bluuebunny/crossref_metadata_2025 huggingface dataset:
Texaco mortality study: II. Patterns of mortality among white males by specific job groups
Authors: Divine Barbara J. , Barron Virginia
Published: April 2007

While an earlier report on the Texaco Mortality Study cohort showed no statistically significant elevations for any cause of death for the white males, it did not preclude any excess risk of mortality within subgroups of workers. In this study, an employee's complete job history was used to determine his work categories, and patterns of mortality were examined for the more common job categories. All of the job categories examined showed deficits for mortality overall, and the patterns seen were similar to those for the entire cohort. Significant elevations were seen in pancreas cancer mortality for office and managerial people and in leukemia mortality for pipefitters and boilermakers. Other elevations of particular interest based on five or more deaths were brain cancer for laboratory workers and benign neoplasms in pipefitters and boilermakers. These associations were examined by latency and years worked, and no consistently positive associations were seen. It was not possible to take into account calendar time of exposure in this type of analysis, nor could any specific chemicals or levels of exposure be associated with the job categories where the standardized mortality ratios were elevated.
Early detection and signs of hepatoangiosarcoma among vinyl chloride workers
Authors: Sugita Minoru , Masuda Yoshinori , Tsuchiya Kenzaburo
Published: April 2007

Health examinations of 108 workers exposed to vinyl chloride monomer (VCM) at a Japanese chemical plant were carried out in 1979. The polymerization of vinyl chloride was started at the plant in 1949. In this study, the highest concentration of VCM in autoclaves was determined to be 250 ppm in 1961. However, the workers at the plant had been exposed to higher concentrations of VCM several times before 1960. More recent VCM exposure was considered negligible. Examinations assessed data on age, height, weight, obesity index, sake consumption, VCM exposure concentration, latent period, cumulative exposure, ICG (indocyano green test), serum bilirubin, GOT (glutamic oxaloacetic transaminase), GPT (glutamic pyruvic transminase), A1‐P (alkaline phosphatase), GGT(γ‐glutamyl transpeptidase), ZTT (zinc turbidity test), LDH (lactate dehydrogenase), cholesterol, TTT (thymol turbidity test), A/G (albumin globulin ratio), and thrombocytes. Variation in VCM exposure did not affect (1) tests of pigment excretion from the liver, such as ICG; (2) thrombocytes; and (3) enzyme activity (such as GPT); nor bilirubin or flocculation reaction in serum.
Pleural plaques and respiratory function
Authors: Järvholm Bengt , Sandén ÅKe
Published: April 2007

This cross‐sectional study was comprised of 202 nonsmoking shipyard workers with varying exposures to asbestos. Their chest X‐rays were normal or contained no abnormality other than pleural plaques. They participated in a health examination of workers exposed to asbestos, which comprised a total of 3,904 persons. One hundred and fifteen of the 202 workers had no deviations from normal X‐rays, and 87 had pleural plaques but no other finding on their X‐rays. Three out of the 115 workers with normal X‐rays and 13 of the 87 with pleural plaques had FVCs below the reference limits (p < 0.005). The workers with plaques had an average of 6.9% lower FVC. Even after stratification for asbestos exposure, men with plaques were found to have lower FVCs than men without plaques. This difference was largest for those with heavy exposure to asbestos.
Is occupational noise exposure during pregnancy a risk factor of damage to the auditory system of the fetus?
Authors: Lalande Nicole M. , Hétu Raymond , Lambert Jean
Published: April 2007

In the Province of Quebec, the regulated daily noise exposure limit is 90 dBA‐8h. This limit value also applies to pregnant women. Experimental studies suggest however, that this standard is not sufficiently stringent to protect the auditory system of the fetus, particularly in cases of low‐frequency noise exposure. An exploratory study was undertaken to assess this possibility. A total of 131 children were examined. Their mothers had worked, while pregnant with that child, in noise conditions ranging from 65 to 95 dBA‐8h. Results show (1) a three‐fold increase in the risk of having a high‐frequency hearing loss in the children whose mothers were exposed to noise in the range between a LAeq,9m of 85 to 95 dB, and (2) a significant increase in the risk of hearing loss at a frequency of 4000 Hz when these exposures involved a strong component of low‐frequency noise.
The morbidity and mortality of vermiculite miners and millers exposed to tremolite‐actinolite: Part I. Exposure estimates
Authors: Amandus H. E. , Wheeler R. , Jankovic J. , Tucker J.
Published: April 2007

The vermiculite ore and concentrate of a mine and mill near Libby, Montana, was found to be contaminated with fibrous tremolite‐actinolite. Of 599 fibers (length greater than 5 μm and width greater than 0.45 μm) counted in eight airborne membrane filter samples, 96% had an aspect ratio greater than 10 and 16% had an aspect ratio greater than 50. Additionally, 73% of the fibers were longer than 10 μm, 36% were longer than 20 μm, and 10% were longer than 40 μm. Estimates of exposure before 1964 in the dry mill were 168 fibers/cc for working areas, 182 fibers/cc for sweepers, 88 fibers/cc for skipping, and 13 fibers/cc for the quality control laboratory. In 1964–1971, exposure estimates for these areas were 33, 36, 17, and 3 fibers/cc, respectively. Estimates of exposures in the mine before 1971 ranged from 9–23 fibers/cc for drillers and were less than 2 fibers/cc for nondrilling jobs. All 8‐hr TWA job exposure estimates decreased from 1972‐1976, and from 1977‐1982 were less than 1 fiber/cc.
Bronchocarcinogenic properties of welding and thermal spraying fumes containing chromium in the rat
Authors: Berg Nils O. , Berlin Maths , Bohgard Mats , Rudell Bertil , Schütz Andrejs , Warvinge Karin
Published: April 2007

