bluuebunny/crossref_metadata_2025 huggingface dataset:
Dislocation junctions as barriers to threading dislocation migration
Authors: Quek Siu Sin , Wu Zhaoxuan , Zhang Yong-Wei , Xiang Yang , Srolovitz David J.
Published: January 2007

Level set simulations of dislocation dynamics in biaxially strained, heteroepitaxial films reveal interesting kinetic and thermodynamic mechanisms for blocking the migration of threading dislocations. Two dislocations on the same or on intersecting slip planes may react to form a threading dislocation segment that does not glide under the influence of the misfit strain. In the coplanar case, a kinetic barrier exists that slows down dislocation migration. For the reaction involving dislocations on intersecting planes, an energetic barrier impedes other advancing dislocations. These barriers create significant and frequent impediment to threading dislocation flow, resulting in pileups and high threading dislocation densities.
Searching with iterated maps
Authors: Elser V. , Rankenburg I. , Thibault P.
Published: January 2007

In many problems that require extensive searching, the solution can be described as satisfying two competing constraints, where satisfying each independently does not pose a challenge. As an alternative to tree-based and stochastic searching, for these problems we propose using an iterated map built from the projections to the two constraint sets. Algorithms of this kind have been the method of choice in a large variety of signal-processing applications; we show here that the scope of these algorithms is surprisingly broad, with applications as diverse as protein folding and Sudoku.
Duration of Time on Shift Before Accidental Blood or Body Fluid Exposure for Housestaff, Nurses, and Technicians
Authors: Green-McKenzie Judith , Shofer Frances S.
Published: January 2007

Background.

Shift work has been found to be associated with an increased rate of errors and accidents among healthcare workers (HCWs), but the effect of shift work on accidental blood and body fluid exposure sustained by HCWs has not been well characterized.

Objectives.

To determine the duration of time on shift before accidental blood and body fluid exposure in housestaff, nurses, and technicians and the proportion of housestaff who sustain a blood and body fluid exposure after 12 hours on duty.

Methods.

This retrospective, descriptive study was conducted during a 24-month period at a large urban teaching hospital. Participants were HCWs who sustained an accidental blood and body fluid exposure.

Results.

Housestaff were on duty significantly longer than both nursing staff (P = .02) and technicians (P < .0001) before accidental blood and body fluid exposure. Half of the blood and body fluid exposures sustained by housestaff occurred after being on duty 8 hours or more, and 24% were sustained after being on duty 12 hours or more. Of all HCWs, 3% reported an accidental blood and body fluid exposure, with specific rates of 7.9% among nurses, 9.4% among housestaff, and 3% among phlebotomists.

Conclusions.

Housestaff were significantly more likely to have longer duration of time on shift before blood and body fluid exposure than were the other groups. Almost one-quarter of accidental blood and body fluid exposures to housestaff were incurred after they had been on duty for 12 hours or more. Housestaff sustained a higher rate of accidental blood and body fluid exposures than did nursing staff and technicians.
Inclusive fitness and reproductive strategies in dwarf mongooses
Authors: Creel Scott R. , Waser Peter M.
Published: January 2007

Dwarf mongooses (Helogale parvula) are small, communally breeding carnivores found in woodland and tree-savanna throughout Africa. Within a pack, socially subordinate mongooses do not normally breed, yet they invariably participate in all aspects of parental care. The primary alternative to tolerating reproductive suppression is dispersal, which shortens the wait for dominance and breeding. Here, we calculate the annual inclusive fitness payoffs to the dispersing and nondispersing strategies for males and females of ages one to seven, using data from a 14-year study in Serengeti National Park, Tanzania. Factors with effects on inclusive fitness included relatedness to pack mates before and after dispersal, the effect of help on recipients' reproductive success, the probability of dispersing successfully, the probability of attaining dominance, and reproductive success after attaining dominance. All of these factors differed between male and female dwarf mongooses. We compared the contributions of direct and indirect fitness to the total fitness of mongooses pursuing each of the strategies, across a range of ages. In our population, dispersal and nondispersal both yielded direct and indirect payoffs at most ages. For dispersers of both sexes, direct fitness was the primary component of total fitness but indirect fitness was substantial for young (< 2 years old) dispersers. For nondispersers of both sexes, indirect fitness was the major component of total fitness among young mongooses (up to 2 or 3 years), but direct fitness was the major component among older mongooses. By comparing the inclusive fitness payoffs for the two strategies, we determined the range of ages at which dispersal should be favored for each sex. These comparisons correctly predicted that males should be more dispersive than females at all ages, and that males should disperse over a broader range of ages.
Visual Screening of Oral Cavity Cancer: The Role of Otolaryngologists
Authors: Yang Kung‐Yaun , Jiang Rong‐San , Shiao Jiun‐Yih , Wang Chen‐Chi , Wang Ching‐Ping , Liang Kai‐Li , Twu Chih‐Wen , Liu Shih‐An
Published: January 2007

Objectives: Because most screening was done by dentists, the purpose of this prospective cohort study was to evaluate the effectiveness of oral visual screening by otolaryngologists. In addition, we wanted to determine which group of enrolled patients was at potential risk of contracting oral cancer.

Methods: All male patients age ≥18 years who visited our clinic received oral mucosal screening. Basic data, including personal habits, were also obtained. A multivariate logistic regression model was devised to determine relevant risk factors for developing oral cancer.

