bluuebunny/crossref_metadata_2025 huggingface dataset:
The aging neurogenic subventricular zone
Authors: Luo Jie , Daniels Stephen B. , Lennington Jessica B. , Notti Ryan Q. , Conover Joanne C.
Published: February 2006

In the adult mouse brain, the subventricular zone (SVZ) is a neurogenic stem cell niche only 4–5 cell diameters thick. Within this narrow zone, a unique microenvironment supports stem cell self‐renewal, gliogenesis or neurogenesis lineage decisions and tangential migration of newly generated neurons out of the SVZ and into the olfactory bulb. However, with aging, SVZ neurogenesis declines. Here, we examine the dynamic interplay between SVZ cytoarchitecture and neurogenesis through aging. Assembly of high‐resolution electron microscopy images of corresponding coronal sections from 2‐, 10‐ and 22‐month‐old mice into photomontages reveal a thinning of the SVZ with age. Following a 2‐h BrdU pulse, we detect a significant decrease in cell proliferation from 2 to 22 months. Neuroblast numbers decrease with age, as do transitory amplifying progenitor cells, while both SVZ astrocytes and adjacent ependymal cells remain relatively constant. At 22 months, only residual pockets of neurogenesis remain and neuroblasts become restricted to the anterior dorsolateral horn of the SVZ. Within this dorsolateral zone many key components of the younger neurogenic niche are maintained; however, in the aged SVZ, increased numbers of SVZ astrocytes are found interposed within the ependyma. These astrocytes co‐label with markers to ependymal cells and astrocytes, form intercellular adherens junctions with neighboring ependymal cells, and some possess multiple basal bodies of cilia within their cytoplasm. Together, these data reveal an age‐related, progressive restriction of SVZ neurogenesis to the dorsolateral aspect of the lateral ventricle with increased numbers of SVZ astrocytes interpolated within the ependyma.
Quantification of the effects of contrasting crops in the development of soil structure: an organic conversion
Authors: Papadopoulos A. , Mooney S. J. , Bird N. R. A.
Published: February 2006

Soil structure can be greatly affected, and hence manipulated, by agricultural management practices, such as crop rotation. This study aims to illustrate how soil structure under a stockless organic system differed between contrasting crop types using quantified data derived from image analysis. Undisturbed soil samples were collected from five organic conversion strategies in the second year of conversion, during two contrasting seasons in 2001 and following one uniform crop (oats) grown on all the plots in 2004. The samples were impregnated and images of soil structure collected at selected depth intervals. The images were analysed for macroporosity, pore size distribution and pore‐perimeter fractal dimension. Significant differences were found between treatments in terms of overall macroporosity (%) and average pore size (mm2) in 2001. The red clover (Trifolium pratense) treatments had the highest soil macroporosity in 2001, but showed a dramatic drop in 2004 accompanied by a reduction in average pore size (mm2). Pore–perimeter fractal dimensions for four of the five crop treatments in 2001 did not show significant differences. However, there was a significant decrease in the fractal dimensions in 2004, indicating the presence of pores with less rough and irregular pore boundaries following a uniform cereal crop. Benefits to soil structure and porosity from clover were large and significant but were not lasting.
The Effect of Private Insurance on the Health of Older, Working Age Adults: Evidence from the Health and Retirement Study
Authors: Dor Avi , Sudano Joseph , Baker David W.
Published: February 2006

Objective. Primarily, to determine if the presence of private insurance leads to improved health status, as measured by a survey‐based health score. Secondarily, to explore sensitivity of estimates to adjustments for endogeneity. The study focuses on adults in late middle age who are nearing entry into Medicare.

Data Sources. The analysis file is drawn from the Health and Retirement Study, a national survey of relatively older adults in the labor force. The dependent variable, an index of 5 health outcome items, was obtained from the 1996 survey. Independent variables were obtained from the 1992 survey. State‐level instrumental variables were obtained from the Area Resources File and the TAXSIM file. The final sample consists of 9,034 individuals of which 1,540 were uninsured.

Study Design. Estimation addresses endogeneity of the insurance participation decision in health score regressions. In addition to ordinary least squares (OLS), two models are tested: an instrumental variables (IV) model, and a model with endogenous treatment effects due to Heckman (1978). Insurance participation and health behaviors enter with a lag to allow their effects to dissipate over time. Separate regressions were run for groupings of chronic conditions.

Principal Findings. The OLS model results in statistically significant albeit small effects of insurance on the computed health score, but the results may be downward biased. Adjusting for endogeneity using state‐level instrumental variables yields up to a six‐fold increase in the insurance effect. Results are consistent across IV and treatment effects models, and for major groupings of medical conditions. The insurance effect appears to be in the range of about 2–11 percent. There appear to be no significant differences in the insurance effect for subgroups with and without major chronic conditions.