The possible bronchocarcinogenic effects of fumes released during the shielded metal arc welding of stainless steel and the thermal spraying of chromium oxide (Cr2O3) have been studied on the rat. The fume particles were shown to contain tri‐ and hexavalent chromium in soluble and low soluble forms; they were collected and implanted as pellets in the bronchi of groups of 100 rats by the method of Laskin et al. A negative control group of 100 rats was included, as well as positive controls receiving pellets containing benz(a)pyrene. The experiment was continued for 34 months; no differences of biological significance were noted between the growth rates, survival times, and terminal organ weights of the test and negative control groups. At autopsy, the macroscopic and microscopic appearance of the organs in the three groups, including the local reaction to the implanted pellet, were similar. No precancerous changes were observed at the implantation sites; one rat, who received a pellet containing welding fumes, showed squamous cell carcinoma remote from the implantation site and not associated with the bronchus. It had the appearance of a metastasis. All three benz(a)pyrene control rats developed cancer at the implantation site. The occupational health implications of these findings are discussed.
Respiratory symptoms associated with the use of azodicarbonamide foaming agent in a plastics injection molding facility
Authors: Whitehead Lawrence W. , Robins Thomas G. , Fine Lawrence J. , Hansen Doan J.
Published: April 2007

Respiratory health variables were studied cross‐sectionally in 227 employees of a plastics molding facility where numerous complaints had been apparently associated with the use of azodicarbonamide foaming agent in injection molding. Pre‐ and postshift respiratory status measures and azodicarbonamide concentrations were also obtained for 17 employees. Cross‐sectional pulmonary function differences by injection molding status were not observed. Modest decrements in pulmonary function measures were observed between start and end of shift but with no dose‐effect relationship. A strong association was observed for injection molding workers for eye/nose/throat irritation, cough, and wheezing. Additionally, wheezing, chest tightness, and symptoms of chronic bronchitis were strongly associated with work in injection molding during periods in which azodicarbonamide was in use. These results suggest respiratory symptom causation by some combination of azodicarbonamide itself, reaction products of azodicarbonamide formed during injection molding, or other unidentified agents uniquely associated with the process of injection molding with azodicarbonamide foaming agent.
Silica‐induced alveolar cell tumors in rats
Authors: Johnson N. F. , Smith D. M. , Sebring R. , Holland L. M.
Published: April 2007

Min‐U‐Sil5, a form of alpha quartz, has been shown to induce peripheral lung tumors in rats exposed to the dust by inhalation. The animals were exposed to a nominal particle concentration of 12.4 mg/m3 for 8 hr/day, 4 days/week, for 2 years. The induced tumors were large and peripheral, and, when examined by electron microscopy, were found to be composed predominantly of alveolar type II cells. These cells were found in papillary, acinar, and solid forms of the tumors and were characterized by lamellar inclusion bodies. This is in contrast to the mouse, in which the papillary form was associated with Clara cells and the acinar form was linked with the type II cell. In this study, the Clara cell was a minor component of the tumor mass. No clear risk is established in man linking silica exposure to increased lung tumor rates.
A rapid and simple method of extracting asbestos bodies from lung tissue by cytocentrifugation
Authors: Ehrlich Albert , Suzuki Yasunosuke
Published: April 2007

During analyses of alkali digested lung tissue for asbestos bodies, we observed that the number of asbestos bodies in the discarded waste frequently exceeded the number in the filtered residue, the number reported in the standard diagnostic method. This observation led to the exploration of alternative techniques that would optimize the recovery of asbestos bodies. We describe a new, simple, and rapid method for extracting asbestos bodies from digested lung tissue using a cytocentrifuge, in which the waste extraction and filtration steps are eliminated. Samples of digested lung tissue are ready for light microscopy after 10 minutes of cytocentrifugation directly onto a glass slide. The standard method was compared with the cytocentrifuge technique using lung tissue from four asbestos‐exposed workers and four controls with no known history of exposure. The number of asbestos bodies extracted by the centrifuge method was, on average, seven times higher than the number found with the standard method. A detailed quantitative study was made of the case that had the most asbestos bodies (comparison of the number of asbestos bodies counted in both “residue” and “waste”, applying the filtration and cytocentrifuge methods). The number of asbestos bodies found in the discarded waste significantly exceeded the number in the “reportable” filtered residue.
Occupational exposure to lead and blood pressure: A study in 105 workers
Authors: de Kort W. L. A. M. , Verschoor M. A. , Wibowo A. A. E. , van Hemmen J. J.
Published: April 2007

