bluuebunny/crossref_metadata_2025 huggingface dataset:
Beyond the diffusion limit: Water flow through the empty bacterial potassium channel
Authors: Saparov Sapar M. , Pohl Peter
Published: March 2004

Water molecules are constrained to move with K
+
ions through the narrow part of the
Streptomyces lividans
K
+
channel because of the single-file nature of transport. In the presence of an osmotic gradient, a water molecule requires <10 ps to cross the purified protein reconstituted into planar bilayers. Rinsing K
+
out of the channel, water may be 1,000 times faster than the fastest experimentally observed K
+
ion and 20 times faster than the one-dimensional bulk diffusion of water. Both the anomalously high water mobility and its inhibition observed at high K
+
concentrations are consistent with the view that liquid–vapor oscillations occur because of geometrical confinements of water in the selectivity filter. These oscillations, where the chain of molecules imbedded in the channel (the “liquid”) cooperatively exits the channel, leaving behind a near vacuum (the “vapor”), thus far have only been discovered in hydrophobic nanopores by molecular dynamics simulations [Hummer, G., Rasaiah, J. C. & Noworyta, J. P. (2001)
Nature
414, 188–190; and Beckstein, O. & Sansom, M. S. P. (2003)
Proc. Natl. Acad. Sci. USA
100, 7063–7068].
Overcoming an evolutionary conflict: Removal of a reproductive organ greatly increases locomotor performance
Authors: Ramos Margarita , Irschick Duncan J. , Christenson Terry E.
Published: March 2004

One potential consequence of sexual size dimorphism is conflict among characters. For example, a structure evolved for reproduction can impair performance during other activities (e.g., locomotion). Here we provide quantitative evidence for an animal overcoming an evolutionary conflict generated by differential scaling and sexual size dimorphism by obligatorily removing an undamaged reproductive organ, and thus dramatically enhancing its locomotor performance. The spider genus
Tidarren
(Araneae, Theridiidae) is interesting because, within several species presenting extreme sexual size dimorphism (males representing ≈1% of the total mass of the female), males voluntarily remove one of their two disproportionately large pedipalps (modified copulatory organs; a single one represents ≈10% of the body mass in an adult) before achieving sexual maturity. Whether the left or right pedipalp is removed appears to be random. Previous researchers have hypothesized that pedipalp removal might enhance locomotor performance, a prediction that has remained untested. We found that, for male
Tidarren sisyphoides
, maximum speed increased (44%) significantly and endurance increased (63%) significantly after pedipalp removal. Furthermore, spiders with one pedipalp moved ≈300% greater distances before exhaustion and had a higher survival after exertion than those with two pedipalps. Removal of the pedipalp may have evolved in male
Tidarren
because of enhanced abilities to search for females (higher endurance and survival after exertion) and to out-compete rival males on the female's web (higher maximum speed). Our data also highlight how the evolution of conflicts can result in the evolution of a novel behavior.
Response of complex networks to stimuli
Authors: Bar-Yam Yaneer , Epstein Irving R.
Published: March 2004

We consider the response of complex systems to stimuli and argue for the importance of both sensitivity, the possibility of large response to small stimuli, and robustness, the possibility of small response to large stimuli. Using a dynamic attractor network model for switching of patterns of behavior, we show that the scale-free topologies often found in nature enable more sensitive response to specific changes than do random networks. This property may be essential in networks where appropriate response to environmental change is critical and may, in such systems, be more important than features, such as connectivity, often used to characterize network topologies. Phenomenologically observed exponents for functional scale-free networks fall in a range corresponding to the onset of particularly high sensitivities, while still retaining robustness.
Genome-wide identification of DNaseI hypersensitive sites using active chromatin sequence libraries
Authors: Sabo Peter J. , Humbert Richard , Hawrylycz Michael , Wallace James C. , Dorschner Michael O. , McArthur Michael , Stamatoyannopoulos John A.
Published: March 2004

Comprehensive identification of sequences that regulate transcription is one of the major goals of genome biology. Focal alteration in chromatin structure
in vivo
, detectable through hypersensitivity to DNaseI and other nucleases, is the sine qua non of a diverse cast of transcriptional regulatory elements including enhancers, promoters, insulators, and locus control regions. We developed an approach for genome-scale identification of DNaseI hypersensitive sites (HSs) via isolation and cloning of
in vivo
DNaseI cleavage sites to create libraries of active chromatin sequences (ACSs). Here, we describe analysis of >61,000 ACSs derived from erythroid cells. We observed peaks in the density of ACSs at the transcriptional start sites of known genes at non-gene-associated CpG islands, and, to a lesser degree, at evolutionarily conserved noncoding sequences. Peaks in ACS density paralleled the distribution of DNaseI HSs. ACSs and DNaseI HSs were distributed between both expressed and nonexpressed genes, suggesting that a large proportion of genes reside within open chromatin domains. The results permit a quantitative approximation of the distribution of HSs and classical cis-regulatory sequences in the human genome.
Relaxin regulation of endometrial structure and function in the rhesus monkey
Authors: Goldsmith Laura T. , Weiss Gerson , Palejwala Smita , Plant Tony M. , Wojtczuk Andrea , Lambert W. Clark , Ammur Nael , Heller Debra , Skurnick Joan H. , Edwards Dean , Cole Donna M.
Published: March 2004

