bluuebunny/crossref_metadata_2025 huggingface dataset:
School, family and other influences on assistive technology use
Authors: Meng Ee Wong  , Cohen Libby
Published: May 2011

Assistive technologies are essential enablers for individuals with visual impairments, but although Singapore is technologically advanced, students with visual impairments are not yet full participants in this technological society. This study investigates the barriers and challenges to the use of assistive technologies by students with visual impairments in Singapore in a special school context. Findings reveal limited content knowledge amongst teachers in assistive technology resulting in inconsistencies and inadequacies in the delivery of instruction. Students also display a mixed range of abilities ranging from little to basic knowledge. Where formal channels fail to impart knowledge, family and external influences are found to feature as potentially important contributors to skill acquisition in assistive technology and access. The evidence highlights an urgent need to equip teachers with training in assistive technology and to strengthen collaboration between school and stakeholders.
Jim Crow’s Daughters Different Social Class-Different Experience With Racism
Authors: Carter-Black Janet D. , Kayama Misa
Published: May 2011

African American women share the common ground of surviving in a racially stratified society. Nonetheless, the diversity of their experiences emerges. This article contrasts the lived experiences of two elderly African American daughters of the Jim Crow South. Commonly shared social markers (race, gender, and historical and regional contexts) are held in contrast to their notably different social classes. Salient features of their diverse experiences corroborate the supposition that although all African American women encounter racism, social-class differences influence how racism is experienced. Family racial socialization pathways are conceptualized as reliance on personal resources versus reliance on personal defiance.
Experiences of Muslims in Four Western Countries Post—9/11
Authors: Barkdull Carenlee , Khaja Khadija , Queiro-Tajalli Irene , Swart Amy , Cunningham Dianne , Dennis Sheila
Published: May 2011

This qualitative study explored the experiences of 34 Muslim individuals in four Western countries to gain a better understanding of their experiences with prejudice and discrimination following the terrorist attacks of September 11, 2001. An intersectional lens reveals the interlocking nature of identity, oppression, and privilege, and the findings provide insights into what helps affected individuals and communities be resilient in the face of persistent anti-Muslim sentiment. The social work profession is called on to take a leadership role in addressing the stigmatization of Muslims as a social justice issue and to take action to ameliorate its causes and consequences.
The Social Control of Family Violence
Authors: Messing Jill Theresa
Published: May 2011

There has been a decidedly different social response to the abuse of a child and the abuse of an intimate partner, although both forms of violence occur within the family. This article explains the differential response to these forms of family violence through a historical examination of the movements to combat child abuse and intimate partner violence, including the influence of first- and second-wave feminism. The author applies theories of social control to analyze the development of the social response. She argues that an integration of the social service and criminal justice systems would best serve families who are experiencing violence.
Does Social Network Matter in Knowledge Output?
Authors: G.D. Bino Paul , M. Krishna
Published: May 2011

This paper examines two important aspects of knowledge output: the degree of concentration in knowledge output and the nature of social network, taking the Economic and Political Weekly (EPW), a known scholarly periodical in the social sciences, as a case. We analyse the author data, looking at the frequency distribution of authors against the number of papers published and the social network of authors during the period 1996–2005. While the degree of concentration is assessed using a power law, namely Lotka’s law, the co-author data is transformed to a symmetric sociogram. The study covers 1,803 authors who published research articles in the EPW, including contributions by social scientists, policy professionals and scientists. It appears the progress in Indian social science has an apparent link with the history of EPW, accounting for a significant part of intellectual output and scholarly discourses in Indian social science. Taking cues from scholarly lineages, which investigate knowledge as a social phenomenon including the sociology of science, economics of knowledge and social network theory, we examine an important question: What is the degree of concentration prevailing in the EPW, during 1996–2005? Does the social network of authors, captured from the data, provide explanations for the degree of concentration? Our analysis shows that a high degree of the concentration of the authors and a relatively organised social network of authors coexist, indicating that the concentration in knowledge output, perhaps, is inherently linked to the structure.
Central Role of GABA in Neuron–Glia Interactions
Authors: Vélez-Fort Mateo , Audinat Etienne , Angulo María Cecilia
Published: May 2011

The major types of glial cells—astrocytes, microglia, and cells of the oligodendroglial lineage—are known to express functional metabotropic and ionotropic GABA receptors. Neuronal signaling mechanisms allowing for the activation of these receptors in glia are probably as complex as those described among neurons and involve synaptic and extrasynaptic transmission modes. In addition, astrocytes can signal back to neurons by releasing GABA, probably through unconventional nonvesicular mechanisms. The decryption of the roles played by GABAergic signaling in neuron–glia interactions is only beginning, but it has been suggested that activation of glial cells by GABA influences important functions of the brain such as neuronal activity, differentiation, myelination, and neuroprotection. This review discusses the cellular mechanisms allowing the major types of glial cells to sense and transmit GABAergic signals and gives an overview of potential roles of this signaling pathway in developing and mature brains.
Marxism and Islamism: Intellectual conformity in Aron’s time and our own
Authors: Baehr Peter
Published: May 2011

