bluuebunny/crossref_metadata_2025 huggingface dataset:
Postnatal Mental Health of Women Giving Birth in Australia 2002–2004: Findings from the Beyondblue National Postnatal Depression Program
Authors: Buist Anne E. , Austin Marie-Paule V. , Hayes Barbara A. , Speelman Craig , Bilszta Justin L.C. , Gemmill Alan W. , Brooks Janette , Ellwood David , Milgrom Jeannette
Published: December 2007

Objectives: To describe the postnatal mental health status of women giving birth in Australia 2002–2004 at 6–8 weeks postpartum.

Method: Women were recruited from 43 health services across Australia. Women completed a demographic questionnaire and an Edinburgh Postnatal Depression Scale (EPDS) in pregnancy; the latter was repeated at 6–8 weeks following childbirth.

Results: A total of 12 361 postnatal women (53.8% of all postnatal women surveyed) completed questionnaires as part of a depression screening programme; 15.5% of women screened had a postnatal EPDS>9 and 7.5% of women had an EPDS>12 at 6–8 weeks following childbirth. There was significant variation between States in the percentage of women scoring as being potentially depressed. The highest percentage of women scoring EPDS>12 were in Queensland and South Australia (both 10.2%) while Western Australia had the lowest point prevalence (5.6%). Women recruited from private health services in Western Australia had a significantly lower prevalence of elevated EPDS scores than those women recruited from the public health service (EPDS >12: 3.6% vs 6.4%, p=0.026); differences in the prevalence of elevated EPDS scores were not significant between public and private in Australian Capital Territory (EPDS>12: 7.6% vs 5.8%, p=0.48), where income and education was significantly higher than other States for both groups.

Conclusions: Postnatal depressive symptoms affect a significant number of women giving birth in Australia, and the point prevalence on the EPDS may be higher for women in the public sector, associated with lower incomes and educational levels. Maternity services – particularly those serving women with these risk factors – need to consider how they identify and manage the emotional health needs of women in their care. Specific State-related issues, such as availability of specialist perinatal mental health services and liaison between treating health professionals, also need to be considered.
Withdrawal Symptoms Do Not Predict Relapse among Subjects Treated for Cannabis Dependence
Authors: Arendt Mikkel , Rosenberg Raben , Foldager Leslie , Sher Leo , Munk‐Jørgensen Povl
Published: December 2007

This is the first follow‐up study on the association between cannabis withdrawal symptoms and risk of relapse to cannabis use. Withdrawal symptoms were assessed in 36 subjects seeking treatment for cannabis dependence. All were free of other substance use or alcohol abuse in the month before abstinence from cannabis. Follow‐up was performed 26±4 months later, and at this point, the withdrawal symptoms were re‐assessed. The following symptoms were significantly elevated after abstinence compared with follow‐up: irritability, anger, depression, restlessness, craving, sleep problems, strange dreams, increased appetite, violent outbursts, sweating, hot flashes, chills, and shakiness. This offers further validation of a cannabis withdrawal syndrome. Average withdrawal scores at baseline did not differ with gender, age, treatment type, extent of cannabis use, or a lifetime history of anxiety or affective disorders. Withdrawal scores at baseline did not predict relapse during follow‐up.
Impact of Substance Abuse Treatment on Arrests among Opiate Users in Washington State
Authors: Campbell Kevin M , Deck Dennis , Krupski Antoinette
Published: December 2007

Administrative data from Washington State's Division of Alcohol and Substance Abuse drive this three‐year prospective study of the impact of substance abuse treatment on arrests among 12,962 opiate users receiving publicly funded substance abuse services. Using survival analysis, the risk of arrest among opiate users who receive substance abuse treatment is compared to those who do not receive treatment. Propensity scores control for client characteristics associated with admission to substance abuse treatment. Overall, a reduction in the risk of arrest was found among subjects in treatment (Hazard Ratio = 0.59–0.78, p < .05) and subjects successfully completing treatment (Hazard Ratio = 0.75, p < .05). Risk of arrest was elevated among those with a negative outcome to treatment (Hazard Ratio = 1.23, p < .05).
Factors Associated with Altered Pharmacokinetics in Substance Users and Non‐Substance Users Receiving Lopinavir and Atazanavir
Authors: Higgins Niamh , Zingman Barry S. , Slish Judianne , Reichman Richard C. , Fischl Margaret A. , Gripshover Barbara , Tooley Kelly , Boston Naomi , Forrest Alan , Brazeau Dan , Catanzaro Linda M. , DiFrancesco Robin , Lliguicota Francesco , Ma Qing , Morse Gene D.
Published: December 2007

Substance use is highly prevalent in HIV‐infected individuals in the United States, and clinical management is complicated by the need for antiretroviral treatment, addiction therapy, variable medication adherence, and co‐morbidities. The interrelation between HIV and substance use prompted our investigation to examine substance use and self‐reported medication adherence in patients receiving the HIV‐1 protease inhibitors, atazanavir (ATV) or lopinavir (LPV). ATV and LPV pharmacokinetics were determined by measuring plasma concentrations in subjects with active substance use (SU group) or with no active substance use (NSU group). No difference in adherence was observed between groups (p > 0.05). The mean SU ATV trough was 0.550±0.45 μg/mL; the mean NSU ATV trough was 0.780±0.590 μg/mL (p > 0.05). The mean SU LPV trough was 4.02±2.39 μg/mL; the mean NSU LPV trough was 6.67±0.910 μg/mL (p = 0.01). Co‐factors found to be associated with variation in ATV and LPV concentrations included concurrent methadone use, cigarette smoking, and substance use status. These data indicate that chronic HIV treatment may be assisted with plasma concentration monitoring to identify those patients who may require dosage modification and/or regimen adjustment in order to optimize antiretroviral effects.
Assembly reconciliation
Authors: Zimin Aleksey V. , Smith Douglas R. , Sutton Granger , Yorke James A.
Published: December 2007

Motivation: Many genomes are sequenced by a collaboration of several centers, and then each center produces an assembly using their own assembly software. The collaborators then pick the draft assembly that they judge to be the best and the information contained in the other assemblies is usually not used.