Despite the documented importance of the protein hormone relaxin in reproduction in various mammalian species, the role of relaxin in human reproduction is poorly understood, largely because of the lack of studies in women or in suitable non-human primate models. Here we describe the establishment of a non-human primate model of early human pregnancy and its use in defining the actions of relaxin. Results demonstrate that relaxin exerts dramatic uterine effects including pronounced increase in uterine weight and stimulation of endometrial angiogenesis and resident endometrial lymphocyte number. In addition, relaxin decreases endometrial levels of matrix metalloproteinases 1 and 3 and increases levels of their endogenous inhibitor, tissue inhibitor of metalloproteinase 1, resulting in maintenance of endometrial collagen content. Relaxin significantly inhibits endometrial levels of estrogen receptor α, but not β, and of progesterone receptor isoforms A and B. The findings that relaxin stimulates new blood vessel formation and increases cytokine-containing lymphocyte number while maintaining endometrial connective tissue integrity are consistent with a significant role of relaxin in the establishment and/or maintenance of early pregnancy.
Metabolite-initiated protein misfolding may trigger Alzheimer's disease
Authors: Zhang Qinghai , Powers Evan T. , Nieva Jorge , Huff Mary E. , Dendle Maria A. , Bieschke Jan , Glabe Charles G. , Eschenmoser Albert , Wentworth Paul , Lerner Richard A. , Kelly Jeffery W.
Published: March 2004

Anfinsen showed that a protein's fold is specified by its sequence. Although it is clear why mutant proteins form amyloid, it is harder to rationalize why a wild-type protein adopts a native conformation in most individuals, but it misfolds in a minority of others, in what should be a common extracellular environment. This discrepancy suggests that another event likely triggers misfolding in sporadic amyloid disease. One possibility is that an abnormal metabolite, generated only in some individuals, covalently modifies the protein or peptide and causes it to misfold, but evidence for this is sparse. Candidate metabolites are suggested by the recently appreciated links between Alzheimer's disease (AD) and atherosclerosis, known chronic inflammatory metabolites, and the newly discovered generation of ozone during inflammation. Here we report detection of cholesterol ozonolysis products in human brains. These products and a related, lipid-derived aldehyde covalently modify Aβ, dramatically accelerating its amyloidogenesis
in vitro
, providing a possible chemical link between hypercholesterolemia, inflammation, atherosclerosis, and sporadic AD.
Recognition of single-stranded RNA viruses by Toll-like receptor 7
Authors: Lund Jennifer M. , Alexopoulou Lena , Sato Ayuko , Karow Margaret , Adams Niels C. , Gale Nicholas W. , Iwasaki Akiko , Flavell Richard A.
Published: March 2004

Viral infection of mammalian host results in the activation of innate immune responses. Toll-like receptors (TLRs) have been shown to mediate the recognition of many types of pathogens, including viruses. The genomes of viruses possess unique characteristics that are not found in mammalian genomes, such as high CpG content and double-stranded RNA. These genomic nucleic acids serve as molecular signatures associated with viral infections. Here we show that TLR7 recognizes the single-stranded RNA viruses, vesicular stomatitis virus and influenza virus. The recognition of these viruses by plasmacytoid dendritic cells and B cells through TLR7 results in their activation of costimulatory molecules and production of cytokines. Moreover, this recognition required intact endocytic pathways. Mice deficient in either the TLR7 or the TLR adaptor protein MyD88 demonstrated reduced responses to
in vivo
infection with vesicular stomatitis virus. These results demonstrate microbial ligand recognition by TLR7 and provide insights into the pathways used by the innate immune cells in the recognition of viral pathogens.
Body plan evolution of ascomycetes, as inferred from an RNA polymerase II phylogeny
Authors: Liu Yajuan J. , Hall Benjamin D.
Published: March 2004

The mode of evolution of the biologically diverse forms of ascomycetes is not well understood, largely because the descent relationships remain unresolved. By using sequences of the nuclear gene
RPB2
, we have inferred with considerable resolution the phylogenetic relationships between major groups within the phylum Ascomycota. These relationships allow us to deduce a historical pattern of body plan evolution. Within Taphrinomycotina, the most basal group, two simple body plans exist: uncovered asci with unicellular growth, or rudimentary ascoma with hyphal growth. Ancestral ascomycetes were filamentous; hyphal growth was lost independently in the yeast forms of Taphrinomycotina and Saccharomycotina. Pezizomycotina, the sister group to Saccharomycotina, retained mycelial growth while elaborating two basic ontogenetic pathways for ascoma formation and centrum development. The RPB2 phylogeny shows with significant statistical support that taxa in Pezizomycotina with ascohymenial ontogeny (ascoma generally forms after nuclear pairing) are ancestral and paraphyletic, whereas ascolocular fungi with fissitunicate asci are a clade derived from them. Ascolocular lichens are polyphyletic, whereas ascohymenial lichens comprise a monophyletic group that includes the Lecanorales. Our data are not consistent with a derived origin of Eurotiomycetes including
Aspergillus
and
Trichophyton
from within a lichen-forming ancestral group. For these reasons, the results of this study are considerably at variance with the conclusion that major fungal lineages are derived from lichensymbiotic ancestors. Interpretation of our results in the context of early work suggests that ascoma ontogeny and centrum characters are not in conflict with the molecular data.
POLYCYCLIC AROMATIC HYDROCARBONS IN THE ATMOSPHERE: MONITORING, SOURCES, SINKS AND FATE. I: MONITORING AND SOURCES
Authors: Pozzoli Luca , Gilardoni Stefania , Perrone Maria Grazia , de Gennaro Gianluigi , de Rienzo Massimo , Vione Davide
Published: March 2004