We celebrate great writers not only by reconstructing their ideas but also by thinking in their spirit. Many aspects of Raymond Aron’s legacy could, today, be exploited by writers of an Aronian turn of mind. They might draw on his philosophy of history; his defense of the specificity of politics; his acute awareness of the burdens of responsibility imposed on great powers. In this article, I flag a different topic: Aron’s concern with the impact of regimes and local cultures on political discussion. Of special interest to him were state-sponsored ideology and self-induced groupthink (the ‘opium of the intellectuals’). After briefly describing Aron’s views of both of these phenomena within the context of official and unofficial Marxism, I examine two modalities of communicative inhibition that have emerged since his death. Both turn on the emergence of Islamism as a major modern political ideology; both entail impediments to free speech: the vilification of political disagreement as ‘phobic’ and, relatedly, the political use of law (‘lawfare’) to halt debate on matters sensitive to Islamists.
Raymond Aron’s engagement with Weber: Recovery or retreat?
Authors: Breiner Peter
Published: May 2011

This article traces the arc of Aron’s interpretation of Weber from his dynamic political reading of Weber’s sociology to his deflationary criticism, a criticism that robs Weber’s sociology, in particularly his political sociology, of the very force that led Aron to embrace it in the first place. At the outset I trace Aron’s stylized dynamic political reading of Max Weber’s historical sociology, political sociology, and sociologically informed political ethics, a reading in which Weber’s interpretive notion of meaningful action and his notion of counterfactual judgment in providing explanation become central to Weber’s political sociology. I show how for Aron Weber’s historical sociology in general and his political sociology in particular serve to provide a model for how sociology can clarify for political actors the existential political choices they may face in making decisions. But I also argue that when Aron subsequently turns to a criticism of Weber in the name of cleansing his theory of political extremity, he undermines all the dynamic elements in Weber’s political sociology so central to his original interpretation. The upshot of this move is that he comes up with a concept of political sociology that is static, structurally rigid, and curiously time-bound. Thus precisely the moderation and restraint for which Aron is so frequently praised become fundamental weaknesses when we examine his revision of Weber’s political sociology and its meaning for a sociologically informed political judgment.
In search of limits: Raymond Aron on ‘secular religion’ and communism
Authors: Gordon Daniel
Published: May 2011

Beginning in the 1940s, Raymond Aron used the concept of ‘secular religion’ to condemn communism. This article traces the history of ‘secular religion’ within his writings. Aron’s earliest critique of communism, in his doctoral thesis of 1938, entitled Introduction to the Philosophy of History , was philosophically powerful yet did not rely on ‘secular religion.’ The concept first emerged in his wartime writings; it then became central in his famous book The Opium of the Intellectuals (1955). The ambiguities of the concept of ‘secular religion’ are discussed in this article. On the whole, the idea of ‘secular religion’ appears to be a weak spot within the corpus of a thinker who was usually very precise in defining his concepts. The article suggests that Aron is a case study in the failure of many Cold War intellectuals to wrestle productively with the concept of religion.
Vildagliptin as an add-on agent in type 2 diabetes in a multi-ethnic UK clinic: a single-centre audit
Authors: De Parijat , Mozdiak Ella , Andrews Chris , Geransar Parnia
Published: May 2011

The dipeptidyl peptidase-4 (DPP-4) inhibitor vildagliptin improves glycaemic control in patients with type 2 diabetes mellitus. In Europe vildagliptin is indicated for use in patients with type 2 diabetes inadequately controlled by lifestyle measures plus an oral antidiabetic drug (OAD) — metformin, a sulphonylurea or a thiazolidinedione. This audit examined the effects of vildagliptin added to one, two or three other OADs (in 13, 12 and five patients, respectively). Glycated haemoglobin A1C (HbA1C) was reduced in 70% of patients (61.5%, 75% and 80% on dual, triple and quadruple therapy, respectively). Mean HbA 1C level decreased from 8.9% to 7.9% (p=0.012). The largest reduction was in African-Caribbean patients (-1.3%). No significant changes in weight, blood pressure or liver function occurred.
A national strategic approach to diabetic foot disease in Scotland: changing a culture
Authors: Leese Graham P , Stang Duncan , Mcknight John A ,   Scottish Diabetes Foot Action Group
Published: May 2011

A diabetes foot action plan was introduced to Scotland in 2006. This has included developing a foot-screening programme with foot risk stratification. Currently 140,000 people (61% of all patients with diabetes) have undergone foot risk stratification, with 69% categorised as low risk, 20% as moderate risk and 11% as being at high risk of foot ulceration. This has helped support the introduction of needs-related care pathways. Schemes to support community-based podiatrists and strengthen links and referral pathways to specialist foot services have been introduced. Identifying key competencies for podiatrists and orthotists working for patients with diabetes has underpinned the development of a competency framework for each profession. Nationally agreed and utilised patient education leaflets and staff education programmes, including online training programmes have been introduced. Surveys of multidisciplinary foot services, have shown amongst other things, a low level of consultant involvement in such clinics (58% of Health Boards). Overall, national data indicated that across Scotland in 2009 the prevalence of foot ulceration was 2.5% in December 2010 and amputation was 0.5% in 2009, the latter having declined from 0.8% in 2003.
The superiority of the time-to-event continual reassessment method to the rolling six design in pediatric oncology Phase I trials
Authors: Zhao Lili , Lee Julia , Mody Rajen , Braun Thomas M
Published: May 2011

Background The rolling six design (RSD) is currently being used by the Children’s Oncology Group (COG) as their standard design for Phase I trials. Because the COG has large multi-center trials with fast accrual, the motivation for adopting the RSD is to hasten accrual and shorten the duration of their trials. However, trial suspension due to completion of follow-up still cannot be entirely avoided by the RSD. Therefore, a design that allows continuous enrollment of patients throughout the entire trial is needed.