Results: A total of 5,825 patients were enrolled in this study. Positive findings were found in 226 patients (3.9%). One hundred seventy‐two patients received biopsy and 131 patients were proven to have oral cancer (sensitivity rate: 76.2%). The results showed that those who smoked, consumed alcohol, and chewed betel quid on a regular basis were most likely to contract oral cancer (odds ratio = 49.81, 95% confidence interval = 29.38–84.42).

Conclusions: The otolaryngologists involved in this study successfully performed the oral screening. The sensitivity and specificity rates were both satisfactory. We suggest that those who are habitual cigarette smokers, alcohol consumers, and betel quid chewers should receive oral mucosal screening regularly so that potential oral cancer can be detected as early as possible.
Early Swallowing Problems in a Cohort of Patients With Nasopharyngeal Carcinoma: Symptomatology and Videofluoroscopic Findings
Authors: Ku Peter K. , Yuen Edmund H. , Cheung Dilys M. , Chan Becky Y. , Ahuja Anil , Leung S. F. , Tong Michael C. , van Hasselt Andrew
Published: January 2007

Objective: To study the incidence and the degree of swallowing dysfunction in patients with nasopharyngeal carcinoma (NPC) who underwent radiation therapy treatment.

Institution: The study was conducted in the Prince of Wales Hospital, a tertiary teaching hospital of the Chinese University of Hong Kong.

Materials and Methods: From October 1999 to July 2001, a cohort of 20 consecutive patients with newly diagnosed NPC was prospectively studied. Questions about symptoms, including swallowing functions, were asked, and head and neck examination including oromotor examination was performed in the subjects before radiation therapy. All patients were subjected to videofluoroscopy (VFSS) to assess their swallowing function. Abnormalities were scored if they were present on two of three swallow attempts. The patients were reassessed at 6 months and 12 months after radiotherapy by symptom assessment and VFSS.

Results: There were 14 male and 6 female patients. The mean age was 43.9 years. Nine patients had early (stage I and II) disease, whereas 11 patients had advanced (stage III and IV) disease. Nine patients were treated by radiation therapy only and 11 patients by concurrent chemoirradiation. Ninety‐five percent of the subjects had subjective dysphagia at 6 and 12 months after radiation therapy. Ninety percent had xerostomia, and 80% had to avoid certain foods at 12 months postradiation therapy. All subjects had to alternate solid food with fluid intake to facilitate swallowing. An average reduction of jaw movement by 1 cm was noted. A large proportion of patients had stasis of food in the pharynx (100% in valleculae and 60% in pyriform fossae) and impaired pharyngeal peristalsis (60%). One quarter of patients had laryngeal penetration.

Conclusions: Subjective swallowing difficulties were common in patients in the early follow‐up period after radiation therapy for NPC according to questionnaire assessment. An objective swallowing study revealed that swallowing dysfunction was persistent 12 months after radiation therapy.
Multiple Somatic Symptoms Linked to Positive Screen for Depression in Pediatric Patients With Chronic Abdominal Pain
Authors: Little Cheryl A , Williams Sara E , Puzanovova Martina , Rudzinski Erin R , Walker Lynn S
Published: January 2007

Objectives:

Abdominal pain is a frequent childhood complaint, comprising 2% to 4% of all reasons for pediatric office visits. Patients referred for evaluation of chronic abdominal pain (CAP) frequently present with comorbid nonspecific somatic symptoms that may complicate the medical evaluation and lead to unnecessary diagnostic tests and procedures. We tested the hypothesis that multiple nongastrointestinal (GI) symptoms in children presenting with CAP is a marker for clinically significant levels of depressive symptoms.

Methods:

Participants were 400 consecutive new patients (ages 8–17 years; 63% female) referred to the pediatric gastroenterology clinic for evaluation of abdominal pain of >3 months' duration. Patients reported how frequently they experienced 7 non‐GI symptoms. Patients were screened for depression with the Children's Depression Inventory.

Results:

On the basis of their Children's Depression Inventory scores, 58 (15%) patients had a positive screen for clinically significant depressive symptoms. Patients with a positive versus negative depression screen did not differ by sex, pain duration or laboratory evidence of organic disease. Patient report of ≥3 non‐GI symptoms maximized sensitivity (71%) and specificity (75%) in prediction of depression screening results. With each addition of a non‐GI symptom, the odds of a positive screen for depression doubled.

Conclusions:

For patients with and without organic disease findings associated with CAP, the presence of ≥3 non‐GI symptoms should signal the practitioner to evaluate for depression and may be used as an indicator of the likelihood of depression in the absence of specific inquiry into emotional symptoms.
Causes of Nutrition‐related Public Health Problems of Preschool Children: Available Diet
Authors: Allen Lindsay H
Published: January 2007