This is the first of a series of two papers intended to review the state‐of‐the‐art knowledge on atmospheric PAHs, concerning their monitoring, sources and transformation processes in the atmosphere. The monitoring section briefly introduces this class of compounds, mainly focusing on the 16 PAHs indicated by the US‐EPA as priority pollutants. These compounds undergo partitioning between the gas phase and particulate, which has to be considered in the choice of the sampling methodology. Furthermore, sampling artifacts may arise from further phase transfers inside the sampling device. After sampling, extraction, clean up and detection/quantification procedures will follow. They are closely related since the choice of the extraction technique will heavily condition the clean‐up step, and both procedures will place demands on the performance of the detection technique (usually GC‐MS or HPLC). This is particularly true in the case of complex samples such as those arising from atmospheric sampling. The sources of atmospheric PAHs are then discussed with a particular focus on receptor models, which can allow the apportionment of PAH sources based on concentration data that can be routinely obtained by pollution control networks.
SELECTIVE TRANSITION METAL EXTRACTION BY REVERSE MICELLES
Authors: Caselli Maurizio , Mangone Annarosa , Pellegrino Teresa , Traini Angela
Published: March 2004

In this report we have studied the extraction of a series of heavy metals ions (Cu2+, Ni2+, Fe3+, Cr3+, CrO42‐) from water bulk solutions by means of reverse micelles. The parameters explored are the nature and concentration of the accompanying electrolyte, as well as the surfactant nature and its concentration. The extracted metals can be recovered and eventually concentrated in a new water solution carrying out a back extraction.The extracted amount of metal is strongly dependent on the charge of the metal to be extracted. Therefore the extracted water solution is enriched in higher charge metal. Anions of amphoteric metals, like the chromate ions, can be quantitatively separated from their positive cations, like Cr3+ by properly choosing the cationic or the anionic surfactants.The transfer of the metal is essentially controlled by electrostatic forces. A model based on the Poisson‐Boltzmann distribution allow us to get the potential profile inside the water pool by determining the concentrations of the surfactant counter ions. From the potential profile and mass balance it is possible calculate the extraction percentage.
PENICILLAMINE DISULFIDE (PNS) AND ALKALINE CATIONS
Authors: Apruzzese Fabrizio , Bottari Emilio , Festa Maria Rosa
Published: March 2004

D‐penicillamine disulfide (PNS) shows protolytic properties and is able to form complexes with cations, because it has two aminic groups and two carboxylic groups. The four protonation constants of its deprotonated species were determined by means of electromotive force (e.m.f.) measurements of a galvanic cell involving a glass electrode at 25°C and in a constant ionic medium constituted by N(CH3)4Cl 3.00 or 1.00 mol dm‐3. At 25°C and in 3.00 mol dm‐3 N(CH3)4Cl as ionic medium, equilibria taking place between PNS and lithium, sodium and potassium ions were investigated. Experimental data, again obtained from e.m.f. measurements, were explained by assuming the formation of species of the type MH2PNS ed M2H2PNS, where M indicates a cation. Stability constants for each proposed species were calculated. A comparison with cystine is discussed.
HEAVY METAL IN SEDIMENTS AND BIOACCUMULATION IN THE BIVALVE Corbula gibba IN A DRILLING DISCHARGE AREA
Authors: Mauri Marina , Spagnoli Federico , Marcaccio Marco
Published: March 2004

The longterm bioavailability of heavy metals in sediments of a Northern Adriatic Sea shelf area affected by drilling mud and cutting discharges was discussed. Levels of Mn, Cu, Cr, Zn and Pb in different geochemical phases of the sediment and in soft tissues of the bivalve Corbula gibba were recorded and the relationships between biological and geochemical metal investigated. Total metal content, acetic acid extractable‐, exchangeable‐, carbonate‐, easily reducible‐, moderately reducible‐, oxidable‐ and residual‐fractions were determined on sediment samples. Corbula gibba was collected from wet sediments at the same times and sites, and the soft‐tissue metal contents were determined. Correlations show that the fractions with greatest bioavailability are the exchangeable and carbonate for Cr and the exchangeable, carbonate, easily and moderately reducible fractions for Zn. Data also show a possible bioavailability of Pb only from the residual fraction, consisting of very resistant matter of more recent anthropogenic origin. Near the platform, total Mn content in sediments and in C. gibba tissues show a strong correlation suggesting that this organism is sensitive to variations of the Mn‐oxi‐hydroxides superficial film. No relationships were found between biological and sediment‐bound Cu, however the discharged muds did not cause Cu enrichment. The metal fraction determined by weak acetic acid extraction at no point seems related to metal levels in Corbula gibba.
VALIDATION OF AN HPLC METHOD FOR THE DETERMINATION OF FLEROXACIN AND ITS PHOTO‐DEGRADATION PRODUCTS IN PHARMACEUTICAL FORMS
Authors: Djurdjevic Predrag , Laban Aleksandra , Jelikic‐Stankov Milena
Published: March 2004