Conclusions. Extending insurance coverage to working age adults may result in improved health. By conjecture, policies aimed at expanding coverage to this population may lead to improved health at retirement and entry to Medicare, potentially leading to savings. However, further research is needed to determine whether similar results are found when alternative measures of overall health or health scores are used. Future research should also explore the use of alternative instrumental variables. Preliminary results provide no justification for targeting certain subgroups with susceptibility to certain chronic conditions rather than broad policy interventions.
The Role of Accruals in Asymmetrically Timely Gain and Loss Recognition
Authors: BALL RAY , SHIVAKUMAR LAKSHMANAN
Published: February 2006

We investigate the role of accrual accounting in the asymmetrically timely recognition (incorporation in reported earnings) of gains and losses. Timely recognition requires accruals when it precedes complete realization of the gains and losses in cash. We show that nonlinear accruals models incorporating the asymmetry in gain and loss recognition (timelier loss recognition, or conditional conservatism) offer a substantial specification improvement, explaining substantially more variation in accruals than equivalent linear specifications. Conversely, conventional linear accruals models, by omitting the loss recognition asymmetry, exhibit substantial attenuation bias and offer a comparatively poor specification of the accounting accrual process. Linear specifications also understate the ability of current earnings to predict future cash flows. These findings have implications for our understanding of accrual accounting and conservatism, as well as for researchers estimating discretionary accruals, earnings management, and earnings quality.
Accounting Discretion in Fair Value Estimates: An Examination of SFAS 142 Goodwill Impairments
Authors: BEATTY ANNE , WEBER JOSEPH
Published: February 2006

This study examines Statement of Financial Accounting Standards 142 adoption decisions, focusing on the trade‐off between recording certain current goodwill impairment charges below the line and uncertain future impairment charges included in income from continuing operations. We examine several potentially important economic incentives that firms face when making this accounting choice. We find evidence suggesting that firms' equity market concerns affect their preference for above‐the‐line vs. below‐the‐line accounting treatment, and firms' debt contracting, bonus, turnover, and exchange delisting incentives affect their decisions to accelerate or delay expense recognition. Our study contributes to the accounting choice literature by examining managers' use of discretion when adopting a mandatory accounting change and by developing and testing explicit cross‐sectional hypotheses of the determinants of firms' preferences for immediate below‐the‐line versus delayed above‐the‐line expense recognition.
Discussion of Accounting Discretion in Fair Value Estimates: An Examination of SFAS 142 Goodwill Impairments
Authors: BENS DANIEL A.
Published: February 2006

Beatty and Weber examine an accounting choice that managers made upon adoption of Statement of Financial Accounting Standards 142: whether to record a goodwill asset impairment as a cumulative effect of an accounting change at the time of adoption or delay the recognition of such an impairment to the future (perhaps indefinitely) when they would be recorded as expenses in earnings from continuing operations. The authors consider several factors that might influence management's reporting of transition effects, including contracting, equity market incentives, and regulatory forces. Participants at the 2005 Journal of Accounting Research Conference questioned whether such a complex accounting decision can be captured with simple linear models and noisy proxy variables, while also speculating upon whether the results would generalize to other settings. In this discussion, I summarize Beatty and Weber's research, highlight its contribution to the accounting literature, and provide a record of the main issues raised by the conference participants.
An Analysis of the Theories and Explanations Offered for the Mispricing of Accruals and Accrual Components
Authors: KRAFT ARTHUR , LEONE ANDREW J. , WASLEY CHARLES
Published: February 2006

Numerous accounting studies claim that investors fail to rationally price accrual‐related information and that investors are functionally fixated. This study documents the importance of performing robustness tests when testing economic or behavioral explanations for apparent accounting‐related security mispricing. We find that performing robustness tests that exclude a small number of firm‐year observations (approximately 200 firm‐year observations or about 1% of the entire sample) reveals an inverted U‐shaped relation between buy‐and‐hold abnormal returns and total accruals. An inverted U‐shaped relation is inconsistent with the functional fixation (earnings fixation) hypothesis. We conduct similar robustness tests for the abnormal accrual anomaly and the net operating assets anomaly proposed by other investigators, and also find an inverted U‐shaped relation between buy‐and‐hold abnormal returns and abnormal accruals and net operating assets. These findings are inconsistent with the explanations put forth by those investigators. Such evidence leads us to conclude that the accrual‐related anomalies are unlikely to be due to investors' inability to process accounting information, as suggested by the functional fixation hypotheses tested.
Clinical‐scale expansion of human cytomegalovirus–specific cytotoxic T lymphocytes from peripheral blood mononuclear cells requiring single‐peptide stimulation and feeder cells but not additional antigen‐presenting cells
Authors: Sakagawa Hisako , Azuma Hiroshi , Fujihara Mitsuhiro , Ikeda Hisami
Published: February 2006

BACKGROUND:  The aim of this study was to find a simple and feasible method for ex vivo expansion of human cytomegalovirus (HCMV)‐specific cytotoxic T cells from peripheral blood mononuclear cells (PBMNCs) without the aid of exogenous antigen‐presenting cells (APCs) such as cultured dendritic cells.

STUDY DESIGN AND METHODS:  PBMNCs from three HLA‐A*2402‐seropositive donors were stimulated with HCMV pp65341‐350 peptide on Day 1 and then cultured with interleukin‐2 and allogeneic feeder cells for 3 to 4 weeks. HCMV peptide–specific T cells were purified with HLA‐A*2402/pp65341‐350 tetramer on Days 12 to 13 and harvested on Days 23 to 27.

RESULTS:  The initial numbers of PBMNCs were 2 × 107, 1.5 × 107, and 2.5 × 107 and the increases in HCMV peptide–specific T cells were 3.5 × 104‐, 2.0 × 103‐, and 1.1 × 103‐fold, respectively. The estimated final numbers of tetramer‐positive cells were 9.1 × 107, 9.0 × 106, and 5.3 × 106, respectively. The purities of the tetramer‐positive cell population in culture were 72.6, 75.0, and 80.9 percent, respectively. The cells killed peptide‐pulsed B‐lympoblastoid cell lines and secreted interferon‐γ in a HLA‐restricted manner. They did not have natural killer cell activity or lymphokine activated killer cell activity. Most of them had an effector‐memory phenotype. They did not express killer inhibitory receptors.