A group of workers, occupationally exposed to lead and cadmium compounds (n = 53), was compared to a group of workers not exposed to these metals (n = 52). The average values of systolic, diastolic, and mean blood pressure were found to be higher in the exposed group (p < 0.05). In contrast with the correlation between CdU and blood pressure, the correlation between PbB and systolic and mean blood pressure remained statistically significant after controlling for age and pulse rate (r = 0.22, p < 0.05). The prevalence of potential hypertension (defined as systolic blood pressure ≥ 160 mm Hg and/or diastolic blood pressure ≥ 95 mm Hg and/or under treatment for hypertension) was higher in the exposed group, but the observed relative risk was not statistically significant: relative risk = 1.91 (95% confidence limits, 0.90‐4.05). Furthermore, a significant correlation between PbB and Hgb (r = ‐0.28, p=0.004) was observed. Differences in kidney function, as assessed in this study, were not detected.
Cancer incidence and mortality among workers exposed to acrylonitrile
Authors: Chen Jean L. , Walrath Judy , O'Berg Maureen T. , Burke Cheryl A. , Pell Sidney
Published: April 2007

A cohort of 1,083 male employees who had potential for exposure to acrylonitrile between 1944 and 1970 at a Du Pont textile fibers plant were followed through 1981 for mortality and through 1983 for cancer incidence. In total, the 21 cancer deaths were fewer than expected based on either Du Pont or U.S. rates. No significant excesses were seen by primary site. In all, 37 cancer cases occurred as compared with 36.5 expected based on company rates. Five lung cancer cases were observed and 6.9 expected. There were 5 prostate cancer cases as compared with 1.9 expected. Of these, 4 occurred among wage employees during the 1975‐1983 period, compared to 0.9 expected. This excess was statistically significant.
Cancer mortality of capacitor manufacturing workers
Authors: Bertazzi Pier Alberto , Riboldi Luciano , Pesatori Angela , Radice Laura , Zocchetti Carlo
Published: April 2007

Experimental studies have demonstrated that certain types of commercially produced polychlorinated biphenyls (PCBs) are carcinogenic. Data in humans are still controversial. This study was undertaken in order to determine possible long‐term effects, particularly cancer, in workers engaged in the manufacture of capacitors impregnated with PCBs in a plant operating since 1946. All workers employed for at least 1 week between 1946 and 1978 were admitted to the study (544 males and 1,556 females), and their mortality was examined for the period 1946‐1982. Data on environmental contamination, workers' PCBs intake, and health effects (chloracne) were available, which documented the general exposure conditions in the plant. Vital status was ascertained for over 99% of the subjects, and death certificates were obtained for all deceased persons. Expected deaths were calculated using two sets of mortality rates, national and local. Among male workers, cancer deaths (14 obs.) were significantly increased as were deaths owing to cancer of the gastrointestinal (GI) tract (6 obs.). Also, mortality from hematologic neoplasms (3 obs.) and lung cancer (3 obs.) was higher than expected; however, the excess was statistically not significant. Female workers exhibited an overall mortality that was significantly increased above expectations. Cancer deaths (12 obs.) and hematologic neoplasms (4 obs.) were significantly higher than expected when compared with the local population. Interpretation of the results is limited by the small number of deaths; however, the point of interest is the consistency of these results with previous experimental and epidemiologic studies, which indicated the GI tract and lymphatic and hemopoietic tissue as the most probable target sites of the PCBs carcinogenic activity.
A cross‐sectional survey of kidney function in refinery employees
Authors: Viau C. , Bernard A. , Lauwerys R. , Buchet J. P. , Quaeghebeur L. , Cornu M. E. , Phillips S. C. , Mutti A. , Lucertini S. , Franchini I.
Published: April 2007

We examined sensitive biochemical and immunological markers of kidney function and damage in 53 male oil refinery workers exposed to hydrocarbons and compared their results with those of a control group of 61 age‐matched nonexposed males. The mean duration of employment of exposed males was 11 years. The current levels of exposure to a variety of aliphatic and aromatic hydrocarbons, as determined by personal monitoring, were well below the current threshold limit values. No difference was found in the urinary tubular parameters β‐N‐acetyl‐D‐glucosaminidase, β2‐microglobulin (β2‐m) and retinol‐binding protein. Similar serum β2‐m levels indicated no impairment of the glomerular filtration rate in the exposed workers. The levels of circulating immune complexes were also identical in both groups. The mean albuminuria was slightly higher (p < .005) in the exposed group in a quantitative assay but was not dipstick‐detectable. The mean urinary excretion of a renal antigen was also higher (p < .05) in the exposed group and correlated with the excretion of albumin. Finally, slightly higher titers of anti‐laminin antibodies were found in five exposed employees, but this was not accompanied by an increased albuminuria. We conclude that chronic low‐level hydrocarbon exposure in these refinery workers does not lead to clinically significant renal abnormalities. Nevertheless, some findings are consistent with the possible role of hydrocarbon exposure in the induction of renal disturbances.
Malignant mesothelioma in non‐asbestos textile workers in florence
Authors: Paci E. , Dini S. , Buiatti E. , Costantini A. Seniori , Lenzi S. , Zappa M.
Published: April 2007