Purpose To demonstrate the superior performance of the Time-to-Event Continual Reassessment Method (TITE-CRM) with continuous patient recruitment relative to the RSD, in terms of identifying the maximum tolerated dose (MTD) and reducing exposure of patients to toxic doses.

Methods Using scenarios that were based on an actual pediatric Phase I trial at the University of Michigan, Monte Carlo simulations were used to investigate the operational characteristics of RSD and TITE-CRM.

Results The TITE-CRM treated all available patients, identified the MTD more accurately than the RSD and did not increase the probability of exposing patients to toxic doses.

Limitations Both the TITE-CRM and RSD assume that the probability of dose limiting toxicity increases with higher dose level.

Conclusions The TITE-CRM, which allows for continual enrollment of patients, provides a safe design for pediatric oncology Phase I trials with better accuracy than the RSD.
Parametric analysis of the thermal performance of light steel residential buildings in Csb climatic regions
Authors: Santos P , Simões da Silva L , Gervásio H , Gameiro Lopes A
Published: May 2011

In this article, the passive thermal performance of a light steel residential building is studied. A numerical model is implemented and is experimentally validated. The analysis is focussed on the Csb climatic region. Subsequently, this calibrated model is used to assess the importance of several parameters (ventilation, thermal insulation, overhangs shading, windows shade devices, and windows glazing) in the summer and winter thermal performance of this building. Subsequently, based on the cooling and heating seasons thermal performance, an optimum building envelope and operational solution is specified for average Csb climate conditions. Finally, design guidance is provided for the specification of building components and the operation of the building for the range of climatic conditions within the Csb climatic region.
Methotrexate: Optimizing the Efficacy in Rheumatoid Arthritis
Authors: Braun Jürgen
Published: May 2011

Methotrexate (MTX) is currently the most frequently used drugs in the treatment of rheumatoid arthritis (RA). The drug had been synthesized in 1948 and first tests to treat patients with psoriasis and RA were published in 1951. However, until the 1980s there was only limited use of MTX in the treatment of RA. Since the 1990s MTX is the disease-modifying antirheumatic drug (DMARD) of first choice for the treatment of RA in most countries worldwide. By definition, DMARDs in RA are those compounds for which an inhibiting effect on radiographic progression has been demonstrated. Several combinations of DMARDs have been tested, most commonly with MTX as the anchor drug. Regarding the route of administration of MTX there is some evidence that the parenteral route, most often performed subcutaneously, has some additional benefits over the oral route. In MTX monotherapy, dosages up to 30 mg/week are now used. There are now three main combinations that are playing an important role: MTX + sulfasalazine (SSZ) + hydroxychloroquine, MTX + leflunomide (LEF), and MTX + biologics such as antitumour necrosis factor (anti-TNF) and other new compounds which block the interleukin 6 (IL6) receptor or T-cell activation and delete B cells. Regarding clinical efficacy, MTX monotherapy has performed almost similarly well in comparison with biologic mono-therapy, both usually combined with glucocorticoids. However, structural damage is usually inhibited to a significantly greater degree with the biologics. The combination of MTX with biologics has proven superior to either agent alone in all aspects. Current strategic regimens which concentrate on systematic ways to bring patients into remission all include MTX as first choice.
Numerical simulation of instability conditions in multiple pinion drives
Authors: Zhang K-Z , Yu H-D , Zeng X-X , Lai X-M
Published: May 2011

Multiple pinion drives, parallel arrangements of the pinions for large torque transmission, are widely utilized in various heavy-duty industrial applications. For such multi-mesh gear systems, periodic mesh stiffnesses could possibly cause parametric instabilities and server vibrations. Based on the Floquet–Lyapunov theory, numerical simulations are conducted to determine the parametric instability status. For rectangular waveforms assumption of the mesh stiffness variations, the primary, secondary, and combination instabilities of the multiple pinion drives are studied. The effects of mesh stiffness parameters, including mesh frequencies, stiffness variation amplitudes, and mesh phasing, on these instabilities are yielded. Unstable regions are also indicated for different gear pair configurations. Instability conditions of three-pinion drives are obtained and compared with those of the three-stage gear train.
Numerical investigations of vortex flows and vortex suppression schemes in a large pumping-station sump
Authors: Tang X L , Wang F J , Li Y J , Cong G H , Shi X Y , Wu Y L , Qi L Y
Published: May 2011

