bluuebunny/crossref_metadata_2025 huggingface dataset:
Directionally Solidified Ceramic Eutectics for High-Temperature Applications
Authors: Bogomol Iurii , Loboda Petro
Published: August 2013

The processing techniques, microstructures, and mechanical properties of directionally solidified eutectic ceramics are reviewed. It is considered the main methods for preparing of eutectic ceramics and the relationships between thermal gradient, growth rate, and microstructure parameters. Some principles of coupled eutectic growth, main types of eutectic microstructure and the relationship between the eutectic microstructure and the mechanical properties of directionally solidified eutectics at ambient and high temperatures are briefly described. The mechanical behavior and main toughening mechanisms of these materials in a wide temperature range are discussed. It is shown that the strength at high temperatures mainly depends on the plasticity of the phase components. By analyzing the dislocation structure, the occurrence of strain hardening in single crystalline phases during high-temperature deformation is revealed. The creep resistance of eutectic composites is superior to that of the sintered samples due to the absence of glassy phases at the interfaces, and the strain has to be accommodated by plastic deformation within the domains rather than by interfacial sliding. The microstructural and chemical stability of the directionally solidified eutectic ceramics at high temperatures are discussed. The aligned eutectic microstructures show limited phase coarsening up to the eutectic point and excellent chemical resistance. Directionally solidified eutectics, especially oxides, revealed an excellent oxidation resistance at elevated temperatures. It is shown sufficient potential of these materials for high-temperature applications.
Reactive Melt Infiltration of Carbon Fiber Reinforced Ceramic Composites for Ultra-High Temperature Applications
Authors: Shuxin Bai , Yonggang Tong , Yicong Ye , Hong Zhang
Published: August 2013

Carbon fiber reinforced ultra high temperature ceramic matrix composite (C/UHTC) is one of the most promising structural materials capable of prolonged operation in oxidizing environment at ultra high temperatures above 2000 ?C. Reactive melt infiltration (RMI) is a viable processing choice for C/UHTC composite. Compared with chemical vapor infiltration (CVI) and polymer impregnation and pyrolysis (PIP), RMI does not suffer from the drawbacks of time-consuming and high cost. It is viewed as a promising means of achieving near-net shape manufacturing with quick processing time and at low cost. Recently, great efforts have been made on RMI process for C/UHTC composite. Carbon fiber reinforced ZrC, HfC and TiC composites have been successfully fabricated by RMI. The aim of the following chapter is to introduce the RMI process and summarize the progress in RMI process for C/UHTC composite. In addition, future research directions of RMI are also proposed.
Fabrication, Microstructure, and Properties of Zirconium Diboride Matrix Ceramic
Authors: Wang Zhi , Wu Zhanjun
Published: August 2013

The crystal structure, synthesis, and densification of zirconium diboride (ZrB2) are summarized in detail. In this chapter, ZrB2-ZrC-SiC ceramic was synthesized by reactive hot pressing a mixture of Zr, B4C, and Si powders. The thermal shock resistance of the ZrB2-SiC-ZrC ceramic was estimated by the water-quenching method and was significantly greater than that of a ZrB2-15vol.% SiC ceramic. The isothermal oxidation of the ZrB2-SiC-ZrC ceramic was carried out in static air at constant temperatures of 1000±15, 1200±15, and 1400±15 ºC for different amounts of time at each temperature. The mechanism of strength increase for the oxidized specimen indicated that the strength increased with the reaction rate, which was related to the rate of change in volume induced by reaction, initial crack geometry, elastic modulus, and surface free energy. The formation of oxide layers resulted in (I) repair of surface flaws, (II) increase in flexural strength, (III) appearance of a compressive stress zone beneath the surface oxide layers, (IV) decrease in thermal stress, and (V) consumption of thermal stress. These five aspects were favorable to the improvement of the thermal shock resistance of the ZrB2-SiC-ZrC ceramic. The isothermal oxidation of the ZrB2-SiC-ZrC ceramic was carried out in static air at 1600±15 ºC. In the different oxidation stages, quantitative models were proposed for predicting oxidation kinetics.
C/C-ZrB2-ZrC-SiC Composites Derived from Polymeric Precursor Infiltration and Pyrolysis Part I
Authors: Zhang Weigang , Xie Changming , Ge Min , Wei Xi
Published: August 2013