By means of a review of histological diagnosis in the Pathology Department of the University of Florence, suspected cases of malignant mesothelioma, diagnosed in the period 1979–1984, were identified. Study of histological specimens permitted the selection of 13 cases of malignant mesothelioma resident in the Province of Florence. To these cases, referents were matched for age, sex, and year of hospital admission, with residence weighted for the general population of the Province. Both cases and referents (or their next of kin) completed an occupational questionnaire detailing possible occupational exposures. Out of the 13 cases of mesothelioma, 6 were textile workers and 5 of these were “rag‐sorters”. There were only 5 textile workers among the 52 controls. No asbestos cloth production plants have been in operation in the area from which the cases and referents are derived. Possible sources of exposure to asbestos in the textile industry of this area are discussed.
A case‐referent study of lung tumors in non‐asbestos textile workers
Authors: Paci E. , Buiatti E. , Geddes M.
Published: April 2007

A case series in the Province of Florence showed an increased risk of mesothelioma in textile workers (nonasbestos) and a survey of working conditions confirmed potential exposure to asbestos. In order to investigate the risk in textile workers, including some specific job titles, a case‐referent study on lung tumors was carried out. The lung cancer cases included 441 males with histologically confirmed primary lung cancer during the period 1980–1983. Referents included 1,075 males selected from two hospitals and matched for age, sex, and smoking habits. Those who had “ever worked” in the textile industry showed an adjusted odds ratio of 1.52 (95% C.I. 1–2.25) compared with other “industrial workers.” This moderately increased risk is maintained in selected jobs in the textile industry. An analysis of the modifying effect of time factors showed an increased risk in the period of 15–35 years from the date of first employment in the industry. The results support the hypothesis that a probable risk of lung cancer in textile workers in the Prato area was related to asbestos exposure.
Early detection of the nephrotoxic effects of industrial chemicals: State of the art and future prospects
Authors: Lauwerys Robert R. , Bernard Alfred
Published: April 2007

This paper discusses several tests that may permit the early detection of renal changes induced by long‐term exposure to nephrotoxic industrial chemicals and may possibly serve as advance warning of pending renal damage.

Some tests mainly attempt to assess the integrity of the glomerulus: high molecular weight proteinuria, glomerular basement membrane (GBM) antigens in blood and in urine, circulating anti‐GBM antibodies, glomerular filtration rate after an acute oral load of proteins, and estimation of membrane negative charges (ie, glomerular polyanion). Others mainly attempt to identify functional and/or morphological changes at the tubular level: low molecular weight proteinuria, aminoaciduria, glucosuria, hyperphosphaturia, hypercalciuria, enzymuria, tubular antigen excretion, kallikrein, and prostaglandin excretion.

Some of these tests are already routinely used, although controversy may still persist with regard to their clinical significance. Recently, new tests have been developed that may open new perspectives for assessing the significance of the early renal changes induced by chemicals.
Respiratory health status of gilsonite workers
Authors: Keimig Deborah Gellerman , Castellan Robert M. , Kullman Greg J. , Kinsley Kathleen B.
Published: April 2007

Gilsonite, a solidified hydrocarbon used in the manufacture of automotive body seam sealers, is mined only in the Uinta Basin of Eastern Utah and Western Colorado. Health effects of gilsonite dust exposure have not previously been published and exposure to gilsonite dust is not regulated. To examine potential respiratory health effects associated with gilsonite dust exposures, this cross‐sectional study surveyed the 100 current male employees who had been exposed to gilsonite dust at 3 existing gilsonite companies. Total dust exposures up to 28 times the nuisance dust standard were found, and 5 of 99 (5%) workers had chest radiographs consistent with pneumoconiosis of low profusion. Increased prevalences of cough and phlegm were found in workers with high‐exposure jobs, but no evidence for dust‐related pulmonary function impairment was noted. To prevent pulmonary health effects, we recommend reducing dust exposures for those workers in jobs currently characterized by relatively high dust exposures.
Occupational factors and carpal tunnel syndrome
Authors: Silverstein Barbara A. , Fine Lawrence J. , Armstrong Thomas J.
Published: April 2007

Carpal tunnel syndrome (CTS) is the most commonly reported nerve entrapment syndrome. The prevalence of CTS among 652 active workers in jobs with specific hand force and repetitiveness characteristics was estimated. The prevalence of CTS ranged from 0.6% among workers in low force–low repetitive jobs to 5.6% among workers in high force–high repetitive jobs. When controlling for potential confounders, the odds ratio for the high force‐high repetitive jobs was more than 15 (p < .001) compared to the low force–low repetitive jobs. High repetitiveness appears to be a greater risk factor than high force (odds ratio of 5.5, p < .05 versus 2.9 and not statistically significant).
Understanding student information behavior in relation to electronic information services: Lessons from longitudinal monitoring and evaluation, Part 1
Authors: Rowley Jennifer , Urquhart Christine
Published: April 2007

This two‐part article establishes a model of the mediating factors that influence student information behavior concerning electronic or digital information sources that support their learning. The first part reviews the literature that underpinned the development of the research methodology for the Joint Information Systems Committee (JISC) User Behavior Monitoring and Evaluation Framework, as well as the literature that has subsequently helped to develop the model over the 5 years the Framework operated in the United Kingdom, in five cycles of research that were adjusted to meet the emerging needs of the JISC at the time. The literature review attempts to synthesize the two main perspectives in the research studies: (a) small‐scale studies of student information behavior; and (b) the studies that focus on the quantitative usage of particular electronic information services in universities, often including implications for training and support. As the review indicates, there are gaps in the evidence concerning the browsing and selection strategies of undergraduate students and the interaction of some of the mediating influences on information behavior. The Framework developed a multimethod, qualitative and quantitative methodology for the continued monitoring of user behavior. This article discusses the methods used and the project‐management challenges involved, and concludes that at the outset, intended impacts need to be specified carefully, and that funding needs to be committed at that point for a longitudinal study. A research project on information behavior, intended to inform current policymaking on infrastructure provision, is inherently difficult as behavior changes lag behind provision.
Prediction of lateral pelvic node involvement in low rectal cancer by conventional computed tomography
Authors: Yano H , Saito Y , Takeshita E , Miyake O , Ishizuka N
Published: April 2007