Methods: We have developed a technique that we call assembly reconciliation that can merge draft genome assemblies. It takes one draft assembly, detects apparent errors, and, when possible, patches the problem areas using pieces from alternative draft assemblies. It also closes gaps in places where one of the alternative assemblies has spanned the gap correctly.

Results: Using the Assembly Reconciliation technique, we produced reconciled assemblies of six Drosophila species in collaboration with Agencourt Bioscience and The J. Craig Venter Institute. These assemblies are now the official (CAF1) assemblies used for analysis. We also produced a reconciled assembly of Rhesus Macaque genome, and this assembly is available from our website http://www.genome.umd.edu.

Availability: The reconciliation software is available for download from http://www.genome.umd.edu/software.htm

Contact:  alekseyz@ipst.umd.edu
Thrombocytopenia in hydropic fetuses with parvovirus B19 infection: incidence, treatment and correlation with fetal B19 viral load
Authors: De Haan TR , Van Den Akker ESA , Porcelijn L , Oepkes D , Kroes ACM , Walther FJ
Published: December 2007

Objective  To examine (1) the incidence of fetal thrombocytopenia in hydropic fetuses with congenital B19 virus infection, (2) the effect of intrauterine platelet transfusions and (3) the correlation between fetal B19 viral load and severity of thrombocytopenia.

Design  Retrospective analysis of data from prospectively collected fetal blood samples.

Setting  Leiden University Medical Centre, the national centre for management of intrauterine fetal disease in the Netherlands.

Population  Thirty hydropic fetuses treated with intrauterine red blood cell and platelet transfusions for human B19 virus‐induced severe fetal anaemia and thrombocytopenia over a 10‐year period.

Methods  Fetal blood samples (n= 30) taken before and after intrauterine transfusion were investigated. No cases were excluded, and there was no loss to follow up.

Main outcome measures  Parameters recorded were gestational age, experienced fetal movements, gravidity and parity, severity of fetal hydrops, severity of fetal anaemia and thrombocytopenia and megakaryocyte and reticulocyte counts. Survival and procedure‐associated complications were documented. Quantitative B19 viral load measurements were performed on all fetal samples.

Results  Forty‐six percent of all hydropic fetuses showed severe thrombocytopenia. No antenatal intracerebral haemorrhage or procedure‐associated bleeding occurred. Overall, survival was 77%. Platelet counts increased following platelet transfusion and decreased significantly following red blood cell transfusion alone. No correlation was found between fetal viral loads and platelet counts.

Conclusion  Thrombocytopenia was frequently encountered in fetal B19V infection, but fetal bleeding complications were not noted. Absence of a direct relationship between fetal B19 viral load and platelet counts suggests a temporal dissociation between these findings. Dilutional thrombocytopenia is frequently seen in the fetus following red blood cell transfusion alone. The clinical significance of this phenomenon is unclear. The risk of fluid overload by fetal platelet transfusion in a severely hydropic fetus should be weighed against the low incidence of fetal bleeding complications.
X‐ray imaging using avalanche multiplication in amorphous selenium: Investigation of intrinsic avalanche noise
Authors: Hunt D. C. , Tanioka Kenkichi , Rowlands J. A.
Published: December 2007

The flat‐panel detector (FPD) is the state‐of‐the‐art detector for digital radiography. The FPD can acquire images in real‐time, has superior spatial resolution, and is free of the problems of x‐ray image intensifiers—veiling glare, pin‐cushion and magnetic distortion. However, FPDs suffer from poor signal to noise ratio performance at typical fluoroscopic exposure rates where the quantum noise is reduced to the point that it becomes comparable to the fixed electronic noise. It has been shown previously that avalanche multiplication gain in amorphous selenium can provide the necessary amplification to overcome the electronic noise of the FPD. Avalanche multiplication, however, comes with its own intrinsic contribution to the noise in the form of gain fluctuation noise. In this article a cascaded systems analysis is used to present a modified metric related to the detective quantum efficiency. The modified metric is used to study a diagnostic x‐ray imaging system in the presence of intrinsic avalanche multiplication noise independently from other noise sources, such as electronic noise. An indirect conversion imaging system is considered to make the study independent of other avalanche multiplication related noise sources, such as the fluctuations arising from the depth of x‐ray absorption. In this case all the avalanche events are initiated at the surface of the avalanche layer, and there are no fluctuations in the depth of absorption. Experiments on an indirect conversion x‐ray imaging system using avalanche multiplication in a layer of are also presented. The cascaded systems analysis shows that intrinsic noise of avalanche multiplication will not have any deleterious influence on detector performance at zero spatial frequency in x‐ray imaging provided the product of conversion gain, coupling efficiency, and optical quantum efficiency are much greater than a factor of 2. The experimental results show that avalanche multiplication in behaves as an intrinsic noise free avalanche multiplication, in accordance with our theory. Provided good coupling efficiency and high optical quantum efficiency are maintained, avalanche multiplication in has the potential to increase the gain and make negligible contribution to the noise, thereby improving the performance of indirect FPDs in fluoroscopy.
A patient‐specific respiratory model of anatomical motion for radiation treatment planning
Authors: Zhang Qinghui , Pevsner Alex , Hertanto Agung , Hu Yu‐Chi , Rosenzweig Kenneth E. , Ling C. Clifton , Mageras Gig S
Published: December 2007

