

Persistence of Small Noise and Random initial conditions

The effect of small noise in a smooth dynamical system is negligible on any finite time interval. Here we study situations when it persists on intervals increasing to infinity. Such asymptotic regime occurs when the system starts from initial condition, sufficiently close to an unstable fixed point. In this case, under appropriate scaling, the trajectory converges to solution of the unperturbed system, started from a certain {\em random} initial condition. In this paper we consider the case of one dimensional diffusions on the positive half line, which often arise as scaling limits in population dynamics

In vitro evaluation of fissure sealants’ wear under erosive, abrasive and erosive/abrasive conditions

Purpose To evaluate and compare the wear of selected resin-based fissure sealants with different compositions properties under erosive, abrasive, and erosive/abrasive conditions. Methods Forty-five samples of the following resin-based fissure sealants were prepared: Fissurit (fluoride free), Fissurit F (with fluoride), Fissurit FX (55 wt.% filler content), Grandio Seal (70 wt.% nano-filler content) and bovine enamel. Fifteen samples from each material were randomly allocated into three groups according to the wear condition they would be subjected to as follows: erosive condition (citric acid, 1 min, pH 2.3), abrasive condition (120 brushing strokes at 2 N, toothpaste slurry RDA value = 69), and erosive/abrasive condition (combination of both). The wear challenges were repeated six times each day for 10 days. The material wear was measured using a stylus profilometer. Kruskal–Wallis and Conover’s test was applied to compare the resulting material wear between the groups. Results Under erosive conditions, Grandio Seal and Fissurit FX showed statistically significantly the least material wear. Under abrasive and erosive/abrasive conditions, Grandio Seal showed statistically significantly the least material wear. Fissurit F showed statistically significantly the highest material wear under abrasive and erosive/abrasive conditions, after dental enamel (p < 0.05). Conclusion Higher filler content in sealants leads to better wear resistance. Incorporating fluoride into sealants seems to reduce their wear resistance at similar filler contents