Background

The clinical significance of lateral pelvic lymphatic spread in rectal cancer remains unknown. The present study aimed to assess the accuracy of preoperative computed tomography (CT) for prediction of lateral node involvement in patients with low rectal cancer and to determine the prognostic significance of extended lateral node dissection.

Methods

A total of 109 patients with primary low rectal cancer were enrolled in this prospective cohort study. The preoperative CT findings were compared with the histopathological results and with follow-up data.

Results

CT diagnosed lateral lymph node status with high accuracy (sensitivity 95 per cent, specificity 94 per cent), in marked contrast to mesorectal node status. Of 68 patients who had R0 resection without lateral node dissection, only two developed pelvic wall recurrence during median follow-up of 4·1 years. Metastatic nodes in the lateral pelvic region were significantly larger than those in the mesorectum (P < 0·001).

Conclusion

CT accurately predicted lateral lymph node status in low rectal cancer, allowing preoperative identification of patients who might benefit from extended lateral node dissection.
Preoperative but not postoperative systemic inflammatory response correlates with survival in colorectal cancer
Authors: Crozier J E M , McKee R F , McArdle C S , Angerson W J , Anderson J H , Horgan P G , McMillan D C
Published: April 2007

Background

The aim of the present study was to evaluate the relationship between the preoperative and postoperative systemic inflammatory response and survival in patients undergoing potentially curative resection for colorectal cancer.

Methods

One hundred and eighty patients with colorectal cancer were studied. Circulating concentrations of C-reactive protein (CRP) were measured before surgery and in the immediate postoperative period.

Results

The peak in CRP concentration occurred on day 2 (P < 0·001). During the course of the study 59 patients died, 30 from cancer and 29 from intercurrent disease. Day 2 CRP concentrations were dichotomized. In univariable analysis, advanced tumour node metastasis stage (P = 0·002), a raised preoperative CRP level (P < 0·001) and the presence of hypoalbuminaemia (P = 0·043) were associated with poorer cancer-specific survival.

Conclusion

Preoperative but not postoperative CRP concentrations are associated with poor tumour-specific survival in patients undergoing potentially curative resection for colorectal cancer.
How 77Se NMR Chemical Shifts Originate from Pre‐α, α, β, and γ Effects: Interpretation Based on Molecular Orbital Theory
Authors: Nakanishi Waro , Hayashi Satoko , Hada Masahiko
Published: April 2007

Plain rules founded in a theoretical background are presented that can be used to determine the structure of selenium compounds on the basis of δ(Se) data and to predict δ(Se) data from a given structure with satisfactory accuracy. As a first step to establish such rules, the origin of δ(Se) is elucidated on the basis of MO theory. The Se2− ion was chosen as the standard for the analysis. The concept of the pre‐α effect is proposed, which is defined as the downfield shift due to protonation of a lone‐pair orbital of Se. The pre‐α effect of two protons in H2Se is explained by the generation of double σ(SeH) and σ*(SeH) through protonation of the spherical Se2− ion. The orbitals, together with np(Se), result in effective transitions for the pre‐α effect. The α effect is the downfield shift caused by the replacement of SeH by SeMe. The extension of HOMO−2 [4py(Se)], HOMO−1 [4px(Se)], and HOMO [4pz(Se)] over the whole Me2Se molecule is mainly responsible for the α effect. The β effect originates not from the occupied‐to‐unoccupied (ψi→ψa) transitions but from the occupied‐to‐occupied (ψi→ψj) transitions. Although ψi→ψj transitions contribute to upfield shifts in Me2Se, the magnitudes become smaller as the methyl protons are substituted by Me groups one after another. The γ effect of upfield shifts is also analyzed, although complex. The effect of p(Se)–π(CC) conjugation is analyzed in relation to the orientational effect. Contributions from each MO (ψi) and each ψi→ψa transition are evaluated separately, by using a utility program derived from the Gaussian 03 program suite (NMRANAL‐NH03G). The treatment enables us to visualize and understand the origin of 77Se NMR chemical shifts.
Chiral Supramolecular Assemblies of a Squaraine Dye in Solution and Thin Films: Concentration‐, Temperature‐, and Solvent‐Induced Chirality Inversion
Authors: Jyothish Kuthanapillil , Hariharan Mahesh , Ramaiah Danaboyina
Published: April 2007