The modeling of respiratory motion is important for a more accurate understanding and accounting of its effect on dose to cancers in the thorax and abdomen by radiotherapy. We have developed a model of respiration‐induced organ motion in the thorax without the commonly adopted assumption of repeatable breath cycles. The model describes the motion of a volume of interest within the patient based on a reference three‐dimensional (3D) image (at end expiration) and the diaphragm positions at different time points. The input data are respiration‐correlated CT (RCCT) images of patients treated for non‐small‐ cell lung cancer, consisting of 3D images, including the diaphragm positions, at ten phases of the respiratory cycle. A deformable image registration algorithm calculates the deformation field that maps each 3D image to the reference 3D image. A principal component analysis is performed to parameterize the 3D deformation field in terms of the diaphragm motion. We show that the first two principal components are adequate to accurately and completely describe the organ motion in the data of four patients. Artifacts in the RCCT images that commonly occur at the mid‐respiration states are reduced in the model‐generated images. Further validation of the model is demonstrated in the successful application of the parameterized 3D deformation field to RCCT data of the same patient but acquired several days later. We have developed a method for predicting respiration‐induced organ motion in patients that has potential for improving the accuracy of dose calculation in radiotherapy. Possible limitations of the model are cases where the correlation between lung tumor and diaphragm position is less reliable such as superiorly situated tumors and interfraction changes in tumor‐diaphragm correlation. The limited number of clinical cases examined suggests, but does not confirm, the model's applicability to a wide range of patients.
Adaptation of antenna profiles for control of MR guided hyperthermia (HT) in a hybrid MR‐HT system
Authors: Weihrauch Mirko , Wust Peter , Weiser Martin , Nadobny Jacek , Eisenhardt Steffen , Budach Volker , Gellermann Johanna
Published: December 2007

A combined numerical‐experimental iterative procedure, based on the Gauss‐Newton algorithm, has been developed for control of magnetic resonance (MR)‐guided hyperthermia (HT) applications in a hybrid MR‐HT system BSD 2000 3D‐MRI. In this MR‐HT system, composed of a 3‐D HT applicator Sigma‐Eye placed inside a tunnel‐type MR tomograph Siemens MAGNETOM Symphony , the temperature rise due to the HT radiation can be measured on‐line in three dimensions by use of the proton resonance frequency shift (PRFS) method. The basic idea of our iterative procedure is the improvement of the system's characterization by a step‐by‐step modification of the theoretical HT antenna profiles (electric fields radiated by single antennas). The adaptation of antenna profiles is efficient if the initial estimates are radiation fields calculated from a good a priori electromagnetic model. Throughout the iterative procedure, the calculated antenna fields (FDTD) are step‐by‐step modified by comparing the calculated and experimental data, the latter obtained using the PRFS method. The procedure has been experimentally tested on homogeneous and inhomogeneous phantoms. It is shown that only few comparison steps are necessary for obtaining a dramatic improvement of the general predictability and quality of the specific absorption rate (SAR) inside the MR‐HT hybrid system.
Computerized assessment of motion‐contaminated calcified plaques in cardiac multidetector CT
Authors: King Martin , Giger Maryellen L. , Suzuki Kenji , Bardo Dianna M. E. , Greenberg Brent , Lan Li , Pan Xiaochuan
Published: December 2007

An automated method for evaluating the image quality of calcified plaques with respect to motion artifacts in noncontrast‐enhanced cardiac computed tomography (CT) images is introduced. This method involves using linear regression (LR) and artificial neural network (ANN) regression models for predicting two patient‐specific, region‐of‐interest‐specific, reconstruction‐specific and temporal phase‐specific image quality indices. The first is a plaque motion index, which is derived from the actual trajectory of the calcified plaque and is represented on a continuous scale. The second is an assessability index, which reflects the degree to which a calcified plaque is affected by motion artifacts, and is represented on an ordinal five‐point scale. Two sets of assessability indices were provided independently by two radiologists experienced in evaluating cardiac CT images. Inputs for the regression models were selected from 12 features characterizing the dynamic, morphological, and intensity‐based properties of the calcified plaques. Whereas LR‐velocity (LR‐V) used only a single feature (three‐dimensional velocity), the LR‐multiple (LR‐M) and ANN regression models used the same subset of these 12 features selected through stepwise regression. The regression models were parameterized and evaluated using a database of simulated calcified plaque images from the dynamic NCAT phantom involving nine heart rate/multi‐sector gating combinations and 40 cardiac phases covering two cardiac cycles. Six calcified plaques were used for the plaque motion indices and three calcified plaques were used for both sets of assessability indices. In one configuration, images from the second cardiac cycle were used for feature selection and regression model parameterization, whereas images from the first cardiac cycle were used for testing. With this configuration, repeated measures concordance correlation coefficients (CCCs) and associated 95% confidence intervals for the LR‐V, LR‐M, and ANN were 0.817 [0.785, 0.848], 0.894 [0.869, 0.916], and 0.917 [0.892, 0.936] for the plaque motion indices. For the two sets of assessability indices, CCC values for the ANN model were 0.843 [0.791, 0.877] and 0.793 [0.747, 0.828]. These two CCC values were statistically greater than the CCC value of 0.689 [0.648, 0.727], which was obtained by comparing the two sets of assessability indices with each other. These preliminary results suggest that the variabilities of assessability indices provided by regression models can lie within the variabilities of the indices assigned by independent observers. Thus, the potential exists for using regression models and assessability indices for determining optimal phases for cardiac CT image interpretation.
A CAD system for nodule detection in low‐dose lung CTs based on region growing and a new active contour model
Authors: Bellotti R. , De Carlo F. , Gargano G. , Tangaro S. , Cascio D. , Catanzariti E. , Cerello P. , Cheran S. C. , Delogu P. , De Mitri I. , Fulcheri C. , Grosso D. , Retico A. , Squarcia S. , Tommasi E. , Golosio Bruno
Published: December 2007