CONCLUSION:  This method makes it possible to obtain more than 1 × 107 HCMV‐specific T cells from approximately 2 × 107 to 5 × 107 PBMNCs without exogenous APCs such as cultured dendritic cells.
Functional inactivation of white blood cells by Mirasol treatment
Authors: Fast Loren D. , DiLeone Gilbert , Li Junzhi , Goodrich Raymond
Published: February 2006

BACKGROUND:  The presence of white blood cells (WBCs) in blood products has been shown to contribute to the development of a variety of immune responses including both donor antirecipient and recipient antidonor responses. Mirasol PRT treatment is a pathogen reduction protocol that is based on the inactivation of nucleic acid replication after exposure to riboflavin and light and was tested for its ability to inactivate nucleated WBC function.

STUDY DESIGN AND METHODS:  Sets of paired WBCs from different donors who either had received Mirasol treatment or were untreated were tested for their ability to be activated in response to phorbol myristic acetate (PMA); to proliferate in response to stimuli including phytohemagglutinin PHA, anti‐CD3+ anti‐CD28, or allogeneic stimulator cells; to stimulate proliferation by allogeneic responder cells; and to produce cytokines in response to lipopolysaccharide (LPS) and anti‐CD3+ anti‐CD28.

RESULTS:  Although Mirasol PRT treatment did not significantly change the distribution of human lymphocyte subpopulations, there were significant functional changes. Mirasol PRT treatment inhibited activation in response to PMA and completely inhibited proliferation in response to PHA, anti‐CD3+ anti‐CD28, or allogeneic stimulator cells. Mirasol PRT treatment also prevented the cells’ ability to act as antigen‐presenting cells and the ability to produce cytokines in response to stimuli such as LPS or anti‐CD3+ anti‐CD28.

CONCLUSIONS:  Mirasol PRT treatment is able to functionally inactivate WBCs in blood products along with inactivating pathogens and should prevent immunological consequences resulting from the presence of WBCs in blood products.
The effect of whole‐blood storage time on the number of white cells and platelets in whole blood and in white cell–reduced red cells
Authors: Van Der Meer Pieter F. , De Wildt‐Eggen Janny
Published: February 2006

BACKGROUND:  Whole blood (WB) can be stored for some time before it is processed into components. After introduction of universal white cell (WBC) reduction, it was observed that longer WB storage was associated with more residual WBCs in the WBC‐reduced red cells (RBCs). Also, weak propidium iodide (PI)‐positive events were observed in the flow cytometric WBC counting method, presumably WBC fragments. The effect of storage time on the composition of WB and subsequently prepared WBC‐reduced RBCs was studied.

STUDY DESIGN AND METHODS:  WB was collected in bottom‐and‐top collection systems with inline filters, obtained from Baxter, Fresenius, or MacoPharma. Units were stored at room temperature and separated into components in 4‐hour intervals between 4 and 24 hours after collection. RBCs were WBC‐reduced by inline filtration (approx. 50/group).

RESULTS:  Platelet (PLT) counts were lower in WB stored for 4 to 8 hours compared to 20 to 24 hours (mean ± SD): 79 ± 31 versus 102 ± 30 for Baxter (p  < 0.01); 91 ± 31 versus 101 ± 35 for Fresenius (not significant); and 73 ± 47 versus 97 ± 31 (all × 109 per unit) for MacoPharma (p < 0.01), respectively. The median residual WBC counts in WBC‐reduced RBCs for WB stored for 4 to 8 and 20 to 24 hours were 0.03 versus 0.17 for Baxter (p < 0.001), 0.00 versus 0.06 for Fresenius (p < 0.001), and 0.13 versus 0.26 (all × 106 per unit) for MacoPharma (not significant), respectively. All WBC‐reduced RBCs contained fewer than 5 × 106 WBCs per unit. A longer storage time of WB was associated with more weak PI‐positive events, irrespective of the filter.

CONCLUSION:  Longer storage of WB before processing results in counting higher numbers of PLTs in WB, higher numbers of WBCs in WBC‐reduced RBCs, and more weak PI‐positive events.
Introducing Fear of Crime to Risk Research
Authors: Jackson Jonathan
Published: February 2006

This article introduces the fear of crime to risk research, noting a number of areas for future interdisciplinary study. First, the article analyzes both the career of the concept of fear of crime and the politics of fear. Second, it considers research and theory on the psychology of risk, particularly the interplay between emotion and cognition, and what might be called the risk as image perspective. Third, the article speculates how people learn about risk and suggests how to customize a social amplification of risk framework to fear of crime. Finally, the article advances the argument that fear of crime may be an individual response to community social order and a generalized attitude toward the moral trajectory of society. Each of these areas of discussion has implications for future theoretical developments within risk research; each highlights how risk research can contribute to the social scientific understanding of an important issue of the day.
Melatonin effect on bone metabolism in rats treated with methylprednisolone
Authors: Ladizesky Marta G. , Boggio Verónica , Cutrera Rodolfo A. , Mondelo Nélida , Mastaglia Silvina , Somoza Julia , Cardinali Daniel P.
Published: February 2006