The primary goal of this review is to examine the timing and nature of dietary inadequacy during the first 5 years of life. An important issue is that many children in developing countries are already nutritionally depleted by the end of the first year of life, because maternal undernutrition can cause low fetal accumulation of nutrient stores and secretion of inadequate amounts of some micronutrients in breast milk. Improvement of maternal diet and micronutrient status is required to remedy this situation. During the period of complementary feeding, most households may be able to provide their young children with sufficient energy and protein from home‐produced complementary foods, but many do not feed foods with an adequate energy density or a sufficient number of meals per day. Inadequate micronutrient intakes and resulting deficiencies are common in preschoolers because of a lack of sufficient animal source foods, and have been associated with delayed child development. Dietary diversity is an especially important determinant of micronutrient intakes when animal source food intake is low. Interventions with animal source foods have produced improvements in growth, micronutrient status, cognitive performance and activity of children. Although much is now known about the role of inadequate diets in preschooler malnutrition, on a global scale the ability of households to apply this knowledge to improve the diets of their children is still limited.
Solutions to Nutrition‐related Health Problems of Preschool Children: Education and Nutritional Policies for Children
Authors: Darnton‐Hill Ian , Kennedy Eileen , Cogill Bruce , Hossain SM Moazzem
Published: January 2007

Objective:

By reviewing the literature, lessons learned and experience regarding the nutrition‐related health problems of preschool children, draw conclusions and make recommendations on education and nutrition policies for young children.

Results:

The most common causes of under‐5 mortality in low‐income countries have been identified as neonatal disorders, diarrhoea, respiratory infections, malaria, measles, and in some developing countries, AIDS. More than half (56%) of all child deaths have underlying malnutrition and undernutrition as a contributing factor. Children must have optimal growth and physical and intellectual development to learn and achieve their potential in society. Solutions include both preventive and curative interventions at all levels and include both improved health and education systems. Recent focus has been on health systems interventions that address averting deaths by cause for the 42 countries that account for 90% of worldwide under‐5 deaths (the majority in sub‐Saharan Africa). However, parallel or multisectoral interventions must be addressed to all children at risk for death, poor health and compromised growth and development. Adequate health care and nutrition is a human right, legally established in the Convention on the Rights of the Child.

Conclusions:

Improved health and nutrition will lead to enhanced economic development, but having a poverty focus appears to be essential, if poor people are not to be marginalized further. The HIV/AIDS pandemic illustrates this challenge clearly. The role of education, especially girls' education, in improved health and nutrition status of children and birth‐spacing is now clear, as is improving women's status. Increases in female status and education have been estimated to account for half of the reduction in child malnutrition rates during the past 25 years.
Aging affects motor learning but not savings at transfer of learning
Authors: Seidler Rachael D.
Published: January 2007

Two important components of skill learning are the learning process itself (motor acquisition) and the ability to transfer what has been learned to new task variants (motor transfer). Many studies have documented age-related declines in the ability to learn new manual motor skills. In this study, I tested whether the degree of savings at transfer of learning is similarly affected by advancing age. Young and older adults made aiming movements with a joystick to hit targets presented on a computer screen, with real-time feedback display of their movement. They adapted to three different rotations of the feedback display in a sequential fashion, with return to the normal feedback display between each. Adaptation performance was better when it was preceded by other adaptive experiences, regardless of age.
Excitability of the motor cortex during ovulatory and anovulatory cycles: a transcranial magnetic stimulation study
Authors: Hattemer Katja , Knake Susanne , Reis Janine , Rochon Justine , Oertel Wolfgang H. , Rosenow Felix , Hamer Hajo M.
Published: January 2007

Objective  The pathophysiology of catamenial diseases such as epilepsy is unclear. Therefore, we investigated changes in cortical excitability during anovulatory and ovulatory cycles.

Patients and methods  Using transcranial magnetic stimulation (TMS), eight healthy women were investigated during anovulatory and 12 during ovulatory cycles. On days 8, −14, −7 and 2 of the cycle, resting motor threshold (RMT), cortical silent period (CSP), intracortical inhibition (ICI) and intracortical facilitation (ICF) were investigated. Repeated‐measures analysis of variance (anova) and nonparametric methods were used for statistical analysis.

Results  A trend was seen for group by phase interaction regarding ICI (F = 2·5, P = 0·10). ICI varied during anovulatory cycles (median: 51·0% on day 8; 45·3% on day −14, 51·0% on day −7, and 28·6% on day 2; P = 0·040), mainly because of an increased inhibition on day 2. ICI was more pronounced in anovulatory cycles on day −14 (P = 0·021), −7 (P = 0·048) and 2 (P = 0·018) compared to ovulatory women who did not show intraindividual changes (P = 0·56). RMT, CSP and ICF showed no significant changes during anovulatory or ovulatory cycles.

Conclusions  The results suggest fluctuations in cortical excitability during anovulatory cycles, possibly due to the withdrawal of ‘excitatory’ oestrogens that initiate menses in anovulatory cycles.
Exogenous oestradiol and progesterone administration does not cause oedema in healthy young women
Authors: Stachenfeld Nina S. , Taylor Hugh S.
Published: January 2007

Objective  Oedema is an increase in the extravascular component of extracellular fluid volume (ECFV). Fluid movement across the ECF is controlled by hydrostatic and oncotic pressures, which are influenced by oestradiol and progesterone. Thus we hypothesized that oestradiol decreases, while combined oestradiol + progesterone increases, protein and fluid movement out of the vasculature.

Subjects  Subjects were eight healthy women (22 ± 2 years).

Design  Oestrogens and progesterone were suppressed with a gonadotropin‐releasing hormone antagonist for 16 days; oestradiol (2 × 0·1 mg/day patches) was added for days 5–16 (E2) and progesterone (200 mg/day) was added for days 13–16 (E2‐P4).