A computer‐aided detection (CAD) system for the selection of lung nodules in computer tomography (CT) images is presented. The system is based on region growing (RG) algorithms and a new active contour model (ACM), implementing a local convex hull, able to draw the correct contour of the lung parenchyma and to include the pleural nodules. The CAD consists of three steps: (1) the lung parenchymal volume is segmented by means of a RG algorithm; the pleural nodules are included through the new ACM technique; (2) a RG algorithm is iteratively applied to the previously segmented volume in order to detect the candidate nodules; (3) a double‐threshold cut and a neural network are applied to reduce the false positives (FPs). After having set the parameters on a clinical CT, the system works on whole scans, without the need for any manual selection. The CT database was recorded at the Pisa center of the ITALUNG‐CT trial, the first Italian randomized controlled trial for the screening of the lung cancer. The detection rate of the system is with 6.6 FPs/CT on 15 CT scans (about 4700 sectional images) with 26 nodules: 15 internal and 11 pleural. A reduction to 2.47 FPs/CT is achieved at efficiency.
4D DMLC leaf sequencing to minimize organ at risk dose in moving anatomy
Authors: Papiez Lech , McMahon Ryan , Timmerman Robert
Published: December 2007

The most favorable treatment for moving body anatomy should aim at utilizing organ motion to minimize the dose to sensitive structures without compromising the dose delivered to the target. The solution of the problem of appropriate intensity redistribution over different phases of body motion is achievable in dynamic multileaf collimator (DMLC) intensity modulated radiation therapy delivery, due to the fact that multiple solutions are admissible for imposing the same intensity map over a moving target in this technique of irradiation. The realization of this type of delivery provides a treatment methodology that delivers treatment plans for moving patient anatomy that are superior to any treatments possible for static patient body anatomy. This paper is devoted to exploring this idea. To this end, a simple, though clinically realistic example is developed and presented that shows modified DMLC leaf motions that deliver a predetermined intensity to a moving target while reducing the dose delivered to organs at risk.
Region‐of‐interest image reconstruction in circular cone‐beam microCT
Authors: Cho Seungryong , Bian Junguo , Pelizzari Charles A. , Chen Chin‐Tu , He Tong‐Chuan , Pan Xiaochuan
Published: December 2007

Cone‐beam microcomputed tomography (microCT) is one of the most popular choices for small animal imaging which is becoming an important tool for studying animal models with transplanted diseases. Region‐of‐interest (ROI) imaging techniques in CT, which can reconstruct an ROI image from the projection data set of the ROI, can be used not only for reducing imaging‐radiation exposure to the subject and scatters to the detector but also for potentially increasing spatial resolution of the reconstructed images. Increasing spatial resolution in microCT images can facilitate improved accuracy in many assessment tasks. A method proposed previously for increasing CT image spatial resolution entails the exploitation of the geometric magnification in cone‐beam CT. Due to finite detector size, however, this method can lead to data truncation for a large geometric magnification. The Feldkamp‐Davis‐Kress (FDK) algorithm yields images with artifacts when truncated data are used, whereas the recently developed backprojection filtration (BPF) algorithm is capable of reconstructing ROI images without truncation artifacts from truncated cone‐beam data. We apply the BPF algorithm to reconstructing ROI images from truncated data of three different objects acquired by our circular cone‐beam microCT system. Reconstructed images by use of the FDK and BPF algorithms from both truncated and nontruncated cone‐beam data are compared. The results of the experimental studies demonstrate that, from certain truncated data, the BPF algorithm can reconstruct ROI images with quality comparable to that reconstructed from nontruncated data. In contrast, the FDK algorithm yields ROI images with truncation artifacts. Therefore, an implication of the studies is that, when truncated data are acquired with a configuration of a large geometric magnification, the BPF algorithm can be used for effective enhancement of the spatial resolution of a ROI image.
Monte Carlo investigation of breast intraoperative radiation therapy with metal attenuator plates
Authors: Martignano A. , Menegotti L. , Valentini A.
Published: December 2007