Two-dimensional C/C-ZrB2-ZrC-SiC composites with three phases of ultra high temperature ceramics (UHTCs) are fabricated for the first time using blending pre-ceramic polymeric precursors through the traditional polymer infiltration and pyrolysis (PIP) technique, in which a porous carbon fiber reinforced pyrolytic carbon (C/C) with a porosity of about 60% is prepared as preforms. The fabricated composite possesses a matrix of 20ZrB2-30ZrC-50SiC, which is obtained by co-pyrolysis of three pre-ceramic polymers solution in xylene with certain molar ratios. Pyrolysis of these ZrB2-ZrC-SiC pre-ceramic precursors is studied with XRD characterization of the residual solids. The gas phase products are analysized with an on-line GC-MS-FTIR coupling technique, which confirms the formation of crystalline ZrC and ZrB2 from these precursors at temperatures above 1400°C. Possible mechanisms of pyrolysis and formation of pure ZrB2 from the precursors with various B/Zr molar ratios are suggested. The densification process and microstructures of the fabricated composite are studied. It is found that a composite with a bulk density of 2.06 g/cm3 and open porosity of 9.6% can be obtained after 16 PIP cycles. The formed matrix exhibits homogeneous dispersion of three matrix ceramics without any oxide impurities, i.e., the nano sized ZrB2 and ZrC particles dispersed in a continuous SiC ceramic with clean crystalline boundaries and particle dimensions less than 200 nm. No erosion or interface reaction occurs upon the carbon fiber reinforcement, which therefore avoids a dramatic deterioration of mechanical strength of carbon fiber and the composite. Improvement of PIP benefits from two aspects; firstly, the dense pyrolytic carbon interphase deposited on fiber surface by CVI serves as barrier coating and secondly, pyrolysis of the novel organic polymeric precursors does not release corrosive by-products such as hydrogen chloride.
Wetting and Joining of Structural Ceramic Components
Authors: Tian Wubian
Published: August 2013

This chapter summarises the recent studies on the wetting behaviors of ceramics which include carbides, oxides, nitrides, and borides at a wide temperature range and under various atmospheres. Also, their joining experiments, mainly by brazing and reaction joining methods, are reviewed. The typical and fundamental physical, mechanical, and microstructural examinations, such as contact angle, joint strength, and interlayer structure, are also presented.
Application of Electrophoretic Deposition for Interfacial Control of High-Performance SiC Fiber-Reinforced SiC Matrix (SiCf/SiC) Composites
Authors: Yoshida Katsumi
Published: August 2013

This chapter reviews the novel fabrication process of continuous SiCf/SiC composites based on electrophoretic deposition (EPD). EPD process is very effective for achieving relatively homogeneous carbon coating with the thickness of several tens to hundreds nanometers on SiC fibers. Carbon interface with the thickness of at least 100 nm formed by EPD acts effectively for inducing interfacial debonding and fiber pullout during fracture, and the SiCf/SiC composites show excellent mechanical properties. From these results, it is demonstrated that the fabrication process based on EPD method is expected to be an effective way to control the interfaces of SiCf/SiC composites and to obtain high-performance SiCf/SiC composites.
Phylogenetic Differential Evolution
Authors: Veloso de Melo Vinícius , Vargas Danilo Vasconcellos , Crocomo Marcio Kassouf
Published: August 2013

This paper presents a new technique for optimizing binary problems with building blocks. The authors have developed a different approach to existing Estimation of Distribution Algorithms (EDAs). Our technique, called Phylogenetic Differential Evolution (PhyDE), combines the Phylogenetic Algorithm and the Differential Evolution Algorithm. The first one is employed to identify the building blocks and to generate metavariables. The second one is used to find the best instance of each metavariable. In contrast to existing EDAs that identify the related variables at each iteration, the presented technique finds the related variables only once at the beginning of the algorithm, and not through the generations. This paper shows that the proposed technique is more efficient than the well known EDA called Extended Compact Genetic Algorithm (ECGA), especially for large-scale systems which are commonly found in real world problems.
Asynchronous P Systems
Authors: Bălănescu Tudor , Nicolescu Radu , Wu Huiling
Published: August 2013

In this paper, the authors propose a new approach to fully asynchronous P systems, and a matching complexity measure, both inspired from the field of distributed algorithms. The authors validate the proposed approach by implementing several well-known distributed depth-first search (DFS) and breadth-first search (BFS) algorithms. Empirical results show that the proposed P algorithms have shorter descriptions and achieve a performance comparable to the corresponding distributed algorithms.
P Colonies of Capacity One and Modularity
Authors: Cienciala Luděk , Ciencialová Lucie , Langer Miroslav
Published: August 2013

In this paper, the authors continue the investigation of P colonies introduced in Kelemen, Kelemenová, and Paun (2004). This paper examines a class of abstract computing devices composed of independent agents, acting and evolving in a shared environment. The first part is devoted to the P colonies of the capacity one. The authors present improved results concerning the computational power of the P colonies with capacity one and without using checking programs. The second part of the paper examines the modularity of the P colonies. The authors then divide the agents into modules.
Forward and Backward Chaining with P Systems
Authors: Ivanov Sergiu , Alhazov Artiom , Rogojin Vladimir , Gutiérrez-Naranjo Miguel A.
Published: August 2013

One of the concepts that lie at the basis of membrane computing is the multiset rewriting rule. On the other hand, the paradigm of rules is profusely used in computer science for representing and dealing with knowledge. Therefore, establishing a “bridge” between these domains is important, for instance, by designing P systems reproducing the modus ponens-based forward and backward chaining that can be used as tools for reasoning in propositional logic. In this paper, the authors show how powerful and intuitive the formalism of membrane computing is and how it can be used to represent concepts and notions from unrelated areas.
The Grand Challenges in Natural Computing Research
Authors: Nunes de Castro Leandro , Xavier Rafael Silveira , Pasti Rodrigo , Maia Renato Dourado , Szabo Alexandre , Ferrari Daniel Gomes
Published: August 2013