Measurements  We estimated intravascular (plasma) volume (PV), transcapillary albumin escape rate (TERalb), and Starling forces (hydrostatic pressures of plasma and interstitium, plasma colloid pressure, capillary filtration coefficient) in the forearm on days 2 (GnRH antagonist), 9 (E2) and 16 (E2‐P4).

Results  In E2, P[E2] increased from 85 ± 26 to 984 ± 136 pmol/ml (P < 0·05), with no change in P[P4]. In E2‐P4, P[E2] increased to 775 ± 195 pmol/ml and P[P4] increased from 6·4 ± 3·2 to 43·8 ± 16·2 nmol/l, P < 0·05). TERalb was lower during E2 (5·1 ± 0·9) and E2‐P4 (5·0 ± 1·1) compared to GnRH antagonist (5·8 ± 0·9%/h, P < 0·05). Plasma volume was unchanged by E2, and showed a trend (P = 0·07) for an increase during E2‐P4 (48·2 ± 2·9, 49·0 ± 3·0 and 53·9 ± 3·5 ml/kg for GnRH antagonist, E2, E2‐P4, respectively). Starling forces were unaffected by hormone treatments. Plasma renin activity and serum aldosterone concentration increased during E2‐P4.

Conclusions  Neither E2 nor E2‐P4 altered TERalb sufficiently to impact Starling forces indicating neither E2 nor P4 administration at these levels would likely cause oedema.
Vitrification of Boer Goat Morulae and Early Blastocysts by Straw and Open‐Pulled Straw Method
Authors: Hong Q‐H , Tian S‐J , Zhu S‐E , Feng J‐Z , Yan C‐L , Zhao X‐M , Liu G‐S , Zheng S‐M
Published: January 2007

Contents

The aim of this study was to investigate the effects of different vitrification solutions [EFS30 or EFS40 contains 30% (v/v) ethylene glycol (EG), 40% (v/v) EG; EDFS30 or EDFS40 contains 15% (v/v) EG and 15% (v/v) dimethyl sulfoxide (DMSO), 20% (v/v) EG and 20% (v/v) DMSO], equilibrium time during vitrification (0.5–2.5 min) and vitrification protocols [one‐step straw, two‐step straw and open‐pulled straw (OPS)] on in vivo development of vitrified Boer goat morulae and blastocysts after embryo transfer. In the one‐step straw method, the lambing rates of vitrified embryos in EFS30 (37.5%), EFS40 (40.5%) or EDFS30 (38.2%) group were similar to that of fresh embryos (57.5%) and conventional freezing method (46.7%) when the equilibrium time was 2 min. In the two‐step straw method, the highest lambing rate was obtained when embryos were pretreated with 10% EG for 5 min and then exposed to EFS40 for 2 min (51.4%), showing similar lambing rates compared with fresh embryos (56.1%) or the embryos cryopreserved by conventional freezing method (45.2%). In the OPS method, the lambing rate in EFS40, EDFS30 or EDFS40 groups were similar to that (57.1%) of fresh embryos, or to that (46.0%) of embryos cryopreserved by conventional freezing method. The highest lambing rate (51.4%) of the group of OPS was obtained when the embryos were vitrified with EDFS30. In conclusion, either the two‐step straw method in which embryos were pretreated in 10% EG for 5 min and then exposed to EFS40 for 2 min, or the OPS method in which embryos were pretreated in 10% EG + 10% DMSO for 30 s and then exposed to EDFS30 for 25 s was a simple and efficient method for the vitrification of Boer goat morulae and blastocysts.
Clove oil cream: a new effective treatment for chronic anal fissure
Authors: Elwakeel H. A. , Moneim H. A. , Farid M. , Gohar A. A.
Published: January 2007

Objective  Anal fissure is a common painful condition affecting the anal canal and causes considerable morbidity and reduction in quality of life. Surgical treatment has been associated with a degree of incontinence in up to 30% of patients. This study discussed the results of clove oil 1% cream in healing of chronic anal fissure.

Method  A single‐blind randomized comparative trial was setup to compare traditional treatment with stool softeners and lignocaine cream 5% against clove oil 1% cream for 6 weeks.

Results  55 patients were included in this study, 30 patients in clove oil group and 25 patients in control group. Healing had occurred in 60% of patients in clove oil group and in 12% of patients in the control group after 3‐month follow up (P < 0.001). Patients in clove oil group showed significant reduction in resting anal pressure and almost all other anorectal manometric pressures compared with patients in control group.

Conclusion  Topical application of clove oil cream demonstrated a significant beneficial effect when applied to patients suffering from chronic anal fissure.
Efficacy and Safety of Tadalafil in Men with Erectile Dysfunction with a High Prevalence of Comorbid Conditions: Results from MOMENTUS: Multiple Observations in Men with Erectile Dysfunction in National Tadalafil Study in the US
Authors: Goldstein Irwin , Kim Edward , Steers William D. , Pryor Jon L. , Wilde Dixon W. , Natanegara Fanni , Wong David G. , Ahuja Sanjeev
Published: January 2007

Introduction

Limited efficacy and safety data exist from open-label clinical trials of phosphodiesterase 5 inhibitors in men with erectile dysfunction (ED) and multiple comorbid (MCM) conditions, historically a difficult group to treat.