In intraoperative electron radiation therapy for breast cancer, attenuation plates are commonly used to protect organs at risk. These plates can be made of different materials, and the correct material (or combination of materials) has to be chosen in order to achieve the desired attenuation, while avoiding excessive backscattered radiation. The Monte Carlo method (BEAMnrcMP and DOSXYZnrcMP) has been used to characterize the electron beam generated by the setup (composed of a nondedicated linac and an applicator), and to simulate the percent depth dose (PDD) for plates of different materials. The beam has been characterized for nominal energies of 9 and 12 MeV. Several differently composed plates have been investigated: it was found, as expected, that the use of a plate presenting to the electron beam a high‐ material (i.e., lead) has to be avoided because of excessive backscatter (up to compared to the PDD without plate). On the other hand, the use of a single low‐ material (i.e., aluminum) in the plate can lead to an insufficient attenuation of the beam. The two‐layer plate (6 mm of Al plus 3 mm of Cu) used in S. Chiara Hospital has been found to attenuate the beam almost completely for both considered energies, causing negligible backscatter radiation. The spectrum at various depth and at the tissue‐plate interface has also been investigated.
From medical images to multiple‐biomarker microarrays
Authors: Wagner Robert F.
Published: December 2007

A favorite cliché, often attributed to Yogi Berra, is “Prediction is difficult, especially about the future!” In this brief review, we shall recall some historical difficulties in predicting the future of diagnostic medical imaging—in particular, the modern technologies of CT and MRI—and examine the analogous situation in the emerging technology of diagnostic microarrays for the multiple‐biomarker problem. All of these technologies began their lives as ill‐conditioned problems, i.e., there was insufficient data to solve the central problem at hand.
Ultrasonic measurements of breast viscoelasticity
Authors: Sridhar Mallika , Insana Michael F.
Published: December 2007

In vivo measurements of the viscoelastic properties of breast tissue are described. Ultrasonic echo frames were recorded from volunteers at while applying a uniaxial compressive force within a ramp time and holding the force constant for up to . A time series of strain images was formed from the echo data, spatially averaged viscous creep curves were computed, and viscoelastic strain parameters were estimated by fitting creep curves to a second‐order Voigt model. The useful strain bandwidth from this quasi‐static ramp stimulus was . The stress‐strain curves for normal glandular tissues are linear when the surface force applied is between 2 and . In this range, the creep response was characteristic of biphasic viscoelastic polymers, settling to a constant strain (arrheodictic) after . The average model‐based retardance time constants for the viscoelastic response were and . Also, the viscoelastic strain amplitude was approximately equal to that of the elastic strain. Above of applied force, however, the response of glandular tissue became increasingly nonlinear and rheodictic, i.e., tissue creep never reached a plateau. Contrasting in vivo breast measurements with those in gelatin hydrogels, preliminary ideas regarding the mechanisms for viscoelastic contrast are emerging.
A technical solution to avoid partial scan artifacts in cardiac MDCT
Authors: Primak A. N. , Dong Y. , Dzyubak O. P. , Jorgensen S. M. , McCollough C. H. , Ritman E. L.
Published: December 2007

Quantitative evaluation of cardiac image data obtained using multidetector row computed tomography (CT) is compromised by partial scan reconstructions, which improve the temporal resolution but significantly increase image‐to‐image CT number variations for a fixed region of interest compared to full reconstruction images. The feasibility of a new approach to solve this problem is assessed. An anthropomorphic cardiac phantom and an anesthetized pig were scanned on a dual‐source CT scanner using both full and partial scan acquisition modes under different conditions. Additional scans were conducted with the electrocardiogram (ECG) signal being in synchrony with the gantry rotation. In the animal study, a simple x‐ray detector was used to generate a signal once per gantry rotation. This signal was then used to pace the pig's heart. Phantom studies demonstrated that partial scan artifacts are strongly dependent on the rotational symmetry of angular projections, which is determined by the object shape and composition and its position with respect to the isocenter. The degree of partial scan artifacts also depends on the location of the region of interest with respect to highly attenuating materials (bones, iodine, etc.) within the object. Single‐source partial scan images (165 ms temporal resolution) were significantly less affected by partial scan artifacts compared to dual‐source partial scan images (82 ms temporal resolution). When the ECG signal was in synchrony with the gantry rotation, the same cardiac phase always corresponded to the same positions of the x‐ray tube(s) and, hence, the same scattering and beam hardening geometry. As a result, the range of image‐to‐image CT number variations for partial scan reconstruction images acquired in synchronized mode was decreased to that achieved using full reconstruction image data. The success of the new approach, which synchronizes the ECG signal with the position of the x‐ray tube(s), was demonstrated both in the phantom and animal experiments.
Saturn's Small Inner Satellites: Clues to Their Origins
Authors: Porco C. C. , Thomas P. C. , Weiss J. W. , Richardson D. C.
Published: December 2007

Cassini images of Saturn's small inner satellites (radii of less than ∼100 kilometers) have yielded their sizes, shapes, and in some cases, topographies and mean densities. This information and numerical
N
-body simulations of accretionary growth have provided clues to their internal structures and origins. The innermost ring-region satellites have likely grown to the maximum sizes possible by accreting material around a dense core about one-third to one-half the present size of the moon. The other small satellites outside the ring region either may be close to monolithic collisional shards, modified to varying degrees by accretion, or may have grown by accretion without the aid of a core. We derived viscosity values of 87 and 20 square centimeters per second, respectively, for the ring material surrounding ring-embedded Pan and Daphnis. These moons almost certainly opened their respective gaps and then grew to their present size early on, when the local ring environment was thicker than it is today.
Fine Thermal Structure of a Coronal Active Region
Authors: Reale Fabio , Parenti Susanna , Reeves Kathy K. , Weber Mark , Bobra Monica G. , Barbera Marco , Kano Ryouhei , Narukage Noriyuki , Shimojo Masumi , Sakao Taro , Peres Giovanni , Golub Leon
Published: December 2007