HPLC determination of fleroxacin in dosage forms was carried out using either reversed‐phase column YMC pack ODS‐AQ or Supelco LC Hisep shielded hydrophobic phase column, with UV detection at 280 nm. The mobile phase for ODS column consisted of 50:50:0.5 v/v/v and for Hisep column 15:85:0.5 v/v/v acetonitrile‐water‐triethylamine. The pH of the mobile phase was adjusted to 6.30 for ODS column and to 6.85 for Hisep column, with H3PO4. Linear response was obtained in the concentration range of fleroxacin between 0.01 and 1.30 μg/mL. Detection limit was 4.8 ng/mL. Recovery test in the determination of fleroxacin in “Quinodis” tablets (Hoffmann La Roche, nominal mass 400 or 200 mg) was 98‐101% for both columns. The effect of the composition and pH of the mobile phase on spectra, retention time and dissociation constants of fleroxacin was discussed. The proposed method could be also used for separation of the photo‐degradation products of fleroxacin. Ten degradation products were separated on the ODS‐AQ column, thus confirming the suitability of the proposed method for stability study of fleroxacin in pharmaceuticals.
Assessment of occupational safety and health programs in small businesses
Authors: Barbeau Elizabeth , Roelofs Cora , Youngstrom Richard , Sorensen Glorian , Stoddard Anne , LaMontagne Anthony D.
Published: March 2004

Background

Occupational safety and health (OSH) programs are a strategy for protecting workers' health, yet there are few peer‐reviewed reports on methods for assessing them, or on the prevalent characteristics of OSH programs, especially in small businesses.

Methods

We adapted an occupational safety and health administration (OSHA) survey instrument to assess: management commitment and employee participation, workplace analysis, hazard prevention and control, and education and training. This was supplemented by a series of open‐ended questions. We administered the survey in 25 small worksites.

Results

Scores for each element ranged widely, with distribution of most scores being positively skewed. Barriers to addressing OSH included lack of time and in‐house expertise, and production pressures. External agents, including corporate parents, liability insurers, and OSHA, played an important role in motivating OSH programs.

Conclusions

Small businesses were able to mount comprehensive programs, however, they may rely on outside resources for this task. Being small may not be a barrier to meeting the requirements of an OSHA program management rule. Am. J. Ind. Med. 45:371–379, 2004. © 2004 Wiley‐Liss, Inc.
Heat illness in the U.S. mining industry
Authors: Michael Donoghue A.
Published: March 2004

Background

Heat illness is relatively common in the underground metalliferous mines of South Africa and Australia. Little is known about heat illness in other forms of mining and there have been no studies of heat illness in the US mining industry.

Methods

Mine Safety and Health Administration (MSHA) accident, injury, illness, and employment data were used to study heat illness reported by the US mining industry from January 1, 1983 to December 31, 2001.

Results

Five hundred thirty eight cases of heat illness were reported. None of these cases were fatal. Four hundred twenty seven cases (79.4%) occurred in the summer months of June, July, and August. Incidence rates of heat illness in underground mining ranged from 0.00275/106 person‐hours for coal, to 0.168/106 person‐hours for metal, rate‐ratio = 61.1 (P < 0.001). Incidence rates in surface mining ranged from 0.0265/106 person‐hours for coal, to 0.0644/106 person‐hours for stone, rate‐ratio = 2.43 (P < 0.001). Incidence rates in mills/preparation plants ranged from 0.0255/106 person‐hours for coal, to 0.417/106 person‐hours for stone, rate‐ratio = 16.4 (P < 0.001).

Conclusions

Heat illness occurs most frequently in stone mills, metal mills, and underground metal mines. Preventive measures should target the summer months of June, July, and August. Am. J. Ind. Med. 45:351–356, 2004. © 2004 Wiley‐Liss, Inc.
More evidence of the need for an ergonomic standard
Authors: Biddle Jeff , Roberts Karen
Published: March 2004

Background

In 1999, the Occupational Safety and Health Administration (OSHA) proposed regulations designed to reduce work related inquiries by limiting worker exposure to “ergonomic risk factors.” Congress subsequently overturned the regulations. We provide additional evidence on earnings losses attributable to musculoskeletal disorders (MSDs), and thus on the need for an ergonomic standard.

Methods

Regression techniques are used to analyze data from a survey of injured workers that has been matched to employer‐reported earnings data covering pre‐ and post‐injury periods, and to workers' compensation claims records.

Results

MSDs lead to large and persistent earnings losses. Cost estimates used by OSHA to justify the 1999 EPS are corroborated. Losses are greatest among workers who file workers compensation claims, but nonclaimants also have losses.