An important premise of Natural Computing is that some form of computation goes on in Nature, and that computing capability has to be understood, modeled, abstracted, and used for different objectives and in different contexts. Therefore, it is necessary to propose a new language capable of describing and allowing the comprehension of natural systems as a union of computing phenomena, bringing an information processing perspective to Nature. To develop this new language and convert Natural Computing into a new science it is imperative to overcome three specific Grand Challenges in Natural Computing Research: Transforming Natural Computing into a Transdisciplinary Discipline, Unveiling and Harnessing Information Processing in Natural Systems, Engineering Natural Computing Systems.
Knowledge Management Initiatives in Indian Public Sector
Authors: Baporikar Neeta
Published: August 2013

Today, knowledge management has come to be accepted and recognized as a source of competitive advantage in the private sector. Although Knowledge Management (KM) has been gaining attention all over the world, KM as a discipline is still in its infancy, and adoption of KM is still at its nascent stage when it comes to the Public Sector. It is vital for any organization to understand the concept of KM so as to align its KM strategy with the organization’s strategy. This is all the more important when it is the Public Sector because the impact of Public Sector organizations directly affects the common man. Knowledge creation, generation, and application are a continuous process. Without thorough understanding and awareness of KM, the Public Sector may not be able to reap true and full benefits. This chapter aims to bring a comprehensive understanding of KM application to the Public Sector and through cases recognizes the initiatives of KM in the Indian Public Sector.
Government as a Partner in Knowledge Management
Authors: Erickson G. Scott
Published: August 2013

This chapter assesses the reliability and predictability of government departments as partners in corporate knowledge management systems. The specific topic is knowledge availability under the US Freedom of Information Act, but the general implications apply to governments at all levels around the world that hold business information, data, or knowledge assets. By comparing processes related to US freedom of information requests across departments and across time, separated by a dramatic change in presidential administrations and attitudes toward governmental openness, this study examines the relative reliability of agency processes. In particular, reports on the handling of confidential business information provide us with specific insights on this topic as do reports on records with personal privacy concerns. In the end, there appears to be little predictability in the process, even with clear instruction from the highest levels. The topic needs more in-depth study, but businesses, at least in the US, should share data, information, and knowledge with the government deliberatively.
Organisational Readiness for Knowledge Management
Authors: Shajera Amani , Al-Bastaki Yousif
Published: August 2013

This study explores the factors that affect organisational readiness for Knowledge Management (KM). This chapter assesses the organisational readiness for KM at public sector organisations in Bahrain; furthermore, it utilises these findings to develop a guideline to enable the successful adoption and implementation of KM. A questionnaire survey was conducted at the public sector organisations in Bahrain. The research findings indicate that culture (collaboration, trust, and learning), structure (centralisation, formalization, and rewards systems), and IT infrastructure (IT support) all provide a sound basis for organisations to assess their readiness for KM. The results show that the public sector organisations in Bahrain vary in terms of readiness levels against the different variables. The findings are discussed and relevant recommendations are made with regards to KM adoption at the public sector organisations in Bahrain. The findings imply a need for intensified organisational and managerial commitment in order to promote collaboration, trust, learning, decentralisation, less formalisation, reward systems, and enhanced IT support at the public sector organisations in Bahrain. Implementation of these required changes in the public sector’s culture and structure will help in preparing the public sector and their awareness and readiness to implement KM. This study is among the first empirical works assessing organisational readiness for adopting KM. Moreover, this chapter has extended knowledge in KM, especially concerning the need for the consideration of organisational readiness before embracing KM. The most significant contribution of this chapter is that it provides an instrument for assessing organisational readiness. It serves as a guideline for leaders and helps them to ensure that essential preliminary factors and variables are promoted and covered when they start KM implementation within their organisations.
Drivers, Benefits, and Challenges of Knowledge Management in Electronic Government
Authors: Salleh Kalsom
Published: August 2013

This chapter explores the role of Knowledge Management (KM) and knowledge workers in the public sector organization in the broader perspective towards achieving the Electronic Government orientation in Malaysia. The future implementation of KM in the public sector organizations should leverage and articulate the experiences, ideas, and expertise of an organization’s knowledge workers for the embedded organizational knowledge. A survey questionnaire was used to collect data from all public sector accountants working in the accounting specialist department of the Federal Government in Malaysia. This selected knowledge intensive accounting organization has a large pool of public sector accountants and the core competencies of the organization are to provide timely accounting information and quality accounting services to all agencies of the Federal Government. Public sector accountants (knowledge workers) are responsible for the strategic policies and operational management in various departments of this selected public sector organization. The responses from the questionnaires are aimed to preliminarily examine the organizational readiness in technology resources as well as to identify the perceived benefits and challenges in using KM as a strategic management tool to improve the internal operational efficiency and electronic service delivery system for E-Government in this selected knowledge intensive accounting organization in Malaysia.
Enabling Factors for Knowledge Sharing among Employees in the Workplace
Authors: Assefa Temtim , Garfield Monica , Meshesha Million
Published: August 2013