Aim

A multicenter study (Multiple Observations in Men with Erectile Dysfunction in National Tadalafil Study in the US) assessed efficacy and safety of tadalafil in men with ED and MCM conditions.

Main Outcome Measures

The primary end point was change from baseline in the erectile function (EF) domain of the International Index of Erectile Function. Secondary end points included the Sexual Encounter Profile, Global Assessment Questions, and Sexual Self-Confidence and Spontaneity Domains of the Psychological and Interpersonal Relationship Scales.

Methods

This was an open-label, multicenter study in men with ED. Tadalafil 20 mg was administered as needed prior to sexual activity, up to once/day, for 12 weeks following a 4-week ED-treatment-free period. The MCM group was 155 of 1,911 men enrolled in this study. Men in the MCM group met eligibility criteria but could not be included in other predefined groups: (i) Caucasian; (ii) Black American; (iii) Hispanic (groups 1–3, ≤65 years, no diabetes or depression); (iv) depression, ≤65 years, no diabetes; (v) diabetes, ≤65 years, no depression; (vi) >65 years, no diabetes or depression; and (vii) ED subsequent to traumatic spinal cord injury.

Results

Mean baseline EF domain score in MCM (mean age 65 ± 9 years) was 12.2 ± 6.5; 52% of subjects had severe ED; 72% diabetes mellitus; 67% cardiovascular disease (including hypertension); 49% hyperlipidemia; 38% depression; 84% had two or more comorbidities. At end point, there was a significant (P <0.001) mean change of 7.6 from baseline in mean EF domain score. Among men with severe ED, 22% achieved an EF domain score ≥26. Most common adverse events were headache 5.2%; flushing 3.9% and nasal congestion 3.2%; 3% discontinued use because of an adverse event.

Conclusion

In this open-label clinical trial of older men with ED and MCMs, tadalafil 20 mg significantly increased all efficacy end points and was well-tolerated.
DETECTION OF LISTERIA MONOCYTOGENES IN POWDERED MILK BY VIDAS LMO 2 – COLLABORATIVE STUDY
Authors: ROLA JOLANTA G. , KORPYSA‐DZIRBA WERONIKA , WOJTOŃ BOLESŁAW
Published: January 2007

A multilaboratory study was conducted in March 2005 to evaluate VIDAS Listeria monocytogenes II (LMO 2) immunoassay method for the detection of L. monocytogenes in milk products and to assess the ability of the laboratories to detect L. monocytogenes according to this method. Fourteen laboratories, representing government and industry, participated in this trial including the organizer – National Veterinary Research Institute – State Research Institute, Department of Hygiene of Food of Animal Origin. Each laboratory tested eight samples – three samples in blind duplicates containing L. monocytogenes on three levels of contamination and two uninoculated control samples. The participants have analyzed the samples with a mini‐VIDAS device that uses enzyme‐linked fluorescent assay technique. Twelve laboratories have obtained correct results in each analyzed sample. One laboratory obtained 50% accordance in medium level contaminated samples and one laboratory obtained 50% accordance in uninoculated control sample. All participants obtained 100% accuracy in samples contaminated with low and high levels of L. monocytogenes.
In Situ Investigation of Nanoabrasive Wear of Silicon
Authors: Ingole S. , Schwartzman A. , Liang H.
Published: January 2007

Investigation of abrasive wear at the nanometer-length scale is presented on single crystalline (001) and amorphous silicon. Experiments were performed using nanoindentation and nanoscratch approaches. Surface characterization was carried out using an atomic force microscope. Results show that both materials behave quite differently from each other during indentation and scratch. Specifically, amorphous silicon is proven to be more unstable during scratching than single crystal silicon. The comparison of in situ and ex situ normal displacement was made. Evidence was found on the hysteretic and viscoplastic behavior of amorphous silicon in nanoscratch that is also seen in indentation. Furthermore, it is found that this material is unstable under stress within small scales. Indications of phase transformation, (reverse) densification, and transition of elastic-plastic deformation are seen. These observations, enabled on silicon using an in situ and nanometer length scale process, are fundamentally different from the understanding of conventional abrasive wear.
Role of Distributed Interbristle Friction Force on Brush Seal Hysteresis
Authors: Zhao H. , Stango R. J.
Published: January 2007

Brush seals comprised of closely packed fine-diameter wires are an important innovation in seal technology for turbo-machinery. During service, brush seal bristles are subjected to a complex system of forces that are associated with various working loads including—but not limited to—aerodynamic forces, bristle tip∕rotor contact force, and interbristle interactions. The latter interactions are associated with contact forces that are exerted onto a bristle by adjacent fibers, as both forces and displacements are transmitted throughout the fibrous network. Such interbristle contact forces can be represented as uniformly distributed loads along the lateral surface of the fiber, or as applied discrete loads at various locations along the bristle length. In this paper, the role that uniformly distributed interbristle friction force plays in brush seal hysteresis is examined and reported. The origin of this frictional load is attributed to conjugate interbristle shear forces that arise due to compaction and aggregate displacement of the bristle pack during service. This, in turn, gives rise to a uniformly distributed internal micromoment that resists bending deformation. Numerical studies are reported for a brush seal whose bristle tips are subjected to rotor induced loading that is associated with bristle∕rotor interference or eccentric rotation of the shaft. In order to extend the range of applicability of numerical solutions, results are reported in terms of nondimensional brush seal design parameters. Results indicated that interbristle friction force can give rise to a delayed filament displacement as well as an incomplete bending recovery of bristles. The latter phenomenon can inevitably result in hysteretic “gapping,” i.e., the formation of an annular or crescent space between the rotor and bristle tips, thereby increasing vulnerability of the seal to leakage.
Computational Fluid Dynamics Analysis of Turbulent Flow Within a Mechanical Seal Chamber
Authors: Luan Zhaogao , Khonsari M. M.
Published: January 2007