This work uses a commercial computational fluid dynamics code to predict three-dimensional (3D) vortex flows in a large centrifugal-pump station under construction in China and proposes relevant vortex-eliminating schemes. Because of the complex nature of the vortex flows in sumps, different turbulence models, namely, standard k–ε, re-normalization group k–ε and realizable k–ε models, are first used to investigate their feasibility in predicting flows in a small physical model of an open pump sump, and various vortex streamlines and strength in the sump are predicted, analysed, and compared with the experimental data. The comparisons show that the realizable k–ε model predicts the position and strength of free-surface, sidewall-attached, and floor-attached vortices more accurately than the other two models. Then, the realizable k–ε model is used here to investigate 3D vortex flows in a large pumping-station sump. All the various vortices, such as free-surface, wall-attached vortices, are successfully predicted. Thus, based on the information of location, shape, size, and strength of the calculated vortices, three types of vortex-eliminating devices are proposed and their corresponding vortex suppression effects are analysed. These results will be used as reference for the safe and stable operation of the Hui–Nan–Zhuang pumping station in the future.
MimoPro: a more efficient Web-based tool for epitope prediction using phage display libraries
Authors: Chen Wen Han , Sun Ping Ping , Lu Yang , Guo William W , Huang Yan Xin , Ma Zhi Qiang
Published: May 2011

Background

A B-cell epitope is a group of residues on the surface of an antigen which stimulates humoral responses. Locating these epitopes on antigens is important for the purpose of effective vaccine design. In recent years, mapping affinity-selected peptides screened from a random phage display library to the native epitope has become popular in epitope prediction. These peptides, also known as mimotopes, share the similar structure and function with the corresponding native epitopes. Great effort has been made in using this similarity between such mimotopes and native epitopes in prediction, which has resulted in better outcomes than statistics-based methods can. However, it cannot maintain a high degree of satisfaction in various circumstances.

Results

In this study, we propose a new method that maps a group of mimotopes back to a source antigen so as to locate the interacting epitope on the antigen. The core of this method is a searching algorithm that is incorporated with both dynamic programming (DP) and branch and bound (BB) optimization and operated on a series of overlapping patches on the surface of a protein. These patches are then transformed to a number of graphs using an adaptable distance threshold (ADT) regulated by an appropriate compactness factor (CF), a novel parameter proposed in this study. Compared with both Pep-3D-Search and PepSurf, two leading graph-based search tools, on average from the results of 18 test cases, MimoPro, the Web-based implementation of our proposed method, performed better in sensitivity, precision, and Matthews correlation coefficient (MCC) than both did in epitope prediction. In addition, MimoPro is significantly faster than both Pep-3D-Search and PepSurf in processing.

Conclusions

Our search algorithm designed for processing well constructed graphs using an ADT regulated by CF is more sensitive and significantly faster than other graph-based approaches in epitope prediction. MimoPro is a viable alternative to both PepSurf and Pep-3D-Search for epitope prediction in the same kind, and freely accessible through the MimoPro server located at http://informatics.nenu.edu.cn/MimoPro.
Adaptation to HIF-1 deficiency by upregulation of the AMP/ATP ratio and phosphofructokinase activation in hepatomas
Authors: Golinska Monika , Troy Helen , Chung Yuen-Li , McSheehy Paul M , Mayr Manuel , Yin Xiaoke , Ly Lucy , Williams Kaye J , Airley Rachel E , Harris Adrian L , Latigo John , Perumal Meg , Aboagye Eric O , Perrett David , Stubbs Marion , Griffiths John R
Published: May 2011

Background

HIF-1 deficiency has marked effects on tumour glycolysis and growth. We therefore investigated the consequences of HIF-1 deficiency in mice, using the well established Hepa-1 wild-type (WT) and HIF-1β-deficient (c4) model. These mechanisms could be clinically relevant, since HIF-1 is now a therapeutic target.

Methods

Hepa-1 WT and c4 tumours grown in vivo were analysed by 18FDG-PET and 19FDG Magnetic Resonance Spectroscopy for glucose uptake; by HPLC for adenine nucleotides; by immunohistochemistry for GLUTs; by immunoblotting and by DIGE followed by tandem mass spectrometry for protein expression; and by classical enzymatic methods for enzyme activity.

Results

HIF-1β deficient Hepa-1 c4 tumours grew significantly more slowly than WT tumours, and (as expected) showed significantly lower expression of many glycolytic enzymes. However, HIF-1β deficiency caused no significant change in the rate of glucose uptake in c4 tumours compared to WT when assessed in vivo by measuring fluoro-deoxyglucose (FDG) uptake. Immunohistochemistry demonstrated less GLUT-1 in c4 tumours, whereas GLUT-2 (liver type) was similar to WT. Factors that might upregulate glucose uptake independently of HIF-1 (phospho-Akt, c-Myc) were shown to have either lower or similar expression in c4 compared to WT tumours. However the AMP/ATP ratio was 4.5 fold higher (p < 0.01) in c4 tumours, and phosphofructokinase-1 (PFK-1) activity, measured at prevailing cellular ATP and AMP concentrations, was up to two-fold higher in homogenates of the deficient c4 cells and tumours compared to WT (p < 0.001), suggesting that allosteric PFK activation could explain their normal level of glycolysis. Phospho AMP-Kinase was also higher in the c4 tumours.