This chapter investigates enabling factors that promote knowledge sharing among employees in the workplace. The study was conducted on employees of Commercial Bank of Ethiopia (CBE) as a research case. Banks in particular and financial institutions in general are now becoming knowledge intensive organizations where knowledge is used as a key strategic resource to achieve their business goals as well as competitive advantage. This study uses an exploratory case study research method that allows deeper understanding and interpretation. Although there is plenty of literature on knowledge sharing, existing findings are not consistent due to the influence of contextual factors on knowledge sharing. This study identifies organizational, individual, task characteristics, and technological factors as main enabling factors that promote knowledge sharing in the workplace. Although organizations put much emphasis on technology to promote knowledge sharing in the workplace, non-technological factors (organizational and individual factors) appear more significant. As the study was conducted on a commercial bank within developing economies context, it contributes additional perspectives to confirm or extend existing findings on knowledge sharing.
Education in Egypt and its Role in the Global Community
Authors: Ahmed Azzam Abd-El Naby , Witte Maria Martinez , Witte James E.
Published: August 2013

The Egyptian revolution of January 2011 has brought about tremendous changes within Egypt’s political and social institutions. This chapter examines historical and current events that have shaped educational reform and practices. Educational policies have been heavily influenced by external agencies. International organizations have targeted educational programming and infrastructure resulting in educational transfer practices focused on global topics. Issues surrounding post-revolution educational changes are addressed as well as the role of globalization processes.
An Investigation of the Relationship of Motivation, Attitudes and Environment
Authors: Yeh Wai Man Helen,
Published: August 2013

This chapter will study a Philippine and a Chinese leaner’s approaches to learn and achieve English language proficiency over 15 years in Hong Kong using biographical approaches. It focuses on the experience of individual motivation and social learning environments, and examines the interactions between the learner’s motivation, self-confidence, and competition in the global economy. The effect of the interaction on shaping English learning and the learning experiences in three aspects including formal, self-directed and natural learning environments will also be discussed through Gardner’s model of socio-educational model in second language acquisition and Weiner’s attribution theory in social psychology. The chapter will suggest some practical implications for students and language teachers, discusses the ways to enhance second language learning in a cosmopolitan city, and presents some possible ways to increase learners’ motivation and competitiveness in the global economy.
Open, Flexible and Participatory Pedagogy in the Era of Globalisation
Authors: McLoughlin Catherine
Published: August 2013

The socio-political and economic conditions of the world signal that the global society is moving towards an era of international, cross-border collaboration in education. International higher education by its very nature sits at an intersection of socio-cultural, economic, and geopolitical variables. Over the years, we have seen the complex interaction of the factors that influence patterns of student mobility, institutional strategies and economic forces. Worldwide, institutions of higher education (IHEs) are including global and international themes in their mission statements, courses, and strategic plans. Internationalization is seen as the integration of an international/intercultural dimension into teaching, research, and service of an institution. Internationalizing educational delivery can require significant change and is systematically complex, requiring faculty, staff, students, administrators, and community members who aspire to communicate with, understand, and connect with the diverse 21st-century global community. In this globally connected millennium, as institutions are moving towards Open Access and the use of OER (Open Education Resources) to widen participation and access to higher education, there is a consequent need to redesign pedagogy, teacher roles, and the use of technology to support learning.
Impact of National Culture on Business Continuity Management System Implementation
Authors: Shukla Praval , Kumar Abhijeet , Anu Kumar P.B.
Published: August 2013

It is increasingly evident that the concerns of business continuity management are not limited by national boundaries. Yet, very few studies have been carried out on business continuity from a cross-cultural perspective. The current paper tries to address this gap in literature by looking at a Business Continuity Management System (BCMS) implementation. The researchers examine the impact of national culture on the variables of BCMS implementation success using Hofstede’s cultural dimensions as factors. The unique aspect this study was that the researchers analyzed BCMS implementation effectiveness through the four phases of the PDCA cycle, while assessing the impact of Hofstede’s cultural dimensions.
Proposed Isomorphic Graph Model for Risk Assessment on a Unix Operating System
Authors: Patra Prashant Kumar , Pradhan Padma Lochan
Published: August 2013

Control and risk are the two parts of the coin. Risk assessment is the process of identifying uncertainties, vulnerabilities and threats to the operating system resources in order to achieve business objectives. Risk evaluation involved deciding what counter measures to take in reducing uncertainty to the lowest level of risk. Control is probably the most important aspect of communications security and becoming increasingly important as basic building block for system security. Advanced Encryption Standard (AES) is a primary method of protecting system resources. AES is inversely proportional to the Risk (C=K/R) & mean while control is directly proportional to the quality of standard. AES Control will be optimize the risk as well as improve the IS standard. Control is directly proportional to risk mitigation & mitigation is directly proportional to standard. This paper contributes to the development of an optimization method that aims to determine the optimal cost to be invested into security method, model & mechanisms deciding on the measure component of operating system resources (i.e. Processor, Memory & Encryption). Furthermore, the method & mechanism optimize the cost, time & resources is supposed to optimize the system risks. The proposed model would be update the value of Processor, Memory & Encryption key dynamically as per business requirement and availability of technology & resources. Proposed model is going to be optimizing risk and maximizing the performance. In this study the researchers develop an isomorphic graph model for optimizing risk in the Unix operating system.
Two Rare Hemoglobin Variants with α Thalassemia in Eastern Indian Population
Authors: Das Dipanwita , Chattopadhyay Nandini , Mukherjee Arghya , Chattopadhyay Dhrubajyoti , Chakrabarti Prantar , Chaudhuri Utpal , Chakrabarti Sila
Published: August 2013