Conclusions

Earnings losses and lost productivity associated with work‐related MSDs are substantial and an ergonomic standard could be cost effective. Am. J. Ind. Med. 45:329–337, 2004. © 2004 Wiley‐Liss, Inc.
Prevalence and reporting of occupational illness by company size: Population trends and regulatory implications
Authors: Morse Tim , Dillon Charles , Weber Joseph , Warren Nick , Bruneau Heather , Fu Rongwei
Published: March 2004

Background

Reports of occupational disease using the Bureau of Labor Statistics (BLS)/OSHA survey have shown increasing rates with larger establishment size. The literature is divided on whether this pattern is an artifact of under‐reporting in smaller businesses or is the result of differences in underlying risk factors.

Methods

A population‐based survey [the Connecticut Upper‐Extremity Surveillance Project (CUSP)] assessing prevalence of likely work related musculoskeletal disorders (MSD) in CT, coded by establishment size, is compared to CT MSD incidence rates based on the BLS/OSHA survey.

Results

When analyses were controlled for age, gender, physical risks, and occupation, there was a marginally significant association between business size and the rate of MSD [odds ratio (OR) = 0.91, CI 0.82–1.01], but in the opposite direction of the BLS/OSHA rates, with larger businesses having somewhat lower rates of MSD. Reported risk factors varied in a similar direction, though with mid‐sized companies having the highest physical risks.

Conclusions

The increased rates of occupational illness in larger businesses reported in the BLS/OSHA survey does not appear to be due to actual incidence or distribution of risk factors, but appears more likely to be due to under‐reporting in smaller businesses. Estimates based on the assumption that the ORs based on size are actually similar to the CUSP population survey results suggest that MSD incidence is approximately 3.6‐times the reported rates. Am. J. Ind. Med. 45:361–370, 2004. © 2004 Wiley‐Liss, Inc.
Co‐worker fatalities from hydrogen sulfide
Authors: Hendrickson Robert G. , Chang Arthur , Hamilton Richard J.
Published: March 2004

Background

Hydrogen sulfide is a colorless, odorless gas that may cause rapid loss of consciousness and respiratory depression without warning. It has produced toxicity in workers in numerous industries and occupations.

Methods

A review of the United States Bureau of Labor Statistics (USBLS) Census of Fatal Occupational Injuries (CFOI) for occupational deaths related to hydrogen sulfide from 1993 to 1999 was performed.

Results

Fifty‐two workers died of hydrogen sulfide toxicity in this 7‐year period. Deaths were most commonly reported in workers who were white (85%), male (98%), and in their first year of employment with the company (48%). Common industries included waste management, petroleum, and natural gas. In 21% of cases, a co‐worker died simultaneously or in the attempt to save the workers.

Conclusions

Hydrogen sulfide toxicity is uncommon, but potentially deadly. Toxicity is predominantly in new workers and co‐worker fatalities occur in a significant minority of cases. Proper training and education on the warning signs of hydrogen sulfide toxicity may help reduce worker fatalities. Am. J. Ind. Med. 45:346–350, 2004. © 2004 Wiley‐Liss, Inc.
Fatal rat bite fever in a pet shop employee
Authors: Shvartsblat Steve , Kochie Mary , Harber Philip , Howard John
Published: March 2004

Background

Rat bite fever is a zoonotic disease that has been described in laboratory personnel as well as the general population.

Methods

A 24‐year‐old male pet shop employee contracted the disease through a minor superficial finger wound on a contaminated rat cage. The disease progressed from a flu‐like illness to endocarditis involving first the aortic valve and then the mitral valve and septum. Despite aggressive therapy including two surgical procedures, the patient died from sepsis and multi‐organ system failure 59 days after initial injury.

Results

This is the first reported case of rat‐bite fever (RBF) in a pet shop work setting.

Conclusions

Zoonotic infections may present a significant hazard to workers handling animals. Education on hazards of animal contact and other preventive measures are needed in small places of business like pet shops. Am. J. Ind. Med. 45:357–360, 2004. © 2004 Wiley‐Liss, Inc.
Implications of the Precautionary Principle in research and policy‐making
Authors: Grandjean Philippe , Bailar John C. , Gee David , Needleman Herbert L. , Ozonoff David M. , Richter Elihu , Sofritti Morando , Soskolne Colin L.
Published: March 2004

The Precautionary Principle (PP) has recently been formally introduced into national and international law. The key element is the justification for acting in the face of uncertainty. The PP is thereby a tool for avoiding possible future harm associated with suspected, but not conclusive, environmental risks. Under the PP, the burden of proof is shifted from demonstrating the presence of risk to demonstrating the absence of risk and it is the responsibility of the producer of a technology to demonstrate its safety rather than the responsibility of public authorities to show harm. Past experiences show the costly consequences of disregarding early warnings about environmental hazards. Today, the need for applying the PP is even greater. New research is needed to expand current insight into disease causation, to elucidate the full scope of potential adverse implications resulting from environmental pollutants, and to identify opportunities for prevention. Research approaches should be developed and strengthened to counteract innate ideological biases and to support our confidence in applying the PP for decision‐making in the public policy arena. Am. J. Ind. Med. 45:382–385, 2004. © 2004 Wiley‐Liss, Inc.
Assessing the accuracy of OSHA's projections of the benefits of new safety standards
Authors: Seong Si Kyung , Mendeloff John
Published: March 2004

Background

In the preambles to the safety and health standards that it has issued since 1987, the Occupational Safety and Health Administration (OSHA) projected that new safety standards would prevent over 2,600 death each year. For six safety standards issued since 1990, we compare OSHA's projections of the impact of full compliance on fatalities with actual fatality changes and examine the reasons for the differences.