Conclusions

Despite their defective HIF-1 and consequent down-regulation of glycolytic enzyme expression, Hepa-1 c4 tumours maintain glucose uptake and glycolysis because the resulting low [ATP] high [AMP] allosterically activate PFK-1. This mechanism of resistance would keep glycolysis functioning and also result in activation of AMP-Kinase and growth inhibition; it may have major implications for the therapeutic activity of HIF inhibitors in vivo. Interestingly, this control mechanism does not involve transcriptional control or proteomics, but rather the classical activation and inhibition mechanisms of glycolytic enzymes.
Back and neck pain are related to mental health problems in adolescence
Authors: Rees Clare S , Smith Anne J , O'Sullivan Peter B , Kendall Garth E , Straker Leon M
Published: May 2011

Background

There is a high prevalence of mental health problems amongst adolescents. In addition there is a high prevalence of spinal pain in this population. Evidence suggests that these conditions are related. This study sought to extend earlier findings by examining the relationship between mental health problems as measured by the Child Behaviour Check List (CBCL) and the experience of back and neck pain in adolescents.

Methods

One thousand five hundred and eighty participants (mean age 14.1 years) from the Western Australian Pregnancy (Raine) Study provided cross-sectional spinal pain and CBCL data.

Results

As predicted, there was a high prevalence of back and neck pain in this cohort. On the whole, females reported more mental health difficulties than males. There were strong relationships between the majority of symptom scales of the CBCL and back and neck pain. Scores on the CBCL were associated with higher odds of comorbid back and neck pain.

Conclusions

These findings strongly support the need to consider both psychological and pain symptoms when providing assessments and treatment for adolescents. Further research is required to inform causal models.
The HPV-16 E7 oncoprotein induces centriole multiplication through deregulation of Polo-like kinase 4 expression
Authors: Korzeniewski Nina , Treat Benjamin , Duensing Stefan
Published: May 2011

Background

Infection with high-risk human papillomaviruses (HPVs) such as HPV-16 is intimately associated with squamous cell carcinomas (SCCs) of the anogenital tract and a subset of oropharyngeal carcinomas. Such lesions, including pre-invasive precursors, frequently show multipolar mitoses and aneuploidy. The high-risk HPV-16-encoded E7 oncoprotein has been shown to rapidly induce centrosome abnormalities thereby causing the formation of supernumerary mitotic spindle poles and increasing the risk for chromosome missegregation. HPV-16 E7 has been found to rapidly induce centriole overduplication, in part, through the simultaneous formation of more than one daughter centriole at single maternal centrioles (centriole multiplication). The precise molecular mechanism that underlies HPV-16 E7-induced centriole multiplication, however, remains poorly understood.

Findings

Here, we show that human keratinocytes engineered to stably express the HPV-16 E7 oncoprotein exhibit aberrant Polo-like kinase 4 (PLK4) protein expression at maternal centrioles. Real-time quantitative reverse transcriptase (qRT-PCR) analysis of these cells revealed an increase of PLK4 mRNA levels compared to control cells. Importantly, the ability of the HPV-16 E7 oncoprotein to induce centriole multiplication was found to correlate with its ability to activate the PLK4 promoter and to up-regulate PLK4 mRNA.

Conclusions

These results highlight the critical role of PLK4 transcriptional deregulation in centriole multiplication in HPV-16 E7-expressing cells. Our findings encourage further experiments to test transcriptional inhibitors or small molecules targeting PLK4 to prevent centriole abnormalities, mitotic infidelity and malignant progression in HPV-associated neoplasms and other tumors in which PLK4 regulation is disrupted.
A stable TTI reverse time migration and its implementation
Authors: Zhang Yu , Zhang Houzhu , Zhang Guanquan
Published: May 2011

Modeling and reverse time migration based on the tilted transverse isotropic (TTI) acoustic wave equation suffers from instability in media of general inhomogeniety, especially in areas where the tilt abruptly changes. We develop a stable TTI acoustic wave equation implementation based on the original elastic anisotropic wave equation. We, specifically, derive a vertical transversely isotropic wave system of equations that is equivalent to their elastic counterpart and introduce the self-adjoint differential operators in rotated coordinates to stabilize the TTI acoustic wave equations. Compared to the conventional formulations, the new system of equations does not add numerical complexity; a stable solution can be found by either a pseudospectral method or a high-order explicit finite difference scheme. We demonstrate by examples that our method provides stable and high-quality TTI reverse time migration images.
Traveltime approximations for transversely isotropic media with an inhomogeneous background
Authors: Alkhalifah Tariq
Published: May 2011