The current work focuses on two rare hemoglobin (Hb) variants - Hb Grange-Blanche and Hb Hofu - found for the first time in association with α-thalassemia in Eastern India. The unusual case of Hb Grange-Blanche and FS 41/42(-CTTT) mutations in cis throws light on importance of multiple mutations and its coinheritance with αααanti3.7 triplication indicates a possible cause for the clinical severity in β-thalassemia carriers.
Creation of a contusion injury in rabbit skeletal muscle using a drop-mass technique
Authors: Deane Margaret N. , Gregory Michael , Mars Maurice , Bester Linda
Published: August 2013

This study reports our experience in developing a simple, minor injury. After reviewing the literature, a ‘drop-mass’ method was selected where a 201 g, elongated oval-shaped weight was dropped up to 15 times through a 1 m tube onto the left vastus lateralis of New Zealand white rabbits. To determine the extent of injury and degree of healing, biopsies were obtained six days after injury from the healing vastus lateralis of each animal. The tissue was fixed in formal saline, embedded in wax, cut and stained with haematoxylin and eosin (HE) and phosphotungstic acid haematoxylin (PTAH) and examined by light microscopy (LM). The ‘optimal’ injury was created after seven drops, where quite severe, mild and moderately severe trauma was caused to muscle in the juxta-bone, mid and sub-dermal regions respectively. In each region, the muscle exhibited features of healing six days after injury. The ‘drop-mass’ technique appears to cause a contusion within a single muscle of at least three degrees of severity. This previously unreported observation is of particular importance to other researchers wishing to investigate contusion injury in other animal models.
Long-term stability of grazing lawns in a small protected area, the Mountain Zebra National Park
Authors: Novellie Peter , Gaylard Angela
Published: August 2013

We examined a heavily grazed plant community dominated by creeping grass species with the aim of, (1) determining its response to the exclusion of grazing and (2) its long-term persistence. This plant community was particularly favoured by wild ungulate species that prefer short grasses – blesbok (Damaliscus dorcas phillipsi), springbok (Antidorcas marsupialis) and black wildebeest (Connochaetes gnou). Exclusion of grazing by large herbivores by means of fencing resulted in the virtual disappearance of the creeping grasses and their replacement by tall tufted species. On plots that remained unfenced, the plant species composition was found to be little changed after an interval of more than 20 years. The number large stock unit equivalents (LSU) per ha carried by the plant community was used as a proxy for grazing intensity. Monitored for approximately 2 years at the start of the study, LSU per ha was found to greatly exceed levels recommended for commercial livestock production. This plant community conforms to a recently published definition of a grazing lawn, in that intense grazing promotes palatable, grazing-tolerant grass species.Conservation implications: The positive association between grazers and grazing-tolerant grass species evidently persisted for more than 20 years and there was no evidence of an increase in abundance of unpalatable plant species. Despite the small size of the park, which limited the extent of large herbivore movements, localised heavy grazing did not lead to range degradation.
Cerebrotendinous Xanthomatosis: Report of two cases and a novel genetic mutation in an Indian patient
Authors: Bajaj Bhupender K. , Singh Anand , Anand Kuljeet S. , Garg Jyoti
Published: August 2013

Cerebrotendinous Xanthomatosis (CTX) is an autosomal recessive disorder of bile acid metabolism manifesting typically with the triad of neurological dysfunction, tendon xanthoma, and early onset cataract. The diagnosis is often missed and delayed as the patients do not manifest all the classical features. Early recognition and initiation of chenodeoxycholic acid therapy with Hydoxymethylglutaryl Coenzyme‑A (HMG‑Co‑A) inhibitors is critical to prevent irreversible neurological damage and permanently disabled existence. We report about two patients, both of whom remained undiagnosed for more than 20 years. Genetic analysis in one of the patients revealed a novel genetic mutation in one of the homologous genes. The patient was found to have heterozygous mutation of CTX gene with a novel mutation in exon 1 of CYP27A1 gene.
REM sleep behavior disorder in Parkinson’s disease: A case from India confirmed with polysomnographic data
Authors: Gupta Ravi , Goel Deepak , Walker Jim , Farney Robert J.
Published: August 2013

Rapid eye movement (REM) sleep behavior disorder is a condition characterized by dream enactment. This condition may accompany neurodegenerative disorders. However, only a few reports from India are available, that too, without any polysomnographic evidence. We are reporting a case of REM sleep behavior disorder with polysomnographic evidence.
Extracranially located PICA aneurysm presenting with supratentorial IVH: A rare event with diagnostic pitfalls
Authors: Savardekar Amey , Tewari Manoj Kumar , Garg Rajeev , Gupta Vivek , Ahuja Chirag
Published: August 2013