Methods

We reviewed the preambles to OSHA standards and the Regulatory Impact Analyses (RIAs) prepared for them to identify the baseline and the prevention factor that the agency used to project the number of deaths that would be prevented. We used three data sources to track the relevant categories of fatalities: the Census of Fatal Occupational Injuries (CFOI), the National Traumatic Occupational Fatality program, and OSHAs Fatality/Catastrophe investigations.

Results

For all six standards, OSHA appeared to overestimate the number of deaths prevented. The availability of CFOI led to better estimates of the fatality baseline, but the prevention factor was always overestimated, especially for standards which emphasized training.

Conclusions

OSHA needs to develop better methods for projecting injury impacts. Research is needed to help OSHA predict the effects of behavioral requirements (e.g., training) on actual work practices and injury outcomes. For non‐fatal injuries, new methods of data collection will be required. Am. J. Ind. Med. 45:313–328, 2004. © 2004 Wiley‐Liss, Inc.
A Survey of Some Global Methods for Solving Two‐Point BVPs
Authors: Cash J. R.
Published: March 2004

The task of comparing numerical methods which are designed to solve a particular class of problems is a notoriously difficult and inexact one. However it is important to be able to measure the quality of codes in at least a limited sense so that potential users of the software can have some guidance as to which code they might use to solve their particular problem. There are two important aspects that must be considered when numerical comparisons are contemplated. The first is to classify those codes which can be regarded as being reasonably efficient and so can set a standard against which other codes can be compared. The second is to identify some test problems which will challenge the codes and highlight any weaknesses they may have. In the present paper we consider the first of these two problems and we describe some codes which may be regarded as being amongst the most efficient for solving two‐point boundary value problems at the present time. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sensitivity analysis and fast computation of packet loss probabilities in multiplexer models
Authors: Cuyt A. , Lenin R. B. , Van der Borght K.
Published: March 2004

A statistical multiplexer is a basic model used in the design and the dimensioning of communication networks. The multiplexer model consists of a finite buffer, to store incoming packets, served by a single server with constant service time, and a more or less complicated arrival process. The aim is to determine the packet loss probability as a function of the capacity of the buffer. An exact analytic approach is unfeasible in real time, and hence we show how techniques from rational approximation theory can be applied to the computation of the packet loss. Since the parameters used in such networks may not produce precise probabilities of interest without having to introduce drastic assumptions, we also carry out a perturbation analysis with respect to these parameters. Using techniques from interval arithmetic, we can deliver sharp bounds for the true uncertainity effect. The latter is very important because the packet loss probability function can be very sensitive to relatively small changes in the network parameters. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Parallel Adaptive Multilevel Methods with Full Domain Partitions
Authors: Mitchell William F.
Published: March 2004

Adaptive multilevel methods are methods for solving partial differential equations that combine adaptive grid refinement with multigrid solution techniques. These methods have been shown to be very effective on sequential computers. Recently, a technique for parallelizing these methods for cluster computers has been developed. This paper presents an overview of a particular adaptive multilevel method and the parallelization of that method via the full domain partition. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Exponentially‐fitted algorithms: fixed or frequency dependent knot points?
Authors: Vanden Berghe G. , Van Daele M. , Vande Vyver H.
Published: March 2004

Exponentially‐fitted algorithms are constructed for the derivation of Gauss formulae and implicit Runge‐Kutta methods of collocation type making them tuned for oscillatory (or exponential) functions. The weights and the abscissas of these formulae can depend naturally on the frequency ω by the very construction. For twopoints Gauss formulae and two‐step Runge‐Kutta methods a detailed study of the obtained results is made. In particular the difference in the numerical application of these algorithms with fixed points and/or frequency dependent nodes is analysed. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fitting circular arcs by orthogonal distance regression
Authors: Atieg A. , Watson G. A.
Published: March 2004

The problem is considered of fitting circular arcs to discrete data using orthogonal distance regression. This can be formulated as a constrained nonlinear least squares problem, and an efficient Gauss‐Newton method is developed. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mean Square Stability of a Class of Runge‐Kutta Methods for 2‐Dimensional Stochastic Differential Systems
Authors: Abukhaled Marwan I.
Published: March 2004

Despite the intensive work done on developing numerical schemes for stochastic differential equations, stability analysis of these schemes when applied to stochastic differential systems is still under premature stage. Motivated by the work of Saito and Mitsui in [11], we investigate mean square stability for a class of weak second order Runge‐Kutta schemes applied to 2‐dimensional stochastic differential systems. Stability criteria will be established, and numerical examples in support of the theoretical analysis will be provided. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Finite difference time domain simulation of soil ionization in grounding systems under lightning surge conditions
Authors: Ala G. , Francomano E. , Toscano E. , Viola F.
Published: March 2004