A transversely isotropic (TI) model with a tilted symmetry axis is regarded as one of the most effective approximations to the Earth subsurface, especially for imaging purposes. However, we commonly utilize this model by setting the axis of symmetry normal to the reflector. This assumption may be accurate in many places, but deviations from this assumption will cause errors in the wavefield description. Using perturbation theory and Taylor’s series, I expand the solutions of the eikonal equation for 2D TI media with respect to the independent parameter [Formula: see text], the angle the tilt of the axis of symmetry makes with the vertical, in a generally inhomogeneous TI background with a vertical axis of symmetry. I do an additional expansion in terms of the independent (anellipticity) parameter [Formula: see text] in a generally inhomogeneous elliptically anisotropic background medium. These new TI traveltime solutions are given by expansions in [Formula: see text] and [Formula: see text] with coefficients extracted from solving linear first-order partial differential equations. Pade approximations are used to enhance the accuracy of the representation by predicting the behavior of the higher-order terms of the expansion. A simplification of the expansion for homogenous media provides nonhyperbolic moveout descriptions of the traveltime for TI models that are more accurate than other recently derived approximations. In addition, for 3D media, I develop traveltime approximations using Taylor’s series type of expansions in the azimuth of the axis of symmetry. The coefficients of all these expansions can also provide us with the medium sensitivity gradients (Jacobian) for nonlinear tomographic-based inversion for the tilt in the symmetry axis.
Anisotropic P-SV-wave dispersion and attenuation due to inter-layer flow in thinly layered porous rocks
Authors: Krzikalla Fabian , Müller Tobias M.
Published: May 2011

Elastic upscaling of thinly layered rocks typically is performed using the established Backus averaging technique. Its poroelastic extension applies to thinly layered fluid-saturated porous rocks and enables the use of anisotropic effective medium models that are valid in the low- and high-frequency limits for relaxed and unrelaxed pore-fluid pressures, respectively. At intermediate frequencies, wave-induced interlayer flow causes attenuation and dispersion beyond that described by Biot’s global flow and microscopic squirt flow. Several models quantify frequency-dependent, normal-incidence P-wave propagation in layered poroelastic media but yield no prediction for arbitrary angles of incidence, or for S-wave-induced interlayer flow. It is shown that generalized models for P-SV-wave attenuation and dispersion as a result of interlayer flow can be constructed by unifying the anisotropic Backus limits with existing P-wave frequency-dependent interlayer flow models. The construction principle is exact and is based on the symmetry properties of the effective elastic relaxation tensor governing the pore-fluid pressure diffusion. These new theories quantify anisotropic P- and SV-wave attenuation and velocity dispersion. The maximum SV-wave attenuation is of the same order of magnitude as the maximum P-wave attenuation and occurs prominently around an angle of incidence of [Formula: see text]. For the particular case of a periodically layered medium, the theoretical predictions are confirmed through numerical simulations.
VP/VS ratio and shear-wave splitting in the Nankai Trough seismogenic zone: Insights into effective stress, pore pressure, and sediment consolidation
Authors: Tsuji Takeshi , Dvorkin Jack , Mavko Gary , Nakata Norimitsu , Matsuoka Toshifumi , Nakanishi Ayako , Kodaira Shuichi , Nishizawa Osamu
Published: May 2011

To estimate variation of stress state and sediment consolidation in the Nankai plate subduction zone off southwest Japan, we measured the P-wave to S-wave velocity ratio (VP/VS) and S-wave splitting along the seismic line extending from the trench to the seismogenic zone. For this purpose, we used active-source seismic data recorded by multicomponent ocean bottom seismometers (OBS). Because it is difficult to identify the PS-converted reflection waveforms for each of the geological boundaries in this deep offshore region, we focused on the more easily identified PPS-refracted waveforms that register the conversion of the up-going P-waves to S-waves at the igneous crust surface. We estimated the average VP/VS ratio within the sedimentary section by using the time lag between the P-refracted waves and PPS-converted waves. This VP/VS ratio changes abruptly at the trough axis (i.e., the deformation front of the accretionary prism) arguably because of compaction associated with the accretion process. We observed relatively high VP/VS around the seismogenic megasplay fault, which may partially indicate the abnormal pore pressure and intensive fractures associated with the fault. To estimate the stress-induced fracture orientation and stress magnitude, we computed the fast S-wave polarization direction and estimated S-wave velocity anisotropy by applying the crosscorrelation method to the PPS-converted waves. To improve signal-to-noise ratio of the waveform for S-wave splitting analysis, we stacked PPS-converted waveforms on receiver gather. These anisotropic characteristics change at the seismogenic megasplay fault: the fast polarization direction is nearly parallel to the subduction direction seaward of the megasplay fault and is perpendicular to the subduction direction landward of the megasplay fault. This velocity anisotropy is especially strong around the megasplay fault. These results imply that the preferred fracture orientation, as well as the principal stress orientation, is oblique to the direction of plate subduction near the megasplay fault.
Toward phenomenological universality of the mechanical behavior of arbitrarily anisotropic porous rocks
Authors: Rasolofosaon Patrick N. J.
Published: May 2011