Extracranially located posterior inferior cerebellar artery (PICA) aneurysms are rare with only 21 cases reported till date. They may arise either from the proximal segment of an extracranially originating PICA or from the tip of its caudal loop when it dips below the foramen magnum. A 16-year-old female presenting with sudden onset severe headache and intraventricular hemorrhage (IVH) in the occipital horns of the lateral ventricle and the fourth ventricles, was diagnosed to have an extracranial proximal segment PICA aneurysm on a four vessel digital subtraction angiography (DSA), after initially missing it on the brain magnetic resonance imaging (MRI) with angiogram (MRA) because of its extracranial location. During surgery, the aneurysm was clipped following a far lateral suboccipital craniectomy with C1‑C2 hemilaminectomy. The patient showed good recovery. Thus, we emphasize the need for a dedicated four vessel angiography to diagnose such lesions.
Self-limiting symptomatic peri-ictal bradyarryhthmia due to junctional AV rhythm
Authors: Babarao Hanmantrao Darku , Madhu Nagappa , Sinha Sanjib , Prasad Chandrajit , Somasekhar Nagaraju
Published: August 2013

We report an elderly man with chronic uncontrolled localization.related epilepsy on three AEDs, who developed in.hospital symptomatic bradyarrythmia due to junctional atrio-ventricular (AV) rhythm after an episode of generalized seizure during his hospital stay. On further evaluation, the cardiac enzymes were normal and 2D.echocardiogram showed mild left ventricular hypertrophy. Patient recovered from the same with supportive treatment within few hours. We emphasize on importance of prompt recognition of this event and its implication including one of the mechanism for sudden unexplained death in epilepsy.
Occult spontaneous lateral intrasphenoidal encephalocele: A rare presentation
Authors: Bano Shahina , Chaudhary Vikas , Yadav Sachchida N , Garga Umesh C
Published: August 2013

Basal encephaloceles are extremely rare congenital malformations. Advanced cross-sectional imaging modalities like computed tomography and magnetic resonance imaging are necessary for diagnosing the asymptomatic, occult basal encephalocele and planning the surgical approach. We present an interesting case of clinically silent right-sided lateral intrasphenoidal encephalocele through a large bony defect.
Isolated cysticercosis of the cauda equina
Authors: Iacoangeli Maurizio , Moriconi Elisa , Gladi Maurizio , Scerrati Massimo
Published: August 2013

Cysticercosis is the most common parasitic infection of the central nervous system. It is an endemic condition in developing countries, but the incidence rate is increasing in developed countries as well because of rising immigration. Spinal involvement is quite rare and it is usually associated with concomitant intracranial infective lesions. We present an unusual case of a 44-year-old woman who experienced a cauda equina syndrome. Magnetic resonance imaging disclosed two intradural cystic lesions at L4-L5 level. Only after histological examination the diagnosis of cysticercosis was definitively determined. The entire neuraxis evaluation confirmed that it was a rare form of isolated intradural racemosus type cysticercosis of the cauda equina. Steroids and albendazole were administered and post-operative course was uneventful. In this paper we discuss clinical, pathogenic and therapeutic aspects of this infective pathology.
Intra cranial hydatid cyst: A case report of total cyst extirpation and review of surgical technique
Authors: Umerani Muhammad Sohail , Abbas Asad , Sharif Salman
Published: August 2013

Hydatid cysts commonly affect liver and lung but it can also affect the brain in rare cases. We report a case of 22 year female with history of headache for one and half years. Intracranial hydatid cyst was diagnosed on computed tomography scan and magnetic resonance imaging. The cyst was delivered without rupture using hydrostatic dissection followed by post‑operative anthelminthic medication. Surgery remains to be the standard management. Amongst the surgical techniques described, Dowling’s technique is the most acceptable. However, care must be taken in to avoid rupture of the cyst peroperatively which can result in subsequent complications and recurrence. Albendazole and corticosteroids can be used as adjunct to surgical treatment in selective cases.
Hydra groups
Authors: Dison Will , Riley Timothy R.
Published: August 2013

We give examples of CAT(0), biautomatic, free-by-cyclic, one-relator groups which have finite-rank free subgroups of huge (Ackermannian) distortion. This leads to elementary examples of groups whose Dehn functions are similarly extravagant. This behaviour originates in manifestations of
Hercules-versus-the-hydra battles
in string-rewriting.
Un critère d’indépendance pour une famille de représentations $\ell$-adiques
Authors: Serre Jean-Pierre
Published: August 2013

We give a criterion for the independence of a family of

\ell

-adic Galois representations of a number field.
Finite groups of essential dimension 2
Authors: Duncan Alexander
Published: August 2013

We classify all finite groups of essential dimension 2 over an algebraically closed field of characteristic 0.
The classification of universal Jacobians over the moduli space of curves
Authors: Farkas Gavril , Verra Alessandro
Published: August 2013

We complete the classification by Kodaira dimension of the moduli space of degree

g

line bundles over curves of genus

g

, for all genera.
Rigidity of pseudo-Anosov flows transverse to $\mathbb{R}$-covered foliations
Authors: Fenley Sérgio R.
Published: August 2013