Turbulent flow inside the seal chamber of a pump operating at high Reynolds number is investigated. The K−ε turbulence model posed in cylindrical coordinates was applied for this purpose. Simulations are performed using the fractional approach method. The results of the computer code are verified by using the FLUENT and by comparing to published results for turbulent Taylor Couette flow. Numerical results of four cases including two rotational speeds with four flush rates are reported. Significant difference between the laminar and the turbulence flow in the seal chamber is predicted. The behavior of the turbulent flows with very high Reynolds number was also investigated. The physical and practical implications of the results are discussed.
Synchronized dynamic dose reconstruction
Authors: Litzenberg Dale W. , Hadley Scott W. , Tyagi Neelam , Balter James M. , Ten Haken Randall K. , Chetty Indrin J.
Published: January 2007

Variations in target volume position between and during treatment fractions can lead to measurable differences in the dose distribution delivered to each patient. Current methods to estimate the ongoing cumulative delivered dose distribution make idealized assumptions about individual patient motion based on average motions observed in a population of patients. In the delivery of intensity modulated radiation therapy (IMRT) with a multi‐leaf collimator (MLC), errors are introduced in both the implementation and delivery processes. In addition, target motion and MLC motion can lead to dosimetric errors from interplay effects. All of these effects may be of clinical importance. Here we present a method to compute delivered dose distributions for each treatment beam and fraction, which explicitly incorporates synchronized real‐time patient motion data and real‐time fluence and machine configuration data. This synchronized dynamic dose reconstruction method properly accounts for the two primary classes of errors that arise from delivering IMRT with an MLC: (a) Interplay errors between target volume motion and MLC motion, and (b) Implementation errors, such as dropped segments, dose over/under shoot, faulty leaf motors, tongue‐and‐groove effect, rounded leaf ends, and communications delays. These reconstructed dose fractions can then be combined to produce high‐quality determinations of the dose distribution actually received to date, from which individualized adaptive treatment strategies can be determined.
Retrospective Monte Carlo dose calculations with limited beam weight information
Authors: Lindsay Patricia E. , El Naqa Issam , Hope Andrew J. , Vicic Milos , Cui Jing , Bradley Jeffrey D. , Deasy Joseph O.
Published: January 2007

An important unresolved issue in outcomes analysis for lung complications is the effect of poor or completely lacking heterogeneity corrections in previously archived treatment plans. To estimate this effect, we developed a novel method based on Monte Carlo (MC) dose calculations which can be applied retrospectively to RTOGAAPM‐style archived treatment plans (ATP). We applied this method to 218 archived nonsmall cell lung cancer lung treatment plans that were originally calculated either without heterogeneity corrections or with primitive corrections. To retrospectively specify beam weights and wedges, beams were broken into Monte Carlo‐generated beamlets, simulated using the VMC++ code, and mathematical optimization was used to match the archived water‐based dose distributions. The derived beam weights (and any wedge effects) were then applied to Monte Carlo beamlets regenerated based on the patient computed tomography densities. Validation of the process was performed against five comparable lung treatment plans generated using a commercial convolutionsuperposition implementation. For the application here (normal lung, esophagus, and planning target volume dose distributions), the agreement was very good. Resulting MC and convolutionsuperposition values were similar when dose distributions without heterogeneity corrections or dose distributions with corrections were compared. When applied to the archived plans (218), the average absolute percent difference between water‐based MC and water‐based ATPs, for doses above 2.5% of the maximum dose was . The average absolute percent difference between heterogeneity‐corrected MC and water‐based ATPs increased to . The average absolute percent difference between the MC heterogeneity‐corrected and the ATP heterogeneity‐corrected dose distributions was (available in 132/218 archives). The entire dose‐volume‐histograms for lung, tumor, and esophagus from the different calculation methods, as well as specific dose metrics, were compared. The average difference in maximum lung dose between water‐based ATPs and heterogeneity‐corrected MC dose distributions was . Potential errors in relying on primitive heterogeneity corrections are most evident from a comparison of maximum lung doses, for which the average MC heterogeneity‐corrected values were less than the ATP heterogeneity‐corrected values. We have demonstrated that recalculation of archived dose distributions, without explicit information about beam weights or wedges, is feasible using beamlet‐based optimization methods. The method provides heterogeneity‐corrected dose data consistent with convolution‐superposition calculations and is one feasible approach for improving dosimetric data for outcomes analyses.
An iterative three‐dimensional electron density imaging algorithm using uncollimated Compton scattered x rays from a polyenergetic primary pencil beam
Authors: Van Uytven Eric , Pistorius Stephen , Gordon Richard
Published: January 2007