The great diversity of the microstructures of rocks impedes the use of a universal rock physics model with idealized geometry to correctly describe the mechanical behavior of rocks. In this quest for universality, by ignoring the detailed description of the causes of the observed phenomenon and only focusing on the empirical relation between the cause (applied stress) and the effect (resulting strain), phenomenological models such as the linear elastic Hooke’s law roughly describe the mechanical behavior of rocks of contrasted microstructures. However, in detail, numerous laboratory experiments covering broad frequency and strain ranges (both typically more than eight orders of magnitude) on various types of rocks have also shown deviations from Hooke’s law due to anisotropy, frequency dependence, nonlinearity, possibly with the presence of hysteresis, and poroelasticity. A phenomenological model has been recently proposed that synthesizes all these behaviors in a single model, but unfortunately does not integrate the porous nature of rocks. The new model is based on a reformulation in modified spectral decomposition of the previous work using the 7D poroelastic tensor linking the dynamic parameters (i.e., the six stress components and fluid pressure) and the kinematic parameters (i.e., the six strain components and the local increase of fluid content ζ). In addition to the elastic hysteresis of the stress-strain curves, the model also predicts the existence of a second hysteresis, or hydraulic hysteresis, of the curve fluid pressure p versus fluid content ζ, qualitatively similar to the first one. Indeed, the elastic hysteresis is due to the opening and the closure of some compliant pores at different stress levels. These pores represent possible access radii for the saturating fluid; the hysteresis in the geometry of the porous network also induces the hydraulic hysteresis in the p-ζ curves.
Analysis of fluid substitution in a porous and fractured medium
Authors: Sil Samik , Sen Mrinal K. , Gurevich Boris
Published: May 2011

To improve quantitative interpretation of seismic data, we analyze the effect of fluid substitution in a porous and fractured medium on elastic properties and reflection coefficients. This analysis uses closed-form expressions suitable for fluid substitution in transversely isotropic media with a horizontal symmetry axis (HTI). For the HTI medium, the effect of changing porosity and water saturation on (1) P-wave moduli, (2) horizontal and vertical velocities, (3) anisotropic parameters, and (4) reflection coefficients are examined. The effects of fracture density on these four parameters are also studied. For the model used in this study, a 35% increase in porosity lowers the value of P-wave moduli by maximum of 45%. Consistent with the reduction in P-wave moduli, P-wave velocities also decrease by maximum of 17% with a similar increment in porosity. The reduction is always larger for the horizontal P-wave modulus than for the vertical one and is nearly independent of fracture density. The magnitude of the anisotropic parameters of the fractured medium also changes with increased porosity depending on the changes in the value of P-wave moduli. The reflection coefficients at an interface of the fractured medium with an isotropic medium change in accordance with the above observations and lead to an increase in anisotropic amplitude variation with offset (AVO) gradient with porosity. Additionally, we observe a maximum increase in P-wave modulus and velocity by 30% and 8%, respectively, with a 100% increase in water saturation. Water saturation also changes the anisotropic parameters and reflection coefficients. Increase in water saturation considerably increases the magnitude of the anisotropic AVO gradient irrespective of fracture density. From this study, we conclude that porosity and water saturation have a significant impact on the four studied parameters and the impacts are seismically detectable.
Phased array compaction cell for measurement of the transversely isotropic elastic properties of compacting sediments
Authors: Nihei Kurt T. , Nakagawa Seiji , Reverdy Frederic , Myer Larry R. , Duranti Luca , Ball Greg
Published: May 2011

Sediments undergoing compaction typically exhibit transversely isotropic (TI) elastic properties. We present a new experimental apparatus, the phased array compaction cell, for measuring the TI elastic properties of clay-rich sediments during compaction. This apparatus uses matched sets of P- and S-wave ultrasonic transducers located along the sides of the sample and an ultrasonic P-wave phased array source, together with a miniature P-wave receiver on the top and bottom ends of the sample. The phased array measurements are used to form plane P-waves that provide estimates of the phase velocities over a range of angles. From these measurements, the five TI elastic constants can be recovered as the sediment is compacted, without the need for sample unloading, recoring, or reorienting. This paper provides descriptions of the apparatus, the data processing, and an application demonstrating recovery of the evolving TI properties of a compacting marine sediment sample.
Elastic anisotropy estimation from laboratory measurements of velocity and polarization of quasi-P-waves using laser interferometry
Authors: Lebedev Maxim , Bóna Andrej , Pevzner Roman , Gurevich Boris
Published: May 2011

A new method for conducting laboratory measurements of the velocities and polarizations of compressional and shear waves in rock samples uses a laser Doppler interferometer (LDI). LDI can measure the particle velocity of a small (0.03 mm2) element of the surface of the sample along the direction of the laser beam. By measuring the particle velocity of the same surface element in three linearly independent directions and then transforming those velocities to Cartesian coordinates, three orthogonal components of the particle-velocity vector are obtained. Thus, LDI can be used as a localized three-component (3C) receiver of ultrasonic waves, and, together with a piezoelectric transducer as a source, it can simulate a 3C seismic experiment in the laboratory. Performing such 3C measurements at various locations on the surface of the sample produces a 3C seismogram, which can be used to separate the P-wave and two S-waves and to find the polarizations and traveltimes of those waves. Then, the elasticity tensor of the medium can be obtained by minimizing the misfit between measured and predicted polarizations and traveltimes. Computation of the polarizations and traveltimes of body waves inside a sample with a given elasticity tensor is based on the Christoffel equation. The predicted polarizations on the surface then are obtained using the anisotropic Zoeppritz equations. The type of velocity measured (phase or group velocity) depends on the acquisition geometry and the material properties. This is taken into account in the inversion procedure. A “walkaway” laboratory experiment demonstrates the high accuracy of this method.
Correction for the influence of velocity lenses on nonhyperbolic moveout inversion for VTI media
Authors: Takanashi Mamoru , Tsvankin Ilya
Published: May 2011