A foliation is

\mathbb{R}

-covered if the leaf space of the lifted foliation to the universal cover is homeomorphic to the set of real numbers. We show that, up to topological conjugacy, there are at most two pseudo-Anosov flows transverse to a fixed

\mathbb{R}

-covered foliation. If there are two transverse pseudo-Anosov flows, then the foliation is weakly conjugate to the stable foliation of an

\mathbb{R}

-covered Anosov flow. The proof uses the universal circle for

\mathbb{R}

-covered foliations.
Varieties $n$-covered by curves of degree $\delta$
Authors: Pirio Luc , Russo Francesco
Published: August 2013

We continue the study, began by classical geometers and considered more recently in [33] and [52], of complex projective varieties

X\subset\mathbb P^N

such that through

n\geq 2

general points of

X

there passes an irreducible curve of degree

\delta

.
Geometry of orbits of permanents and determinants
Authors: Kumar Shrawan
Published: August 2013

We prove that the orbit closure of the determinant is not normal. A similar result is obtained for the padded permanent (i.e., the permanent multiplied by a power of a linear form).
Predictive Factors of HTLV1-HIV Coinfections in French Guiana
Authors: Gouhier Elise , Gaubert-Maréchal Emilie , Abboud Philippe , Couppié Pierre , Nacher Mathieu
Published: August 2013

French Guiana, the French territory most affected by human immunodeficiency virus (HIV) (1.3% of pregnant women), is also endemic for human T lymphotropic virus 1 (HTLV1). The objective of this study was to determine if the HTLV1/HIV coinfected patients had particular characteristics. All HIV-infected patients having a computerized medical file containing an HTLV1 serology were included: there were 1,333 HIV monoinfections and 76 HTLV1/VIH coinfections. The prevalence of HTLV1/HIV coinfections was 5.39%. Women (odds ratio [OR] = 1.91[1.13–3.24]), subjects > 40 years of age, and patients of Surinamese origin (OR = 2.65 [1.25–5.61]) were overrepresented among the coinfected. CD4 count at the time of diagnosis and viral loads were higher among coinfected patients. The clinical stage was not significantly different between the two groups. The number of CD4 cells was not higher among the coinfected, unlike most reports from the literature. Prevalence of HTLV1 among HIV-infected patients is high in French Guiana, and physicians seem to omit the prescription of serology for this potentially serious coinfection.
Eat for Life: A Work Site Feasibility Study of a Novel Mindfulness-Based Intuitive Eating Intervention
Authors: Bush Hannah E. , Rossy Lynn , Mintz Laurie B. , Schopp Laura
Published: August 2013

Purpose.

To examine the efficacy of a novel intervention for problematic eating behaviors and body dissatisfaction.

Design.

Participants enrolled in the intervention or waitlist comparison group were assessed at pre and post 10 weeks.

Setting.

Midwestern university.

Subjects.

One hundred twenty-four female employees or partners/spouses.

Intervention.

Eat for Life is a 10-week group intervention integrating mindfulness and intuitive eating skills.

Measures.

Self-report questionnaires included the Intuitive Eating Scale, Body Appreciation Scale, Five-Facet Mindfulness Questionnaire, Questionnaire for Eating Disorder Diagnoses, and an author-constructed supplemental and demographic questionnaire.

Analysis.

Analyses of covariance and ordinal regression measured group differences. Structural equation modeling examined mediation effects.

Results.

Significant differences between groups were observed for body appreciation (F1,121 = 40.17, p=.000, partial eta squared=.25), intuitive eating (F1,121=67.44, p=.000, partial eta squared = .36), and mindfulness (F1,121 = 30.50, p = .000, partial eta squared = .20), with mean scores significantly higher in the intervention group than waitlist comparison group after 10 weeks. The intervention group was 3.65 times more likely to be asymptomatic for disordered eating than the comparison group. Mindfulness served as a partial mediator.

Conclusion.

The study provides support for an intervention combining intuitive eating and mindfulness for treatment of problematic eating behaviors and body dissatisfaction, with limitations including self-selection and lack of active control group.
Impact of Promotions on Awareness, Trial, and Likelihood of Trial of New Dissolvable Tobacco
Authors: Romito Laura , Saxton M. Kim
Published: August 2013

Purpose.

To determine test market awareness and promotional effects of Camel dissolvable tobacco.

Design.

Cross-sectional survey.

Setting.

Indiana test market.

Subjects.

Stratified sample of Indiana adults (N = 472).

Measures.

Data were poststratified and weighted to account for the sampling and demographics.

Analysis.

Descriptive statistics and multivariate analysis.

Results.

The study results indicate that 31.2% of participants were aware of Camel Dissolvables, 4.5% had tried them, and 8.3% were likely to try them. Tobacco use was a significant predictor of all outcomes; dual (cigarettes and smokeless tobacco) users were more likely to be familiar with, try, and be interested in trying Camel Dissolvables than single tobacco users and nonusers (p < .05). Male gender was a significant predictor only for likelihood of trial (p < .05). Education was a significant predictor only of actual trial (p < .05). Familiarity was predicted by in-store, magazine, and mail promotions. Trial was predicted by having seen magazine ads. Web site exposure predicted likelihood of trial. Of those who reported trying Camel Dissolvables (N = 37), 49% no longer used them, 43% used them some days, and 8% used them daily. Continued use was reported by 87% of dual users and 26% of single tobacco users (p < .01).