X‐ray film‐screen mammography is currently the gold standard for detecting breast cancer. However, one disadvantage is that it projects a three‐dimensional (3D) object onto a two‐dimensional (2D) image, reducing contrast between small lesions and layers of normal tissue. Another limitation is its reduced sensitivity in women with mammographically dense breasts. Computed tomography (CT) produces a 3D image yet has had a limited role in mammography due to its relatively high dose, low resolution, and low contrast. As a first step towards implementing quantitative 3D mammography, which may improve the ability to detect and specify breast tumors, we have developed an analytical technique that can use Compton scatter to obtain 3D information of an object from a single projection. Imaging material with a pencil beam of polychromatic x rays produces a characteristic scattered photon spectrum at each point on the detector plane. A comparable distribution may be calculated using a known incident x‐ray energy spectrum, beam shape, and an initial estimate of the object's 3D mass attenuation and electron density. Our iterative minimization algorithm changes the initially arbitrary electron density voxel matrix to reduce regular differences between the analytically predicted and experimentally measured spectra at each point on the detector plane. The simulated electron density converges to that of the object as the differences are minimized. The reconstruction algorithm has been validated using simulated data produced by the EGSnrc Monte Carlo code system. We applied the imaging algorithm to a cylindrically symmetric breast tissue phantom containing multiple inhomogeneities. A preliminary ROC analysis scores greater than 0.96, which indicate that under the described simplifying conditions, this approach shows promise in identifying and localizing inhomogeneities which simulate calcifications with an image voxel resolution of and at a dose comparable to mammography.
Computation of the glandular radiation dose in digital tomosynthesis of the breast
Authors: Sechopoulos Ioannis , Suryanarayanan Sankararaman , Vedantham Srinivasan , D'Orsi Carl , Karellas Andrew
Published: January 2007

Tomosynthesis of the breast is currently a topic of intense interest as a logical next step in the evolution of digital mammography. This study reports on the computation of glandular radiation dose in digital tomosynthesis of the breast. Previously, glandular dose estimations in tomosynthesis have been performed using data from studies of radiation dose in conventional planar mammography. This study evaluates, using Monte Carlo methods, the normalized glandular dose to the breast during a tomosynthesis study, and characterizes its dependence on breast size, tissue composition, and x‐ray spectrum. The conditions during digital tomosynthesis imaging of the breast were simulated using a computer program based on the Geant4 toolkit. With the use of simulated breasts of varying size, thickness and tissue composition, the to the breast tissue was computed for varying x‐ray spectra and tomosynthesis projection angle. Tomosynthesis projections centered about both the cranio‐caudal (CC) and medio‐lateral oblique (MLO) views were simulated. For each projection angle, the ratio of the glandular dose for that projection to the glandular dose for the zero degree projection was computed. This ratio was denoted the relative glandular dose (RGD) coefficient, and its variation under different imaging parameters was analyzed. Within mammographic energies, the RGD was found to have a weak dependence on glandular fraction and x‐ray spectrum for both views. A substantial dependence on breast size and thickness was found for the MLO view, and to a lesser extent for the CC view. Although RGD values deviate substantially from unity as a function of projection angle, the RGD averaged over all projections in a complete tomosynthesis study varies from 0.91 to 1.01. The RGD results were fit to mathematical functions and the resulting equations are provided.
Human Cytomegalovirus UL38 Protein Blocks Apoptosis
Authors: Terhune Scott , Torigoi Emi , Moorman Nathaniel , Silva Maria , Qian Zhikang , Shenk Thomas , Yu Dong
Published: January 2007

Apoptosis is an innate cellular defense response to viral infection. The slow-replicating human cytomegalovirus (HCMV) blocks premature death of host cells prior to completion of the infection cycle. In this study, we report that the HCMV UL38 gene encodes a cell death inhibitory protein. A mutant virus lacking the pUL38 coding sequence, AD
dl
UL38, grew poorly in human fibroblasts, failed to accumulate viral DNA to wild-type levels, and induced excessive death of infected cells. Cells expressing pUL38 were resistant to cell death upon infection and effectively supported the growth of AD
dl
UL38. Cells infected with the pUL38-deficient virus showed morphological changes characteristic of apoptosis, including cell shrinkage, membrane blebbing, vesicle release, and chromatin condensation and fragmentation. The proteolytic cleavage of two key enzymes involved in apoptosis, namely, caspase 3 and poly(ADP-ribose) polymerase, was activated upon AD
dl
UL38 infection, and the cleavage was blocked in cells expressing pUL38. The pan-caspase inhibitor Z-VAD-FMK largely restored the growth of AD
dl
UL38 in normal fibroblasts, indicating that the defective growth of the mutant virus mainly resulted from premature death of host cells. Furthermore, cells expressing pUL38 were resistant to cell death induced by a mutant adenovirus lacking the antiapoptotic E1B-19K protein or by thapsigargin, which disrupts calcium homeostasis in the endoplasmic reticulum. Taken together, these results indicate that the HCMV protein pUL38 suppresses apoptosis, blocking premature death of host cells to facilitate efficient virus replication.
Evolution of CXCR4-Using Human Immunodeficiency Virus Type 1 SF162 Is Associated with Two Unique Envelope Mutations
Authors: Kiselyeva Yana , Nedellec Rebecca , Ramos Alejandra , Pastore Cristina , Margolis Leonid B. , Mosier Donald E.
Published: January 2007