Nonhyperbolic moveout analysis plays an increasingly important role in velocity model building because it provides valuable information for anisotropic parameter estimation. However, lateral heterogeneity associated with stratigraphic lenses such as channels and reefs can significantly distort the moveout parameters, even when the structure is relatively simple. We analyze the influence of a low-velocity isotropic lens on nonhyperbolic moveout inversion for horizontally layered VTI (transversely isotropic with a vertical symmetry axis) models. Synthetic tests demonstrate that a lens can cause substantial, laterally varying errors in the normal-moveout velocity [Formula: see text] and the anellipticity parameter [Formula: see text]. The area influenced by the lens can be identified using the residual moveout after the nonhyperbolic moveout correction as well as the dependence of errors in [Formula: see text] and [Formula: see text] on spreadlength. To remove such errors in [Formula: see text] and [Formula: see text], we propose a correction algorithm designed for a lens embedded in a horizontally layered overburden. This algorithm involves estimation of the incidence angle of the ray passing through the lens for each recorded trace. With the assumption that lens-related perturbation of the raypath is negligible, the lens-induced traveltime shifts are computed from the corresponding zero-offset time distortion (i.e., from “pull-up” or “push-down” anomalies). Synthetic tests demonstrate that this algorithm substantially reduces the errors in the effective and interval parameters [Formula: see text] and [Formula: see text]. The corrected traces and reconstructed “background” values of [Formula: see text] and [Formula: see text] are suitable for anisotropic time imaging and producing a high-quality stack.
Visual and Colorimetric Detection of Cyanide Anion Based on a “Turn-off” Daylight Fluorescent Molecule
Authors: Jiao Lijuan , Liu Mingming , Zhang Min , Yu Changjiang , Wang Zhaoyun , Hao Erhong
Published: May 2011

A strong daylight-fluorescent boron dipyrromethene (BODIPY) derivative 1 has been synthesized for the visual and colorimetric detection of cyanide anion in solution. BODIPY 1 shows a glow characteristic of daylight-fluorescent material since emitted fluorescent light has been added to the simple reflection light under daylight illumination. This green daylight fluorescence is diminished upon interaction with cyanide anion, resulting in a highly selective and sensitive naked-eye detection of cyanide anion over other common anions.
Polyoxomolybdate–Surfactant Hybrid Layered Crystal with Unusually Long Periodicity
Authors: Ito Takeru , Mikurube Keisuke , Hasegawa Kimiko , Kurasawa Mariko , Naruke Haruo , Ozeki Tomoji
Published: May 2011

An inoranic–organic hybrid crystal was synthesized by using polyoxomolybdate and hexadecylpyridinium surfactant. The unit cell was monoclinic having quite a long cell dimension (b = 75.0111(14) Å). The crystal structure was formed by alternative stacking of β-octamolybdate bilayers and interdigitated hexadecylpyridinium bilayers with layered periodicity of 3.75 nm, which is the largest value for polyoxometalate–surfactant hybrid crystals.
Ferrocene-appended Subporphyrins
Authors: Sugimoto Hisashi , Tanaka Takayuki , Osuka Atsuhiro
Published: May 2011

meso-Tris(4-ferrocenylphenyl)subporphyrin 1 and meso-triferrocenylsubporphyrin 2 were prepared. The structure of 2 was confirmed by X-ray analysis. Both molecules exhibit substantially red-shifted absorption spectra and almost complete fluorescence quenching, due to the influence of the electron-donating ferrocene substituents. Subporphyrin 1 exhibits a nonsplit oxidation wave for the oxidation of the ferrocene moieties, while subporphyrin 2 exhibits a split reversible oxidation wave with ΔE = 168 mV to indicate effective electronic communication.
Total Synthesis of Doubly Locked 5Za15Ea-Biliverdin Derivative: A Convergent Synthesis of the E-anti Dipyrrole Component Locked with a 7-Membered Ring
Authors: Chen Liyi , Iwamoto Ryoji , Ukaji Yutaka , Inomata Katsuhiko
Published: May 2011

Doubly locked 5Za15Ea-biliverdin (BV) derivative was synthesized toward the investigation of stereochemistry and function of the Pfr-form chromophore in bacteriophytochromes. A convergent synthetic method was established for the locked E-anti dipyrrole component with a 7-membered ring.
Effect of Inorganic Salt on Formation of Porous PLGA Microspheres
Authors: Takai Chika , Hotta Tadashi , Shiozaki Shuji , Matsumoto Shuhei , Fukui Takehisa
Published: May 2011

Porous microspheres were prepared by a solid-in-oil-in-water (S/O/W) emulsion. Effects of inorganic salt on pore formation were investigated. Sodium chloride (NaCl) is a proper pore inducing agent, and large uniform pores were obtained with addition of 0.5 M NaCl.
Synthesis and Photochromic Properties of [2.2]Thiophenophan-8-ene-1,2-diol
Authors: Takeshita Michinori , Yamaguchi Shouhei
Published: May 2011

A photochromic [2.2]thiophenophan-8-ene-1,2-diol, which is the first ethylene-bridged dithienylethene, has been synthesized by pinacol coupling and this compound indicates fairly good photochromic properties such as high quantum yield for photocyclization and high thermal stability.