Abstract:  The present study was undertaken to examine the effect of melatonin (25 μg/mL of drinking water, about 500 μg/day) on a 10‐wk long treatment of male rats with methylprednisolone (5 mg/kg s.c., 5 days/wk). Bone densitometry and mechanical properties, calcemia, phosphatemia and serum bone alkaline phosphatase activity and C‐telopeptide fragments of collagen type I (CTX) were measured. Both melatonin and methylprednisolone decreased significantly body weight (BW) and the combination of both treatments resulted in the lowest BW values found. Consequently, all results were analyzed with BW as a covariate. Densitometrically, methylprednisolone augmented bone mineral content (BMC), bone area (BA) and bone mineral density (BMD) in the entire skeleton, BMC in cortical bone, and BMC and BMD in trabecular bone. Melatonin increased BMC and BA in whole skeleton and BMC and BMD in trabecular bone. For BMC and BA of whole skeleton, BMC of cortical bone, and BMC and BMD of trabecular bone, the combination of glucocorticoids and melatonin resulted in the highest values observed. Femoral weight of rats receiving methylprednisolone or melatonin increased significantly and both treatments summated to achieve the greatest effect. In femoral biomechanical testing, methylprednisolone augmented ultimate load and work to failure significantly. Rats receiving the combined treatment of methylprednisolone and melatonin showed the highest values of work to failure. The circulating levels of CTX, an index of bone resorption, decreased after methylprednisolone or melatonin, both treatments summating to achieve the lowest CTX values found. Serum calcium increased after methylprednisolone and serum phosphorus decreased after treatment with methylprednisolone or melatonin while serum bone alkaline phosphatase levels remained unchanged. The results are compatible with the view that low doses of methylprednisolone or melatonin decrease bone resorption and have a bone‐protecting effect.
Central nervous system metastases in women with HER‐2 positive metastatic breast cancer after treatment with trastuzumab
Authors: DAWSON Sarah‐Jane , RANIERI Nadia F , SNYDER Raymond D , McLACHLAN Sue‐Anne , BURNS William I , NEWNHAM Genni M , FRANCIS Prudence A , DOWLING Anthony J
Published: February 2006

Background: 
Historically, central nervous system (CNS) metastases have been reported to occur in 10–16% of women with metastatic breast cancer (MBC) with a median survival of less than 1 year after diagnosis of CNS disease. A higher rate of CNS metastases has been described in women with metastatic breast cancer (MBC) over‐expressing HER‐2 who receive trastuzumab therapy.

Aims:  The aim of this study was to examine the frequency of and potential risk factors for CNS metastases in these women. Our a priori hypotheses were that in MBC patients treated with trastuzumab, CNS metastases occurred (i) more frequently than historical controls, and (ii) in women with controlled systemic disease.

Methods:  A retrospective cohort study of 28 consecutive patients with MBC over‐expressing HER‐2 and treated with trastuzumab and chemotherapy was performed.

Results:  A total of 22/25 (88%) patients who initially responded to trastuzumab had progressed within a median of 11.2 months after starting trastuzumab therapy. Central nervous system metastases occurred in 11/28 (39%) patients and the remaining 11 patients had progressed elsewhere. At diagnosis of CNS metastases, 9/11 (82%) had controlled systemic disease (CR = 2, PR = 6, SD = 1). There were trends for patients with CNS metastases to have greater than one site of metastatic disease at the commencement of trastuzumab therapy (P = 0.06), and to be hormone receptor negative at initial diagnosis (P = 0.14). The median time to diagnosis of CNS metastases after the commencement of trastuzumab therapy was 12 months (range 6–19 months). The median survival after diagnosis of CNS metastases was 12 months (range 2–22 months).

Conclusions:  This study demonstrates a high rate of CNS metastases (39%) in HER‐2 positive MBC patients treated with trastuzumab. At CNS metastases most patients had controlled systemic disease and the median survival after CNS relapse was 1 year. We suggest aggressive management of CNS disease in this population. Additional strategies to decrease the incidence of CNS metastases in these patients may include prophylactic whole brain irradiation and the development of novel pharmacological agents with successful CNS penetration.
Apoptosis occurs early in the basal layer of the oral mucosa following cancer chemotherapy
Authors: GIBSON Rachel J , CUMMINS Adrian G , BOWEN Joanne M , LOGAN Richard M , HEALEY Tabitha , KEEFE Dorothy M
Published: February 2006

Background: Oral mucositis, a debilitating side‐effect of chemotherapy, is difficult to prevent or treat. The aim of this study was to characterize the histological and ultrastructural change in the human oral mucosa following cytotoxic chemotherapy.

Methods: Oral buccal mucosa biopsies were taken from four volunteers and 20 cancer patients. Each patient had one biopsy prior to chemotherapy and a second biopsy at varying intervals after chemotherapy. Biopsies were assessed histologically and ultrastructurally.

Results: Apoptosis increased in the basal layer in the first 3 days after chemotherapy, began to decline at 6 days, but never returned to levels of volunteers by 11 days after treatment. Ultrastructural changes included increased intercellular fibres in basal layer cells, cytoplasmic vacuolation, loss of membrane contact with neighboring cells, multinucleation of suprabasal cells and loss of cellular cytoplasm. These changes persisted in prechemotherapy biopsies in patients who had prior chemotherapy.