Conclusion.

Smokers and male dual tobacco users appear most affected by Camel Dissolvables promotions.
Psychosocial Predictors of Diet and Physical Activity in African-Americans: Results from the Delta Body and Soul Effectiveness Trial, 2010–2011
Authors: Thomson Jessica L. , Zoellner Jamie M. , Tussing-Humphreys Lisa M.
Published: August 2013

Purpose.

To examine associations among psychosocial constructs of behavior change and postintervention changes in diet and physical activity (PA).

Design.

Quasi-experimental with cluster (church) treatment assignment.

Setting.

Churches (n = 8) in a rural, southern region of the United States.

Subjects.

A total of 403 African-American adults participating in the Delta Body and Soul study.

Intervention.

Six-month diet and PA intervention consisting of monthly didactic educational sessions with specific emphasis on increasing consumption of fruits, vegetables, and whole grains, and decreasing consumption of added sugars. Self-directed PA was promoted throughout the intervention.

Measures.

Validated surveys for all dietary, PA, and psychosocial measures.

Analysis.

Secondary analysis using generalized linear mixed models to test for significant intervention effects on psychosocial constructs and for significant associations between changes in psychosocial constructs and changes in diet and PA outcomes after controlling for covariates.

Results.

Intervention effects were apparent for several dietary psychosocial constructs (improvements ranging from .5 to 2.0 points), but only one PA construct (decisional balance for exercise). Changes in psychosocial constructs, including self-efficacy, social support, and decisional balance, were significant predictors of dietary outcome changes (model coefficients ranging from .03 to .42), but not PA changes.

Conclusion.

Understanding which psychosocial constructs predict improvements in dietary and PA behaviors helps inform theoretical mechanisms of action and identify social and behavioral processes to target in faith-based interventions.
Scales of Smoking-Related Self-Efficacy, Beliefs, and Intention: Assessing Measurement Invariance among Intermittent and Daily High School Smokers
Authors: Sterling Kymberle L. , Ford Kentya H. , Park Haesuk , McAlister Alfred L.
Published: August 2013

Purpose.

To examine the factorial validity and measurement invariance of scales that measure smoking-related self-efficacy, beliefs, and intention between daily and intermittent adolescent smokers.

Design.

Cross-sectional survey design.

Setting.

Selected high schools in eastern Texas.

Subjects.

Subjects were 2888 high school current smokers; mean age 16.2 years; 53.5% male; 67.4% White, 17.8% Hispanic, 6.2% Black, 8.6% “other.” Daily smokers comprised 37.9% of the sample (i.e., smoked at least one cigarette every day 30 days prior to the survey).

Measures.

Smoking-related self-efficacy and intention were measured by three items; beliefs were measured by four items.

Analysis.

Confirmatory factor analyses were conducted to test the invariance of the measures between daily and intermittent smokers. Fit indices included comparative fit index (CFI), nonnormed fix index (NNFI), and root mean square error of approximation (RMSEA).

Results.

The three-factor measurement model had good fit for daily (CFI = .97, NNFI = .95, RMSEA = .09) and intermittent (CFI = .96, NNFI = .95, RMSEA = .09) smokers. Evidence of strong factorial invariance was found for the factors between the smoking subgroups (CFI = .96, NNFI = .96, RMSEA = .08).

Conclusion.

These measures may be used to capture and compare scores on self-efficacy to resist smoking, beliefs about benefits of smoking, and intention to smoke between daily and intermittent adolescent smokers.
Physiological and Psychological Effects of a Himalayan Singing Bowl in Meditation Practice: A Quantitative Analysis
Authors: Landry Jayan Marie
Published: August 2013

Purpose.

To determine the physiological and psychological effects of adding a Himalayan singing bowl (HSB) to a directed relaxation (DR) session.

Design.

Randomized crossover study.

Setting.

Community-based counseling practice.

Subjects.

Fifty-one participants completed two randomly assigned sessions beginning with either 12 minutes of HSB or silence, followed by a 20-minute DR session.

Intervention.

Random order of HSB intervention/silence prior to DR.

Measures.

Blood pressure (BP), heart rate (HR), Positive and Negative Affect Schedule (PANAS) scores measured before and after both sessions.

Analysis.

Analysis of variance (ANOVA) compared differences between variables over time between both study days, and analysis of covariance (ANCOVA) analyzed changes from baseline, controlling for baseline, age, and sex.

Results.

Fifty-one participants completed both sessions. There was a greater decline in systolic BP (p = .044) and HR (p = .003) with HSB compared to silence prior to DR. Changes in diastolic BP were greater with HSB, with a nonsignificant trend (p = .073). Hypertensive subjects (n = 20) had similar and significant BP changes with HSB and silence when compared to normotensive subjects (n = 31). PANAS scores fell significantly with both interventions.

Conclusions.

BP and HR responses were enhanced by HSB exposure. HSB may be used as an adjunct to DR to produce physiological and psychological responses prior to DR.