The determination of the fine thermal structure of the solar corona is fundamental to constraining the coronal heating mechanisms. The Hinode X-ray Telescope collected images of the solar corona in different passbands, thus providing temperature diagnostics through energy ratios. By combining different filters to optimize the signal-to-noise ratio, we observed a coronal active region in five filters, revealing a highly thermally structured corona: very fine structures in the core of the region and on a larger scale further away. We observed continuous thermal distribution along the coronal loops, as well as entangled structures, and variations of thermal structuring along the line of sight.
β-Lactam Failure in Treatment of Two Group G
Streptococcus dysgalactiae
subsp.
equisimilis
Pharyngitis Patients
Authors: Savini Vincenzo , Catavitello Chiara , Talia Marzia , Manna Assunta , Pompetti Franca , Di Bonaventura Giovanni , Di Giuseppe Nicola , Febbo Fabio , Balbinot Andrea , Di Zacomo Silvia , Esattore Francesca , D'Antonio Domenico
Published: December 2007

We present two cases of exudative pharyngitis due to
Streptococcus dysgalactiae
subsp.
equisimilis
, Lancefield group G. While the participation of this organism as an agent of pharyngitis is well documented, we focus on failure of beta-lactam therapy, a phenomenon that is well described for pharyngitis due to
Streptococcus pyogenes
. Therefore, these case reports add to our knowledge of pharyngitis caused by non-
S. pyogenes
streptococci.
Kaposi's Sarcoma-Associated Herpesvirus Induces Sustained Levels of Vascular Endothelial Growth Factors A and C Early during In Vitro Infection of Human Microvascular Dermal Endothelial Cells: Biological Implications
Authors: Sivakumar Ramu , Sharma-Walia Neelam , Raghu Hari , Veettil Mohanan Valiya , Sadagopan Sathish , Bottero Virginie , Varga Laszlo , Levine Rita , Chandran Bala
Published: December 2007

Kaposi's sarcoma (KS), a vascular tumor associated with human immunodeficiency virus type 1 infection, is characterized by spindle-shaped endothelial cells, inflammatory cells, cytokines, growth and angiogenic factors, and angiogenesis. KS spindle cells are believed to be of the lymphatic endothelial cell (LEC) type. Kaposi's sarcoma-associated herpesvirus (KSHV, or human herpesvirus 8) is etiologically linked to KS, and in vitro KSHV infection of primary human dermal microvascular endothelial cells (HMVEC-d) is characterized by the induction of preexisting host signal cascades, sustained expression of latency-associated genes, transient expression of a limited number of lytic genes, sustained induction of NF-κB and several cytokines, and growth and angiogenic factors. KSHV induced robust vascular endothelial growth factor A (VEGF-A) and VEGF-C gene expression as early as 30 min postinfection (p.i.) in serum-starved HMVEC-d, which was sustained throughout the observation period of 72 h p.i. Significant amounts of VEGF-A and -C were also detected in the culture supernatant of infected cells. VEGF-A and -C were also induced by UV-inactivated KSHV and envelope glycoprotein gpK8.1A, thus suggesting a role for virus entry stages in the early induction of VEGF and requirement of KSHV viral gene expression for sustained induction. Exogenous addition of VEGF-A and -C increased KSHV DNA entry into target cells and moderately increased latent ORF73 and lytic ORF50 promoter activation and gene expression. KSHV infection also induced the expression of lymphatic markers Prox-1 and podoplanin as early as 8 h p.i., and a paracrine effect was seen in the neighboring uninfected cells. Similar observations were also made in the pure blood endothelial cell (BEC)-TIME cells, thus suggesting that commitment to the LEC phenotype is induced early during KSHV infection of blood endothelial cells. Treatment with VEGF-C alone also induced Prox-1 expression in the BEC-TIME cells. Collectively, these studies show that the in vitro microenvironments of KSHV-infected endothelial cells are enriched, with VEGF-A and -C molecules playing key roles in KSHV biology, such as increased infection and gene expression, as well as in angiogenesis and lymphangiogenesis, thus recapitulating the microenvironment of early KS lesions.
Latent Membrane Protein 2B Regulates Susceptibility to Induction of Lytic Epstein-Barr Virus Infection
Authors: Rechsteiner Markus P. , Berger Christoph , Zauner Ludwig , Sigrist Jürg A. , Weber Matthias , Longnecker Richard , Bernasconi Michele , Nadal David
Published: December 2007