Conclusions: Apoptosis occurs early, and persists in the basal layer of the buccal mucosa after chemotherapy. Ultrastructural changes were present and remained up to 11 days after chemotherapy.
Bone marrow involvement in small cell lung cancer: Prognostic significance and correlation with hematological and biochemical parameters
Authors: OZKAN Metin , ESER Bulent , ER Ozlem , COSKUN H. Senol , OZTURK Ahmet , SARI Ismail , CANOZ Ozlem , ALTINBAS Mustafa
Published: February 2006

The more metastatic sites and bone marrow metastasis in small cell lung cancer (SCLC), the worse the prognosis. Diagnosing the bone marrow invasion at the beginning of the therapy is important for determining of the prognosis and planning the treatment. Abnormalities of some blood parameters may help to estimate the extent of bone marrow invasion by cancer cells. In this retrospective review, the changes in routine laboratory tests that may indicate bone marrow invasion, the predictive values of these tests, and the prognostic importance of bone marrow invasion were evaluated in SCLC patients who were being followed up according to a protocol. One hundred and forty‐four patients with SCLC were enrolled in this study. Retrospectively, it was evaluated that 25 (17.4%) of the patients had bone marrow metastasis. According to univariate analysis, there was a significant difference between hemoglobin, white blood cell count, platelet count, lactate dehydrogenase, alkaline phosphatase and uric acid of the patients with and without bone marrow involvement. Among the biochemical parameters, the elevated LDH and AP had the highest sensitivity and specificity as indicators of bone marrow invasion (0.80–0.82 and 0.84–0.78, respectively). The median overall survival of extensive‐stage disease with and without bone marrow metastasis were 4.0 ± 1.0 months (95% CI 2.2–5.7) and 7.0 ± 1.2 months (95% CI 4.7–9.3), respectively (P = 0.03). Bone marrow metastasis was found to be an indicator of a bad prognosis. Bone marrow biopsy, that is an invasive procedure, can be performed on selected patients who have changes of routine laboratory tests suggesting bone marrow invasion.
A shortcut to seasonal design rainfall estimates in the UK
Authors: Kjeldsen T. R. , Prudhomme C. , Svensson C. , Stewart E. J.
Published: February 2006

The depth–duration–frequency (DDF) model developed as part of the Flood Estimation Handbook (FEH) enables estimates of design rainfall to be made at any location in the UK. This study presents a shortcut method for estimating seasonal design rainfall for a summer and winter season, respectively, using a simple seasonal correction factor in combination with the FEH DDF estimate of design rainfall. The seasonal correction factors were derived for the summer and winter season for a range of durations. The observed correction factors were linked to standard average annual rainfall available from the FEH CD‐ROM, thereby enabling the use of this method at any location in the UK. The results obtained in this study are shown to correspond well to the summary statistics on seasonal rainfall presented in the Flood Studies Report.
Correlation Moment
Analysis and the Time Dependence of Coherence in Systems Described by Nonlinear Partial Differential
Equations
Authors: Belmont M.
R.
Published: February 2006

The work presented introduces correlation moment analysis. This technique can be employed to explore the growth of determinism from stochastic initial conditions in physical systems described by non-linear partial differential equations (PDEs) and is also applicable to wholly deterministic situations. Correlation moment analysis allows the analytic determination of the time dependence of the spatial moments of the solutions of certain types of non-linear partial differential equations. These moments provide measures of the growth of processes defined by the PDE, furthermore the results are obtained without requiring explicit solution of the PDE. The development is presented via case studies of the linear diffusion equation and the non-linear Kortweg de-Vries equation which indicate strategies for exploiting the various properties of correlation moments developed in the text. In addition, a variety of results have been developed which show how various classes of terms in PDEs affect the structure of a sequence of correlation moment equations. This allows results to be obtained about the behavior of the PDE solution, in particular how the presence of certain types of terms affects integral measures of the solution. It is also demonstrated that correlation moments provide a very simple, natural approach to determining certain subsets of conserved quantities associated with the PDEs.
Transient Response of
Transversely Isotropic Composite Plates to a Point
Source
Authors: Mahmoud A. , Shah A.
H. , Dong S.
B.
Published: February 2006

In this paper, transient three-dimensional response of a transversely isotropic composite plate to a time varying point load is efficiently computed by reducing the elastodynamic equation through integral and coordinate transformations to a series of two-dimensional problems, each associated with a plane wave along a given direction in the plate. Discrete equations of a semi-analytical finite element model are solved for the thickness profile eigendata at a given frequency. Three-dimensional steady state responses in the wave number domain are formed by summing contributions from eigenmodes over propagation directions. The transient response is obtained by a numerical integration of inverse Fourier time transform of these steady state responses. Present results showed good agreement with data reported in the literature and confirmed previously observed phenomena.
The Mode III Interface Crack in Piezo-Electro-Magneto-Elastic Dissimilar Bimaterials
Authors: Li R. , Kardomateas G. A.
Published: February 2006