CCR5-using human immunodeficiency virus type 1 (HIV-1) isolates typically gain CXCR4 use via multiple mutations in V3 and often V1/V2 regions of envelope, and patterns of mutations are distinct for each isolate. Here, we report that multiple CXCR4-using variants of a parental CCR5-using HIV-1 isolate, SF162, obtained by either target cell selection or CCR5 inhibition have a common mutation pattern characterized by the same two V3 mutations and that these mutations preexisted in some of the SF162 stocks. These results imply that SF162 has a single pathway for acquiring CXCR4 use and that prolonged culture is sufficient to select for R5X4 variants.
Timing, Trust and Transparency: Wage Restructuring at Glaxosmithkline
Authors: Pangarkar Nitin , Chung Yuen Kay
Published: January 2007

The economic ups and downs since the eruption of the Asian crisis in 1997 had prompted a wave of restructurings and job losses in Singapore and several other Asian countries. As a response, policy-makers in the Singapore government had urged companies to undertake wage reforms and to adopt more flexible wages. The wage restructuring exercise undertaken by the Singapore office of Glaxo Smithkline, one of the largest pharmaceutical companies in the world, in 2002 is studied in this case. Since the merger of Glaxo Welcome and SmithKline Beecham two years earlier, there had been consolidation with the less efficient plants in the system closing down. Although the Singapore plants were performing well, the impetus to restructure wages came primarily from a more competitive internal and external environment. Management believed that the introduction of Performance Bonus (PB) would lead to improved metrics and was essential for the company to compete in the changed environment. While the Union leadership was in broad agreement that the plant needed to remain competitive, it had some initial misgivings about the proposals put forth by management. This case charts the process of the wage restructuring exercise, illustrating some of the challenges that companies may face in implementing wage restructuring initiatives. We also examine the impact of different factors, as well as the process of implementation, on the success of such initiatives.
Sainand Beedis
Authors: Velayudhan Sanal Kumar
Published: January 2007

Sainand beedis was a small business that produced and sold beedis, which was a leaf wrapped tobacco product used for smoking. Sainand Beedis served parts of a district in the southern state of Andhra Pradesh in India. The competition for the firm was from strong regional brands. The firm offered lower priced beedis compared to the large regional brands. The quality of Sainand Beedis was similar to the quality of the competing regional brands. The firm provided superior service to channel members and also gave a higher trade commission. The result was a dominant position in the market it served. Its effort at geographical expansion to neighboring areas was affected by the difficulty in recruiting wholesalers. The competitor's distributor exerted its influence on the wholesalers in these new markets to prevent them from stocking Sainand Beedis. The inability to recruit wholesalers and the inability to service retailers directly hampered its growth plan. The large geographical spread of the semi-urban and rural markets intensified the distribution problem. The loyalty of the small town and rural consumer to existing brands was another important issue that hindered its growth.
Comparisons of the Millimeter and Submillimeter Bands for Atmospheric Temperature and Water Vapor Soundings for Clear and Cloudy Skies
Authors: Prigent Catherine , Pardo Juan R. , Rossow William B.
Published: January 2007

Geostationary satellites provide revisiting times that are desirable for nowcasting and observations of severe weather. To overcome the problem of spatial resolution from a geostationary orbit, millimeter to submillimeter wave sounders have been suggested. This study compares the capabilities of various oxygen and water vapor millimeter and submillimeter bands for temperature and water vapor atmospheric profiling at nadir in cloudy situations. It shows the impact of different cloud types on the received signal for the different frequency bands. High frequencies are very sensitive to the cloud ice phase, with potential applications to cirrus characterization.
Magnetic characterization of superparamagnetic nanoparticles pulled through model membranes
Authors: Barnes Allison L , Wassel Ronald A , Mondalek Fadee , Chen Kejian , Dormer Kenneth J , Kopke Richard D
Published: January 2007

Background

To quantitatively compare in-vitro and in vivo membrane transport studies of targeted delivery, one needs characterization of the magnetically-induced mobility of superparamagnetic iron oxide nanoparticles (SPION). Flux densities, gradients, and nanoparticle properties were measured in order to quantify the magnetic force on the SPION in both an artificial cochlear round window membrane (RWM) model and the guinea pig RWM.

Methods

Three-dimensional maps were created for flux density and magnetic gradient produced by a 24-well casing of 4.1 kilo-Gauss neodymium-iron-boron (NdFeB) disc magnets. The casing was used to pull SPION through a three-layer cell culture RWM model. Similar maps were created for a 4 inch (10.16 cm) cube 48 MGOe NdFeB magnet used to pull polymeric-nanoparticles through the RWM of anesthetized guinea pigs. Other parameters needed to compute magnetic force were nanoparticle and polymer properties, including average radius, density, magnetic susceptibility, and volume fraction of magnetite.

Results

A minimum force of 5.04 × 10-16 N was determined to adequately pull nanoparticles through the in-vitro model. For the guinea pig RWM, the magnetic force on the polymeric nanoparticles was 9.69 × 10-20 N. Electron microscopy confirmed the movement of the particles through both RWM models.

Conclusion

As prospective carriers of therapeutic substances, polymers containing superparamagnetic iron oxide nanoparticles were succesfully pulled through the live RWM. The force required to achieve in vivo transport was significantly lower than that required to pull nanoparticles through the in-vitro RWM model. Indeed very little force was required to accomplish measurable delivery of polymeric-SPION composite nanoparticles across the RWM, suggesting that therapeutic delivery to the inner ear by SPION is feasible.