This paper proposes a Maxwell's equations finite difference time domain (FDTD) approach for electromagnetic transients in ground electrodes in order to take into account the non linear effects due to soil ionization. A time variable soil resistivity method is used in order to simulate the soil breakdown, without the formulation of an initial hypothesis about the geometrical shape of the ionized zone around the electrodes. The model has been validated by comparing the computed results with available data found in technical literature referred to concentrated earths. Some application examples referred to complex grounding systems are reported to show the computational capability of the proposed model. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An advanced variant of an interpolatory graphical display algorithm
Authors: Ala G. , Francomano E. , Tortorici A. , Toscano E. , Viola F.
Published: March 2004

In this paper an advanced interpolatory graphical display algorithm based on cardinal B‐spline functions is provided. It is well‐known that B‐spline functions are a flexible tool to design various scale rapresentations of a signal. The proposed method allows to display without recursion a function at any desiderable resolution so that only initial data and opportune vectors weight are involved. In this way the structure of the algorithm is independent across the scale and a computational efficiency is reached. In this paper mono and bi‐dimensional vectors weight generated by means of centered cubic cardinal B‐spline functions have been supplied. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characteristic directions approach to solving scalar one‐dimensional nonlinear advection equation with non‐convex flow function
Authors: Bokov D. N.
Published: March 2004

A concept of the characteristic technique used to obtain a generalized solution of the scalar one‐dimensional nonlinear advection equation with the non‐convex flow function is presented. Two grids: characteristic and Eulerian are used to obtain numerical solution. A characteristic grid is adaptive both to the properties of the initial distribution function and to the properties of the boundary condition function. This allows: development of the algorithm for obtaining a numerical solution on characteristic grid using the properties of the solution of nonlinear advection equation in smooth region; to reproduce spatial location and solution value at the discontinuity points and extreme points at the accuracy determined by interpolation and approximation of initial values and boundary condition functions. For the non‐convex flow function, algorithms are proposed for the definition of the sequence of Riemann problems (strong discontinuity) and for their solving. Refined expressions are derived for the velocity of a strong non‐stationary discontinuity. Construction of the solution with satisfying of integral preservation law for the non‐convex flow function is presented. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparison of Least Squares FEM, Mixed Galerkin FEM and an Implicit FDM Applied to Acoustic Scattering
Authors: Cadenas Carlos E. , Villamizar Vianey
Published: March 2004

This paper compares the performances of a least squares finite element method (LSFEM), a mixed Galerkin finite element method (MGFEM), and an implicit finite difference method (IFDM), when they are applied to an acoustic scattering problem modelled by the one‐dimensional Helmholtz equation. First, the boundary value problem is written as a first order system of differential equations, and variational formulations for the LSFEM and MGFEM are derived. Then, by using appropriate basis functions, the stiffness matrices and load vectors which define the corresponding linear algebraic systems are obtained. In all cases, the stiffness matrix is banded and for the LSFEM it is also Hermitian. Numerical tests show that all these methods have quadratic convergence to the exact solution. However, their efficiency assessed in terms of the number of nodes and computing time required to reach quadratic convergence varies. It is observed that LSFEM requires many more nodes and employs much more time than MGFEM and IFDM to reach the quadratic convergence for high frequencies. It is also found that MGFEM has less numerical dispersion and, as a consequence, performs better than IFDM and LSFEM for high frequencies. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Constraint Reasoning with Differential Equations
Authors: Cruz Jorge , Barahona Pedro
Published: March 2004

System dynamics is naturally expressed by means of differential equations. Despite their expressive power, they are difficult to reason about and to make decisions upon, given their non‐linearity and the important effects that the uncertainty on data may cause. In contrast with traditional numerical simulations that may only provide a likelihood of the results obtained, we propose a constraint reasoning framework that enables safe decision support despite data uncertainty. The approach is illustrated in the tuning of drug design and in an epidemiological study. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Preconditioned Finite Element Method for the p‐Laplacian Parabolic Equation
Authors: Gerace I. , Pucci P. , Ceccarelli N. , Discepoli M. , Mariani R.
Published: March 2004

In this paper we propose a method for the discretization of the parabolic p‐Laplacian equation. In particular we use alternately either the backward Euler scheme or the Crank‐Nicolson scheme for the time‐discretization and the first order Finite Element Method for space‐discretization as in [7]. To obtain the numerical solution we have to invert a block Toeplitz matrix with Toeplitz blocks. To this aim we use a Conjugate Gradient (CG) algorithm preconditioned by a block circulant matrix with circulant blocks. A Two‐Dimensional Discrete Fast Sine‐Cosine Transform (2D‐DFSCT) is applied to invert the block circulant matrix with circulant blocks. The experimental results show how the application of the preconditioner reduces the iterations of the CG algorithm of about the 56% –75%. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Iteratively Weighted Approximation Algorithms For Nonlinear Problems Using Radial Basis Function Examples
Authors: Jenkinson D. P. , Mason J. C. , Crampton A.
Published: March 2004