The mode III interface crack problem is investigated for dissimilar piezo-electro-magneto-elastic bimaterial media, taking the electro-magnetic field inside the crack into account. Closed form solutions are derived for impermeable and permeable cracks. The conventional singularity of r−1∕2 is found for the fields at the distance r ahead of the interface crack tip. Expressions for extended crack tip stress fields and crack opening displacements (ECODs) are derived explicitly, and so are some fracture parameters, such as extended stress intensity factors (ESIFs) and energy release rate (G) for dissimilar bimaterials. An approach called the “energy method,” finding the stationary point of the saddle surface of energy release rate with respect to the electro-magnetic field inside the crack, is proposed. By this method, the components of the induced electro-magnetic field inside the crack are determined, and the results are in exact agreement with those in the literature if the two constituents of the bimaterial media are identical. The effects from mechanical and electro-magnetic property mismatches, such as differences in the stiffness, electric permittivity and magnetic permeability, between the two constituents of the bimedia on the mode III interface crack propagation are illustrated by numerical simulations. The results show that the applied electric and magnetic loading usually retard the growth of the interface crack and the directions of the combined mechanical, electric, and magnetic loading have a significant influence on the mode III interface crack propagation.
Size Effects on
Cavitation Instabilities
Authors: Niordson Christian
F. , Tvergaard Viggo
Published: February 2006

In metal-ceramic systems the constraint on plastic flow leads to so high stress triaxialities that cavitation instabilities may occur. If the void radius is on the order of magnitude of a characteristic length for the metal, the rate of void growth is reduced, and the possibility of unstable cavity growth is here analyzed for such cases. A finite strain generalization of a higher order strain gradient plasticity theory is applied for a power-law hardening material, and the numerical analyses are carried out for an axisymmetric unit cell containing a spherical void. In the range of high stress triaxiality, where cavitation instabilities are predicted by conventional plasticity theory, such instabilities are also found for the nonlocal theory, but the effects of gradient hardening delay the onset of the instability. Furthermore, in some cases the cavitation stress reaches a maximum and then decays as the void grows to a size well above the characteristic material length.
Control of Bending
Vibrations Within Subdomains of Thin Plates—Part II: Piezoelectric Actuation and Approximate
Solution
Authors: Krommer Michael , Varadan Vasundara
V.
Published: February 2006

In the first part of this paper, we presented the theoretical basics of a new method to control the bending motion of a subdomain of a thin plate. We used continuously distributed sources of self-stress, applied within the subdomain, to exactly achieve the desired result. From a practical point of view, continuously distributed self-stresses cannot be realized. Therefore, we discuss the application of discretely placed piezoelectric actuators to approximate the continuous distribution in this part. Using piezoelectric patch actuators requires the consideration of electrostatic equations as well. However, if the patches are relatively thin, the electromechanical coupling can be incorporated by means of piezoelastic (instead of elastic) stiffness (piezoelastically stiffended elastic constants). The placement of the patches is based on the discretization of the exact continuous distribution by means of piece-wise constant functions. These are calculated from a convolution integral representing the deviation of the bending motion in the controlled case from the desired one. A proper choice of test loadings allows us to eliminate representative mechanical quantities exactly and to make the resulting bending motion to match the desired one very closely; hence, to find a suboptimal approximate solution. In Part I of this paper we presented exact solutions for the axisymmetric bending of circular plates; it is also considered in Part II. For axisymmetric bending, only the radial coordinate is discretized. Hence, ring-shaped piezoelectric patch actuators are considered in this paper.
Calendering Pseudoplastic and Viscoplastic Fluids With Slip at the Roll Surface
Authors: Mitsoulis E. , Sofou S.
Published: February 2006

The lubrication approximation theory (LAT) is used to provide numerical results for calendering a sheet from an infinite reservoir. The Herschel–Bulkley model of viscoplasticity is employed, which reduces with appropriate modifications to the Bingham, power-law, and Newtonian models. A dimensionless slip coefficient is introduced to account for the case of slip at the roll surfaces. The results give the final sheet thickness as a function of the dimensionless power-law index (in the case of pseudoplasticity), the Bingham number or the dimensionless yield stress calculated at the nip (in the case of viscoplasticity), and the dimensionless slip coefficient in both cases. Integrated quantities of engineering interest are also calculated. These include the maximum pressure, the roll-separating force, and the power input to the rolls. Decreasing the power-law index or increasing the dimensionless yield stress lead to excess sheet thickness over the thickness at the nip. All engineering quantities calculated in dimensionless form increase substantially with the departure from the Newtonian values. The presence of slip decreases pressure and the engineering quantities and increases the domain in all cases.
Suppression of Boiling Flow Oscillations in Parallel Microchannels by Inlet Restrictors
Authors: Koşar Ali , Kuo Chih-Jung , Peles Yoav
Published: February 2006

Geometrical effects of MEMS-based microfabricated inlet orifices on the suppression of parallel channel and upstream compressible volume instabilities commonly exhibited during flow boiling in parallel microchannels have been investigated. The heat fluxes at the onset of unstable boiling have been obtained over effective heat fluxes ranging from 9 to 614W∕cm2 and mass fluxes from 115to389kg∕m2s. A dimensionless parameter M, which accounts for the pressure drop increase imposed by the inlet restrictors, has been used to correlate the extent of flow instability suppression. It has been shown that the onset of unstable boiling asymptotically increases with M. At sufficiently high M values, parallel channels and upstream compressible volume instabilities are completely eradicated although it gives way to another instability to develop, namely, the critical heat flux conditions. A correlation has been developed in terms of M to predict the conditions leading to unstable boiling.
Staphylococcal Cassette Chromosome
mec
(SCC
mec
) Typing of Methicillin-Resistant
Staphylococcus aureus
Strains Isolated in 11 Asian Countries: a Proposal for a New Nomenclature for SCC
mec
Elements
Authors: Chongtrakool Piriyaporn , Ito Teruyo , Ma Xiao Xue , Kondo Yoko , Trakulsomboon Suwanna , Tiensasitorn Chuntima , Jamklang Mantana , Chavalit Tavinun , Song Jae-Hoon , Hiramatsu Keiichi
Published: February 2006