We prepared novel cholesterol‐appended squaraine dye 1 and model squaraine dye 2 and investigated their aggregation behavior in solution and thin films using photophysical, chiroptical, and microscopic techniques. Investigations on the dependence of aggregation on solvent composition (good/poor, CHCl3/CH3CN) demonstrated that squaraine dye 1 forms two novel H‐type chiral supramolecular assemblies with opposite chirality at different good/poor solvent compositions. Model compound 2 formed J‐type achiral assemblies under similar conditions. The supramolecular assembly of 1 observed at lower fractions of the poor solvent could be assigned to the thermodynamically stable form, while a kinetically controlled assembly is formed at higher fractions of the poor solvent. This assignment is evidenced by temperature‐ and concentration‐dependent experiments. With increasing temperature, the chirality of the kinetically controlled aggregate was lost and, on cooling, the aggregate with the opposite chirality was formed. On further heating and cooling the aggregates thus formed resulted in no significant changes in chirality, that is they are thermodynamically stable. Similarly, at lower concentrations, the thermodynamically stable form exists, but at higher concentration aggregation was found to proceed with kinetic control. Based on these observations it can be assumed that formation of the kinetically controlled assembly might be largely dependent on the presence of the nonpolar cholesterol moiety as well as the amount of poor solvent present. However, under solvent‐free conditions, structurally different aggregates were observed when drop cast from solutions containing monomer, whereas a left‐handed CD signal corresponding to the thermodynamically controlled assemblies was observed from pre‐aggregated solutions.
Molecular modeling of chiral‐modified zeolite HY employed in enantioselective separation
Authors: Jirapongphan Siricharn S. , Warzywoda Juliusz , Budil David E. , Sacco Albert
Published: April 2007

Insight into enantioselective separation utilizing chiral‐modified zeolite HY could be useful in designing a chiral stationary phase for resolving pharmaceutical compounds. A model was employed to better understand the enantioseparation of valinol in zeolite HY that contains (+)‐(1R;2R)‐hydrobenzoin as a chiral modifier. This model incorporates the zeolite support and accounts for the flexible change. Results from grand canonical Monte Carlo and molecular dynamics simulations indicate that the associated diastereomeric complex consists of a single (+)‐(1R;2R)‐hydrobenzoin and a single valinol molecules located in the zeolite HY supercage. Supercage‐based docking simulation predicted an enantioselectivity of 2.6 compared with that of 1.4 measured experimentally. Also, the supercage‐based docking simulation demonstrated a single binding motif in the S complex, and two binding motifs in the R complex. The multiple binding modes in the R complex resulted in its lower stability. This is hypothesized to be the origin of the weaker binding between (−)‐(R)‐valinol and the chiral modifier, and explains why (+)‐(R)‐valinol is retained more in the chiral‐modified zeolite system studied. Chirality, 2007. © 2007 Wiley‐Liss, Inc.
Evidence‐based guidelines for following stage 1 seminoma
Authors: Martin Jarad M. , Panzarella Tony , Zwahlen Daniel R. , Chung Peter , Warde Padraig
Published: April 2007

BACKGROUND.

The authors developed evidence‐based guidelines for a follow‐up schedule after orchiectomy for stage 1 seminoma. Required investigations, frequency of assessment, overall duration of follow‐up, and management strategies were identified.

METHODS.

A systematic review of the literature was performed of prospective studies in stage 1 seminoma. Studies published after 1980 were considered eligible for inclusion. Data extracted included relapse‐free rates, number of patients at risk, and relapse locations. Five strategies were identified: Surveillance, Extended‐Field Radiotherapy, Para‐aortic Radiotherapy, and either 1 or 2 cycles of Carboplatin Chemotherapy. For each strategy, Kaplan‐Meier relapse‐free estimates were used to calculate weighted‐mean cumulative hazards of relapse over time. These were used to calculate semiannual weighted‐mean relapse hazards.

RESULTS.

Seventeen prospective studies with a total of 5561 patients were identified. Actuarial data on relapse was available in 5013 (90.1%) patients, and 92.9% of all relapses had location data reported. Annual hazard rates for relapse were determined.

CONCLUSIONS.

Evidence‐based recommendations for follow‐up frequency based on risk of relapse were formulated. The authors suggested 3 times per year when the risk is >5%, 2 times per year when the risk is 1% to 5%, and annually until the risk is <0.3%. Investigations should reflect location(s) at risk of relapse and include computed tomography of the abdomen and pelvis for surveillance and adjuvant carboplatin, whereas for para‐aortic radiotherapy, pelvic computed tomography alone is required. These recommendations offer the possibility of maximal patient convenience and optimal healthcare resource allocation without compromising disease control. Cancer 2007. © 2007 American Cancer Society.
Some familiar examples for which the large deviation principle does not hold
Authors: Baxter J. R. , Jain N. C. , Varadhan S. R. S.
Published: April 2007

For a class of Markov processes (in continuous or discrete time) we show that if the full large deviation holds for normalized occupation time measures Lt(w, ˙) with some rate function J, then the lower semicontinuous regularization of J must agree with the rate function I introduced by M. D. Donsker and S. R. S. Varadhan. As a consequence we show that for processes such as Brownian motion the full large deviation principle for Lt(w, ˙) cannot hold with any rate function.
Asymptotic behavior of high‐order differences of the partition function
Authors: Knessl Charles , Keller Joseph B.
Published: April 2007