The B-lymphotropic Epstein-Barr virus (EBV) encodes two isoforms of latent membrane protein 2 (LMP2), LMP2A and LMP2B, which are expressed during latency in B cells. The function of LMP2B is largely unknown, whereas LMP2A blocks B-cell receptor (BCR) signaling transduction and induction of lytic EBV infection, thereby promoting B-cell survival. Transfection experiments on LMP2B in EBV-negative B cells and the silencing of LMP2B in EBV-harboring Burkitt's lymphoma-derived Akata cells suggest that LMP2B interferes with the function of LMP2A, but the role of LMP2B in the presence of functional EBV has not been established. Here, LMP2B, LMP2A, or both were overexpressed in EBV-harboring Akata cells to study the function of LMP2B. The overexpression of LMP2B increased the magnitude of EBV switching from its latent to its lytic form upon BCR cross-linking, as indicated by a more-enhanced upregulation and expression of EBV lytic genes and significantly increased production of transforming EBV compared to Akata vector control cells or LMP2A-overexpressing cells. Moreover, LMP2B lowered the degree of BCR cross-linking required to induce lytic EBV infection. Finally, LMP2B colocalized with LMP2A as demonstrated by immunoprecipitation and immunofluorescence and restored calcium mobilization upon BCR cross-linking, a signaling process inhibited by LMP2A. Thus, our findings suggest that LMP2B negatively regulates the function of LMP2A in preventing the switch from latent to lytic EBV replication.
Replication of Beta- and Gammaretroviruses Is Restricted in I/LnJ Mice via the Same Genetic Mechanism
Authors: Case Laure K. , Petell Lydia , Yurkovetskiy Leonid , Purdy Alexandra , Savage Katherine J. , Golovkina Tatyana V.
Published: December 2007

Mice of the I/LnJ inbred strain are unique in their ability to mount a robust and sustained humoral immune response capable of neutralizing infection with a betaretrovirus, mouse mammary tumor virus (MMTV). Virus-neutralizing antibodies (Abs) coat MMTV virions secreted by infected cells, preventing virus spread and hence the formation of mammary tumors. To investigate whether I/LnJ mice resist infection with other retroviruses besides MMTV, the animals were infected with murine leukemia virus (MuLV), a gammaretrovirus. MuLV-infected I/LnJ mice produced virus-neutralizing Abs that block virus transmission and virally induced disease. Generation of virus-neutralizing Abs required gamma interferon but was independent of interleukin-12. This unique mechanism of retrovirus resistance is governed by a single recessive gene,virusinfectivitycontroller1(vic1), mapped to chromosome 17. In addition to controlling the antivirus humoral immune response,vic1is also required for an antiviral cytotoxic response. Both types of responses were maintained in mice of the susceptible genetic background but congenic for the I/LnJvic1locus. Although thevic1-mediated resistance to MuLV resembles the mechanism of retroviral recovery controlled by theresistance toFriendvirus3(rfv3) gene, therfv3gene has been mapped to chromosome 15 and confers resistance to MuLV but not to MMTV. Thus, we have identified a unique virus resistance mechanism that controls immunity against two distinct retroviruses.
An Integrative Bioinformatic Approach for Studying Escape Mutations in Human Immunodeficiency Virus Type 1gagin the Pumwani Sex Worker Cohort
Authors: Peters Harold O. , Mendoza Mark G. , Capina Rupert E. , Luo Ma , Mao Xiaojuan , Gubbins Michael , Nagelkerke Nico J. D. , MacArthur Ian , Sheardown Brent B. , Kimani Joshua , Wachihi Charles , Thavaneswaran Subo , Plummer Francis A.
Published: December 2007

Human immunodeficiency virus type 1 (HIV-1) is able to evade the host cytotoxic T-lymphocyte (CTL) response through a variety of escape avenues. Epitopes that are presented to CTLs are first processed in the presenting cell in several steps, including proteasomal cleavage, transport to the endoplasmic reticulum, binding by the HLA molecule, and finally presentation to the T-cell receptor. An understanding of the potential of the virus to escape CTL responses can aid in designing an effective vaccine. To investigate such a potential, we analyzed HIV-1gagfrom 468 HIV-1-positive Kenyan women by using several bioinformatic approaches that allowed the identification of positively selected amino acids in the HIV-1gagregion and study of the effects that these mutations could have on the various stages of antigen processing. Correlations between positively selected residues and mean CD4 counts also allowed study of the effect of mutation on HIV disease progression. A number of mutations that could create or destroy proteasomal cleavage sites or reduce binding affinity of the transport antigen processing protein, effectively hindering epitope presentation, were identified. Many mutations correlated with the presence of specific HLA alleles and with lower or higher CD4 counts. For instance, the mutation V190I in subtype A1-infected individuals is associated with HLA-B*5802 (P= 4.73 × 10−4), a rapid-progression allele according to other studies, and also to a decreased mean CD4 count (P= 0.019). Thus, V190I is a possible HLA escape mutant. This method classifies many positively selected mutations across the entiregagregion according to their potential for immune escape and their effect on disease progression.
Evolution of the Chaperone/Usher Assembly Pathway: Fimbrial Classification Goes Greek
Authors: Nuccio Sean-Paul , Bäumler Andreas J.
Published: December 2007

Many Proteobacteria use the chaperone/usher pathway to assemble proteinaceous filaments on the bacterial surface. These filaments can curl into fimbrial or nonfimbrial surface structures (e.g., a capsule or spore coat). This article reviews the phylogeny of operons belonging to the chaperone/usher assembly class to explore the utility of establishing a scheme for subdividing them into clades of phylogenetically related gene clusters. Based on usher amino acid sequence comparisons, our analysis shows that the chaperone/usher assembly class is subdivided into six major phylogenetic clades, which we have termed α-, β-, γ-, κ-, π-, and σ-fimbriae. Members of each clade share related operon structures and encode fimbrial subunits with similar protein domains. The proposed classification system offers a simple and convenient method for assigning newly discovered chaperone/usher systems to one of the six major phylogenetic groups.
THE INFLUENCES OF THE MATERIAL AND GEOMETRICAL PROPERTIES OF SLIDING PLATE ON ERG EFFECT OF GEL-STRUCTURED ERF
Authors: SAITO S. , KAKINUMA Y. , AOYAMA T. , TANAKA K. , ANZAI H.
Published: December 2007