A description of staphylococcal cassette chromosome
mec
(SCC
mec
) elements carried by 615 methicillin-resistant
Staphylococcus aureus
(MRSA) strains isolated in 11 Asian countries is reported, and a novel nomenclatural system based on their structures is proposed. The 615 strains were classified as type 3A (370 strains), type 2A (207 strains), type 2B (32 strains), type 1B (1 strain), and nontypeable (5 strains). The previously reported type III SCC
mec
(DDBJ/EMBL/GenBank accession no. AB037671) carried by the MRSA strain 85/2082 was ascertained to be composed of two SCC elements, type 3A SCC
mec
and SCC
mercury
. PCR analysis indicated that 310 of 370 type 3A SCC
mec
strains carried both SCC elements. These strains were prevalent in eight countries: Thailand, Sri Lanka, Indonesia, Vietnam, Philippines, Saudi Arabia, India, and Singapore. The remaining 60 type 3A SCC
mec
strains differed with respect to the left extremity polymorphism or to the presence of
ccrC
. Among these, two were identified as carrying only type 3A SCC
mec
elements, but their left extremities differed. Type 2A SCC
mec
strains predominated in Korea and Japan, although the frequency of the presence of
ant
(
4
′)-1 gene downstream of
mecA
varied (53% for Korean strains; 93% for Japanese strains). Various SCC
mec
elements were identified in the tested strains, and limited numbers were identified by their multilocus sequence typing genotypes. These data suggest that numerous MRSA clones are disseminated in Asian hospitals, and these consist of minor clones that are presumed to have arisen locally and major clones that are presumed to have been introduced from other countries.
Transfer of Vancomycin Resistance Transposon Tn
1549
from
Clostridium symbiosum
to
Enterococcus
spp. in the Gut of Gnotobiotic Mice
Authors: Launay Aline , Ballard Susan A. , Johnson Paul D. R. , Grayson M. Lindsay , Lambert Thierry
Published: February 2006

The vancomycin resistance
vanB2
gene cluster is disseminated worldwide and has been found in phylogenetically remote bacterial genera. The
vanB2
operon is part of conjugative transposons Tn
1549
/Tn
5382
, but conjugative transposition of these elements has not been demonstrated. We have obtained transfer of a Tn
1549
-like element (referred to herein as “Tn
1549
-like”) from
Clostridium symbiosum
MLG101 to
Enterococcus faecium
64/3 and
Enterococcus faecalis
JH2-2 in the digestive tract of gnotobiotic mice and to
E. faecium
64/3 in vitro. Retransfer of Tn
1549
-like from an
E. faecium
transconjugant also containing Tn
916
to
E. faecium
BM77 was obtained in vitro, albeit at a very low frequency. Transfer efficiency was found to be both donor and recipient dependent. Pulsed-field gel electrophoresis analysis of total SmaI-digested DNA of 48 transconjugants indicated in 27 instances the acquisition of ca. 34 kb of DNA. Two transconjugants harbored two copies of the transposon. Sequencing of the flanking regions of Tn
1549
-like in 48 transconjugants revealed 29 integration events in 26 loci in the
E. faecium
genome, and two hot spots for insertion were identified. Integration of the transposon was associated with the acquisition of 5 (
n
= 18) or 6 (
n
= 7) bp of donor DNA or with 5-bp duplications of target DNA in the remaining transconjugants. These data demonstrate functionality of the Tn
1549
-like element and attest that the transfer of the
vanB
operon between enterococci and human commensal anaerobes occurs in the intestinal environment.
Activities of Telithromycin, Erythromycin, Fluoroquinolones, and Doxycycline against
Campylobacter
Strains Isolated from Finnish Subjects
Authors: Schönberg-Norio Daniela , Hänninen Marja-Liisa , Katila Marja-Leena , Kaukoranta Suvi-Sirkku , Koskela Markku , Eerola Erkki , Uksila Jaakko , Pajarre Sini , Rautelin Hilpi
Published: February 2006

The in vitro susceptibilities of 478
Campylobacter jejuni
and
Campylobacter coli
strains isolated from Finnish subjects during 2002 to 2004 were determined. Susceptibility to erythromycin remained high, and telithromycin did not offer any advantage over erythromycin. Reduced susceptibilities to fluoroquinolones and doxycycline were detected almost exclusively among isolates of foreign origin.
Staphylococcus
Efflux
msr
(A) Gene Characterized in
Streptococcus
,
Enterococcus
,
Corynebacterium
, and
Pseudomonas
Isolates
Authors: Ojo Kayode K. , Striplin Megan J. , Ulep Catherine C. , Close Natasha S. , Zittle Jennifer , Luis Henrique , Bernardo Mario , Leitao Jorge , Roberts Marilyn C.
Published: February 2006

The staphylococcal
msr
(A) gene, coding for a macrolide efflux protein, was identified in three new gram-positive genera and one gram-negative genus. These
msr
(A) genes shared 99 to 100% identity with each other and the staphylococcal gene. This study demonstrates that the
msr
(A) gene has a wider host range than previously reported.
In Vitro Activity of Novel Rifamycins against Rifamycin-Resistant
Staphylococcus aureus
Authors: Murphy Christopher K. , Mullin Steve , Osburne Marcia S. , van Duzer John , Siedlecki Jim , Yu Xiang , Kerstein Kathy , Cynamon Michael , Rothstein David M.
Published: February 2006