A set of discrete data (xk, f (xk)) (k = 1, 2, …, m) may be fitted in any lp norm by a nonlinear form derived from a function g (L) of a linear form L = L(x). Such a nonlinear approximation problem may under appropriate conditions be (asymptotically) replaced by the fitting of g–1 (f) by L in any lp norm with respect to a weight function w = g′ (g–1 (f)). In practice this “direct method” can yield very good results, sometimes coming close to a best approximation. However, to ensure a near‐best approximation, by using an iterative procedure based on fitting L, two algorithms are proposed in the l2 norm ‐ one already established by Mason and Upton (1989) and one completely new, based on minimising the two algorithms and multiplicative combinations of errors, respectively. For a general g we prove they converge locally and linearly with small constants. Moreover it is established that they converge to different (nonlinear) “Galerkin type” approximations, the first based on making the explicit error ϵ ≡ f – g (L) orthogonal to a set of functions forming a basis for L, and the second based on making the implicit error ϵ* ≡ w(g–1 (f) – L) orthogonal to such a basis. Finally, and mainly for comparison purposes, the well known Gauss‐Newton algorithm is adopted for the determination of a best (nonlinear) approximation. Illustrative problems are tackled and numerical results show how effective all of the algorithms can be. To add a further novel feature, L is here chosen throughout to be a radial basis function (RBF), and, as far as we are aware, this is one of the first successful uses of a (nonlinear) function of an RBF as an approximation form in data fitting. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Weighted Upwinding Finite Volume Method for the Convection Diffusion Problem on a Nonstandard Covolume Grid
Authors: Liang Dong , Zhao Weidong
Published: March 2004

In this paper we propose a weighted upwinding finite volume method on a nonstandard covolume grid for the variable coefficient convection‐diffusion problems. We give a simple method of choosing the optimal weighted factors depending on the local Peclet's numbers of the original problem. With the optimal factors the method overcomes numerical oscillation and avoids the numerical dispersion and has high‐order computing accuracy. The conservation law and the maximum principle are proved. The second‐order error estimates in L2 and discrete H1 norms are obtained for the optimal weighted upwinding finite volume method. Numerical experiments are given to illustrate the performance of the method. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical Solution of the two‐dimensional time independent Schrödinger Equation by symplectic schemes
Authors: Monovasilis Th. , Kalogiratou Z. , Simos T. E.
Published: March 2004

The solution of the two‐dimensional time‐independent Schrödinger equation is considered by partial discretization. The discretized problem is treated as an ordinary differential equation problem and solved numerically by asymptotically symplectic methods. The problem is then transformed into an algebraic eigenvalue problem involving real, symmetric matrices. The eigenvalues of the two‐dimensional harmonic oscillator and the twodimensional Henon‐Heils potential are computed by the application of the methods developed. The results are compared with the results produced by full discretization. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effective Numerical Approximation of Schrödinger type Equations through Multiderivative Exponentially‐fitted Schemes
Authors: Psihoyios G. , Simos T. E.
Published: March 2004

In this paper an exponentially‐fitted multiderivative method is developed for the numerical integration of the Schrödinger equation. We call the method multi‐derivative since it uses derivatives of orders two and four. An application to the resonance problem of the radial Schrödinger equation indicates that the new method is more efficient than the Numerov method and other known methods found in the literature. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Efficient Numerical Solution of Orbital Problems with the use of Symmetric Four‐step Trigonometrically‐fitted Methods
Authors: Psihoyios G. , Simos T. E.
Published: March 2004

An explicit hybrid symmetric four‐step method of algebraic order six is developed in this paper. Numerical comparative results from the application of the new method to well known periodic orbital problems, demonstrate the efficiency of the method presented here. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Difference schemes for the class of singularly perturbed boundary value problems
Authors: Rafatov Ismail R. , Sklyar Sergey N.
Published: March 2004

This work deals with the construction of difference schemes for the numerical solution of singularly perturbed boundary value problems, which appear while solving heat transfer equations with spherical symmetry. The projective version of integral interpolation (PVIIM) method is used. Derived schemes allow to approximate the solution of the problem and the derivatives of the solution at the same time. Moreover, they allow to approximate the boundary conditions of general form in the framework of the same method. New schemes are tested in order to compare them with well known difference schemes. Estimates for rates of classical and uniform convergence are carried out. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimally Controlled Dynamics of One Dimensional Harmonic Oscillator: Linear Dipole Function and Quadratic Penalty
Authors: Tunga Burcu , Demiralp Metin
Published: March 2004

This work deals with the optimal control of one dimensional quantum harmonic oscillator under an external field characterized by a linear dipole function. The penalty term is taken as kinetic energy. The objective operator whose expectation value is desired to get a prescribed target value is taken as the square of the position operator. The dipole function hypothesis in the external field is valid only for weak fields otherwise hyperpolarizability terms which contain powers of the field amplitude higher than 1 should be considered. The weak field assumption enables us to develop a first order perturbation approach to get approximate solutions to the wave and costate equations. These solutions contain the field amplitude and another unknown, so‐called deviation constant, through some certain integrals. By inserting these expressions into the connection equation which functionally relates the field amplitude to the wave and costate function it is possible to produce an integral equation. Same manipulations on the objective equation results in an algebraic equation to determine the deviation parameter. The algebraic deviation equation produces incompatibility which can be relaxed by including second order perturbative term of wave function. The integral and algebraic equations mentioned above are asymptotically solved. Their global solutions are left to future works since the main purpose of this work is to obtain the so‐called field and deviation equations. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)