Electro-rheological Fluid (ERF) is the functional fluid that can change its viscoelastic property by applying electric field. However, ERF shows the sedimentation of the ER particles in long time use, and it caused the unstable ER effect. The Gel-structured ERF (ERG) has been developed to solve this problem. When a metallic flat plate is placed on the ERG sheet, ERG shows the high shear force due to the occurrence of the contact between the gel and the plate in response to the applying electric field (ERG effect). ERG effect can be obtained not only for metallic materials but also non-metallic materials by applying the one-sided electrode, and the ER effect is supposed to be considerably influenced by the material and geometrical properties of flat plate on the ERG sheet. In this study, the influences of the material and geometrical properties of sliding plate are experimentally analyzed from the viewpoint of the relative permittivity, surface roughness and flatness, and the design instruction for the selection of materials and their geometrical issues are proposed.
THE PHYSICAL MECHANISM TO REDUCE VISCOSITY OF LIQUID SUSPENSIONS
Authors: TAO R.
Published: December 2007

Reducing the viscosity of liquid suspensions is vital in science and engineering. This paper explores the physical mechanism for the viscosity reduction method in liquid suspension by pulsed electric or magnetic field. The key is that the maximum volume fraction to be available for the suspended particles in the suspension increases with the particle size and the polydispersity in the particle size distribution. Positive experimental results with various liquid suspensions indicate that this method, developed from the basic mechanism of viscosity, is universal and powerful for all liquid suspensions with broad applications.
VISCOELASTIC PROPERTIES OF SILICONE-BASED MAGNETORHEOLOGICAL ELASTOMERS
Authors: BÖSE HOLGER
Published: December 2007

Magnetorheological (MR) elastomers are composite materials consisting of magnetic particles in elastomer matrices, whose mechanical properties can be influenced by applying a magnetic field. Main parameters which determine the behavior of these smart materials are the concentration of the magnetic particles and the mechanical stiffness of the elastomer matrix. The viscoelastic properties of silicone-based MR elastomers are outlined in terms of their storage and loss moduli. The mechanical behavior of the material is also influenced by a magnetic field during the curing of the elastomer matrix, which leads to materials with anisotropic microstructures. The storage modulus of soft elastomer matrix composites can be increased in the presence of a magnetic field by significantly more than one order of magnitude or several hundreds of kPa. The relative increase exceeds that of all previously reported data. A shape memory effect, i. e. the deformation of an MR elastomer in a magnetic field and its return to original shape on cessasion of the magnetic field, is described.
POLAR MOLECULE TYPE ELECTRORHEOLOGICAL FLUIDS
Authors: LU KUNQUAN , SHEN RONG , WANG XUEZHAO , SUN GANG , WEN WEIJIA , LIU JIXING
Published: December 2007

The static and dynamic shear stress of newly developed electrorheological (ER) fluids can reach more than 100 kPa and over 60 kPa at 3 kV/mm, respectively. The high yield stress of those ER fluids and its near linear dependence on the electric field are different from the conventional ER fluids and can not be explained with traditional dielectric theory. Experiment demonstrates that the polar molecules adsorbed on the particles play crucial role in those ER fluids, which can be named as polar molecule type electrorheological (PM-ER) fluids. To explain PM-ER effect a model is proposed based on the interaction of polar molecule-charge in between the particles, where the local electric field is much higher than the external one and can cause the polar molecules aligning. The main effective factors for achieving high-performance PM-ER fluids are discussed.
NONLINEAR ALTERNATING CURRENT RESPONSES IN ELECTRORHEOLOGICAL FLUIDS: DYNAMIC EFFECTS
Authors: YU K. W. , TIAN W. J. , HUANG J. P.
Published: December 2007

By using a perturbation approach, we investigate dynamic effects on nonlinear alternating current (ac) responses in electrorheological (ER) fluids under an ac or a direct current electric field. We show that the dynamic effect due to a shear flow plays a significant role in the responses. Our results can be well interpreted in the dielectric dispersion spectral representation, and they offer a convenient method to determine the relaxation time and rotation velocity of ER particles by measuring the nonlinear ac responses.
INVESTIGATING THE TIME DEPENDENCE OF THE MR EFFECT
Authors: GONCALVES FERNANDO D. , CARLSON J. DAVID
Published: December 2007

Magnetorheological fluids are known to respond in a matter of milliseconds to the application of a magnetic field. To date, however, very little work has been done to study the time dependence of the MR response. The purpose of this study is to investigate the response time of the fluid. Experiments were conducted on a high shear rate rheometer capable of fluid speeds in excess of 35 m/s. With an MR valve length of 6.35 mm, the resulting dwell times were as low as 0.18 ms. For each of three magnetic field strengths, a reduction in yield stress is observed as dwell time decreases. A model is proposed to represent the time response of the fluid to the application of the magnetic field. The experimental data and the proposed model are used to identify the response time of the fluid for each field strength. Results indicate that as the magnetic field increases, the response time of the MR fluid decreases. For the range of magnetic field strengths considered in this study the response time of the fluid ranged from 0.24 ms to 0.19 ms.