We describe novel rifamycin derivatives (new chemical entities [NCEs]) that retain significant activity against a comprehensive collection of
Staphylococcus aureus
strains that are resistant to rifamycins. This collection of resistant strains contains 21 of the 26 known single-amino-acid alterations in RpoB, the target of rifamycins. Some NCEs also demonstrated a lower frequency of resistance development than rifampin and rifalazil in
S. aureus
as measured in a resistance emergence test. When assayed for activity against the strongest rifamycin-resistant mutants, several NCEs had MICs of 2 μg/ml, in contrast to MICs of rifampin and rifalazil, which were 512 μg/ml for the same strains. The properties of these NCEs therefore demonstrate a significant improvement over those of earlier rifamycins, which have been limited primarily to combination therapy due to resistance development, and suggest a potential use of these NCEs for monotherapy in several clinical indications.
Pharmacodynamic Evaluation of the Intracellular Activities of Antibiotics against
Staphylococcus aureus
in a Model of THP-1 Macrophages
Authors: Barcia-Macay Maritza , Seral Cristina , Mingeot-Leclercq Marie-Paule , Tulkens Paul M. , Van Bambeke Françoise
Published: February 2006

The pharmacodynamic properties governing the activities of antibiotics against intracellular
Staphylococcus aureus
are still largely undetermined. Sixteen antibiotics of seven different pharmacological classes (azithromycin and telithromycin [macrolides]; gentamicin [an aminoglycoside]; linezolid [an oxazolidinone]; penicillin V, nafcillin, ampicillin, and oxacillin [β-lactams]; teicoplanin, vancomycin, and oritavancin [glycopeptides]; rifampin [an ansamycin]; and ciprofloxacin, levofloxacin, garenoxacin, and moxifloxacin [quinolones]) have been examined for their activities against
S. aureus
(ATCC 25923) in human THP-1 macrophages (intracellular) versus that in culture medium (extracellular) by using a 0- to 24-h exposure time and a wide range of extracellular concentrations (including the range of the MIC to the maximum concentration in serum [
C
max
; total drug] of humans). All molecules except the macrolides caused a net reduction in bacterial counts that was time and concentration/MIC ratio dependent (four molecules tested in detail [gentamicin, oxacillin, moxifloxacin, and oritavancin] showed typical sigmoidal dose-response curves at 24 h). Maximal intracellular activities remained consistently lower than extracellular activities, irrespective of the level of drug accumulation and of the pharmacological class. Relative potencies (50% effective concentration or at a fixed extracellular concentration/MIC ratio) were also decreased, but to different extents. At an extracellular concentration corresponding to their
C
max
s (total drug) in humans, only oxacillin, levofloxacin, garenoxacin, moxifloxacin, and oritavancin had truly intracellular bactericidal effects (2-log decrease or more, as defined by the Clinical and Laboratory Standards Institute guidelines). The intracellular activities of antibiotics against
S. aureus
(i) are critically dependent upon their extracellular concentrations and the duration of cell exposure (within the 0- to 24-h time frame) to antibiotics and (ii) are always lower than those that can be observed extracellularly. This model may help in rationalizing the choice of antibiotic for the treatment of
S. aureus
intracellular infections.
Telavancin versus Standard Therapy for Treatment of Complicated Skin and Skin Structure Infections Caused by Gram-Positive Bacteria: FAST 2 Study
Authors: Stryjewski Martin E. , Chu Vivian H. , O'Riordan William D. , Warren Brian L. , Dunbar Lala M. , Young David M. , Vallée Marc , Fowler Vance G. , Morganroth Joel , Barriere Steven L. , Kitt Michael M. , Corey G. Ralph
Published: February 2006

Telavancin is a bactericidal lipoglycopeptide with a multifunctional mechanism of action. We conducted a randomized, double blind, active-control phase II trial. Patients ≥18 years of age with complicated skin and skin structure infections caused by suspected or confirmed gram-positive organisms were randomized to receive either telavancin at 10 mg/kg intravenously every 24 h (q24h) or standard therapy (antistaphylococcal penicillin at 2 g q6h or vancomycin at 1 g q12h). A total of 195 patients were randomized and received at least one dose of study medication. Clinical success rates were similar in all analysis populations at test of cure. In microbiologically evaluable patients with
Staphylococcus aureus
at baseline (
n
= 91), 96% of the telavancin group and 90% of the standard-therapy group were cured. Among patients with methicillin-resistant
S. aureus
(MRSA) at baseline (
n
= 45), clinical cure rates were also 96% for telavancin and 90% for standard therapy. Microbiologic eradication in patients with
S. aureus
infection was better with telavancin compared to standard therapy (92% versus 78%,
P
= 0.07) and significantly better in patients with MRSA (92% versus 68%;
P
= 0.04). Therapy was discontinued for an adverse event (AE) in 6% and 3% of the patients receiving telavancin and standard therapy, respectively. Except for two cases of rash in the telavancin group, these AEs were similar in type and severity in the two groups. The overall incidences and severities of AEs and laboratory abnormalities were similar between the two groups. These data support the ongoing studies assessing the efficacy and safety of telavancin in the treatment of serious gram-positive infections, particularly involving MRSA.