The partition function p(n) is the number of partitions of an integer n into positive integers, and p(n, k) = Δkp(n) is its k‐th difference. We obtain a recursion equation for p(n, k) which we solve asymptotically for n and k both large by using the WKB method and the method of matched asymptotic expansions. The result shows that p(n, k) is positive for n greater than a critical value n0(k). while for n < n0(k), p(n, k) alternates in sign as n increases. This confirms the recent result of A. M. Odlyzko. It also yields a refinement of his approximation for n0(k). The improved approximation agrees well with exact numerical values.
Large deviation problem for some parabolic itǒ equations
Authors: Chow Pao‐Liu
Published: April 2007

The large deviation problem of Wentzell‐Freidlin type is considered for a class of semilinear parabolic equations perturbed by a small multiplicative noise. In a Hilbert space setting, it is proved that, under suitable conditions, the associated family of solution measures, depending on a small parameter, obeys the large deviation principle with respect to a certain rate function.
Translation representation for automorphic solutions of the wave equation in non‐euclidean spaces, IV
Authors: Lax Peter D. , Phillips Ralph S.
Published: April 2007

In Part I of this series of papers we have defined the incoming and outgoing translation representations for automorphic solutions of the hyperbolic wave equations; in Part II we have proved the completeness of these representations when the fundamental polyhedron F has a finite number of sides with a finite or infinite volume, but is not compact. In Part IV we present a proof of completeness which is simpler than our original proof contained in Section 7 of Part II for the case when F has cusps of less than maximal rank; and we supply a proof for the case, not covered in Section 7, when the parabolic subgroup associated with such cusps contains twists.
On uniqueness and continuation properties after blow‐up time of self‐similar solutions of nonlinear schrödinger equation with critical exponent and critical mass
Authors: Merle Frank
Published: April 2007

We consider the nonlinear Schrödinger equation with critical power

where u: (0, T) × ℝN → C and ø ϕ H1 ∪ {ø;|x|ø ϵ L2}. With this nonlinear term, the equation (1)‐(1′) has a conformal invariance. Thus one yields explicit “self‐similar” solutions which have the following property: they have minimum L2 norm among blow‐up solutions.

In this paper, we first focus on uniqueness properties of these self‐similar solutions in a certain class. We then look at the possible continuations of these solutions after the blow‐up time.
Homogenization of linear and nonlinear transport equations
Authors: Weinan E.
Published: April 2007

We study the homogenization of the linear and nonlinear transport equations with oscillatory velocity fields. Two types of homogenized equations are derived. For general n‐dimensional linear and nonlinear problems, we derive homogenized equations by introducing additional independent variables to represent the small scales. For the two‐dimensional linear transport equations, we derive effective equations for the averaged quantities. Such equations take the form of either a degenerate non‐local diffusion equation with memory or a higher order hyperbolic equation. To study the nonlinear transport equations we introduce the concept of two‐scale Young measure and extend DiPerna's method to prove that it reduces to a family of Dirac measures.
Justification of the two‐dimensional equations of a linearly elastic shallow shell
Authors: Ciarlet P. G. , Miara B.
Published: April 2007

We consider a problem in three‐dimensional linearized elasticity, posed over a shell with a specific geometry, subjected to general loadings, and clamped on a portion of its lateral surface. We show that, as the thickness of the shell goes to zero, the solution of the three‐dimensional problem converges to the solution of two‐dimensional shallow shell equations. This approach, which provides in particular a mathematical definition of “shallowness”, clearly delineates conditions under which a three‐dimensional problem may be deemed asymptotically equivalent to a two‐dimensional shallow shell problem.
Biorthogonal bases of compactly supported wavelets
Authors: Cohen A. , Daubechies Ingrid , Feauveau J.‐C.
Published: April 2007

Orthonormal bases of compactly supported wavelet bases correspond to subband coding schemes with exact reconstruction in which the analysis and synthesis filters coincide. We show here that under fairly general conditions, exact reconstruction schemes with synthesis filters different from the analysis filters give rise to two dual Riesz bases of compactly supported wavelets. We give necessary and sufficient conditions for biorthogonality of the corresponding scaling functions, and we present a sufficient conditions for the decay of their Fourier transforms. We study the regularity of these biorthogonal bases. We provide several families of examples, all symmetric (corresponding to “linear phase” filters). In particular we can construct symmetric biorthogonal wavelet bases with arbitraily high preassigned regularity; we also show how to construct symmetric biorthogonal wavelet bases “close” to a (nonsymmetric) orthonormal basis.
Diffusion of color in the simple exclusion process
Authors: Quastel Jeremy
Published: April 2007

We prove a diffusion scaling limit for the macroscopic densities of colored particles performing the simply excluded random walk, and relate this to the limiting behavior of a test particle in equilibrium.
Regularity of harmonic maps from the Minkowski space into rotationally symmetric manifolds
Authors: Shath J. , Tahvildar‐Zadeh A.
Published: April 2007

We prove global regularity for the solution to the Cauchy problem with regular data for an equivariant harmonic map from the 2 + 1‐dimensional Minkowski space into a two‐dimensional, rotationally symmetric, and geodesically convex Riemannian manifold.
Large time behavior and homogenization of solutions of two‐dimensional conservation laws
Authors: Engquist Bjorn , Weinan E
Published: April 2007

We study the large time behavior of solutions of scalar conservation laws in one and two space dimensions with periodic initial data. Under a very weak nonlinearity condition, we prove that the solutions converge to constants as time goes to infinity. Even in one space dimension our results improve the earlier ones since we only require the fluxes to be nonlinear in a neighborhood of the mean value of the initial data. We then use these results to study the homogenization problem for scalar conservation laws with oscillatory initial data.
Statistical mechanics of classical particles with logarithmic interactions
Authors: Kiessling Michael K.‐H.
Published: April 2007

The inhomogeneous mean‐field thermodynamic limit is constructed and evaluated for both the canonical thermodynamic functions and the states of systems of classical point particles with logarithmic interactions in two space dimensions. The results apply to various physical models of translation invariant plasmas, gravitating systems, as well as to planar fluid vortex motion. For attractive interactions a critical behavior occurs which can be classified as an extreme case of a second‐order phase transition. To include in particular attractive interactions a new inequality for configurational integrals is derived from the arithmetic‐geometric mean inequality. The method developed in this paper is easily seen to apply as well to systems with fairly general interactions in all space dimensions. In addition, it also provides us with a new proof of the Trudinger‐Moser inequality known from differential geometry – in its sharp form.
Solution of the inverse spectral problem for an impedance with integrable derivative part I
Authors: Coleman Carol Flynn , McLaughlin Joyce R.
Published: April 2007

The inverse eigenvalue problem for a Sturm‐Liouville equation in impedance form with Dirichlet boundary conditions on a unit interval is considered. The solution of this nonlinear problem requires the investigation of a combined mapping from the logarithmic derivative of the impedance, assumed to be square integrable, to two sequences of spectral data. The first is the sequence of Dirichlet eigenvalues, shown to be locally bounded with square roots differing from the sequence of integral multiples of π by a square summable sequence. The second sequence has as first term the mean of the logarithmic derivative of the impedance. Each term in the remainder of the sequence is the logarithm of the product of the impedance and the derivative of an eigenfunction evaluated at an endpoint. It is shown that this is a locally bounded square summable sequence. The combined map is real analytic. The asymptotics and analyticity results follow from a modified Prüfer substitution. © 1993 John Wiley & Sons, Inc.
Perturbation theorems for linear hyperbolic mixed problems and applications to the compressible euler equations
Authors: Da Veiga H. Beirão
Published: April 2007

The main result of this paper (which is completely new, apart from our previous and less general result proved in reference [9]) states that the nonlinear system of equations (1.11) (or, equivalently, (1.10)) that describes the motion of an inviscid, compressible (barotropic) fluid in a bounded domain Ω, gives rise to a strongly well‐posed problem (in the Hadamard classical sense) in spaces Hk(Ω), k ≧ 3; see Theorem 1.4 below. Roughly speaking, if (an, ϕn) → (a, ϕ) in Hk × Hk and if fn → f in ℒ︁2(0, T;Hk), then (vn, gn) → (v, g) in 𝒞 (0, T; Hk × Hk). The method followed here (see also [8]) also applies to the non‐barotropic case p = p(ρ, s) (see [10]) and to other nonlinear problems. These results are based upon an improvement of the structural‐stability theorem for linear hyperbolic equations. See Theorem 1.2 below. Added in proof: The reader is referred to [29], Part I, for a concise explanation of some fundamental points in the method followed here. © 1993 John Wiley & Sons, Inc.
Korteweg–de vries zero dispersion limit: Through first breaking for cubic‐like analytic initial data
Authors: Wright Otis C.
Published: April 2007

The characteristic solution of the initial value problem for the Riemann invariant form of the Korteweg‐de Vries modulation equations is obtained locally through first breaking in the case of initial data which is analytic near a cubic inflection point. Tsarev's (see [11]) system is used to define the solution implicitly in terms of the speeds of the generalized KdV modulation equations. These “higher flow” speeds satisfy the same derivative identities obtained by Levermore for the KdV flow (see [6]).

Moreover, by explicitly constructing the Lax‐Levermore (see [5]) minimizer the Tsarev solution is shown to be the unique solution of Whitham's equations corresponding to the KdV zero dispersion limit. Also the Tsarev system possesses at most one three‐sheeted solution in a uniform neighborhood of the inflection point. Finally the explicit minimizer provides phase information for the Venakides' small dispersion KdV waveform through first breaking; see [12]. © 1993 John Wiley & Sons, Inc.
Multi‐valued solutions and branch point singularities for nonlinear hyperbolic or elliptic systems
Authors: Caflisch Russel E. , Ercolani Nicholas , Hou Thomas Y. , Landis Yelena
Published: April 2007

Multi‐valued solutions are constructed for 2 × 2 first‐order systems using a generalization of the hodograph transformation. The solution is found as a complex analytic function on a complex Riemann surface for which the branch points move as part of the solution. The branch point singularities are envelopes for the characteristics and thus move at the characteristic speeds. We perform an analysis of stability of these singularities with respect to perturbations of the initial data. The generic singularity types are folds, cusps, and nondegenerate umbilic points with non‐zero 3‐jet. An isolated singularity is generically a square root branch point corresponding to a fold. Two types of collisions between singularities are generic: At a “tangential” collision between two singularities moving at the same characteristic speed, a cube root branch point is formed, corresponding to a cusp. A “non‐tangential” collision, between two square root branch points moving at different characteristic speeds, remains a square root branch point at the collision and corresponds to a nondegenerate umbilic point. These results are also valid for a diagonalizable n‐th order system for which there are exactly two speeds. © 1993 John Wiley & Sons, Inc.