bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetic hysteresis loop tuning in antiferromagnetically coupled bilayer structures
Authors: Berger A. , Margulies D. T. , Do H.
Published: August 2004

We have utilized antiferromagnetically coupled bilayer structures to magnetically tune hysteresis loop properties. A key element of this approach is the nonoverlapping switching field distribution of the two magnetic layers. This allows measurement of the magnetization reversal in the soft-magnetic layer (SL) at low fields without perturbing the magnetic state of the hard-magnetic layer (HL). The magnetization of HL can be changed by an appropriate high-field sequence, which also modifies the effective disorder level in SL due to the antiferromagnetic interlayer coupling. Variations of the SL hysteresis loop squareness by a factor of up to 50 are reported by utilizing this fully reversible tuning procedure.
Electron trapping at the Si (111) atomic step edge
Authors: Ishii Masashi , Hamilton Bruce
Published: August 2004

We have investigated the charge distribution at the interface between the Si (111) wafer and its native oxide by Kelvin force microscopy (KFM) with excitation from a He–Cd laser source. Simultaneous imaging using KFM and atomic force microscopy revealed preferential electron trapping at the Si atomic step edge. No electron hopping (>3.5nm radius) to neighboring trapping centers was observed. We also found that the ultraviolet laser irradiation enhanced the electron trapping. The trapping probability under visible laser irradiation and that without irradiation were almost the same, viz. ∼40% of that under ultraviolet irradiation. These findings are explained in terms of incomplete bond termination.
Numerical analysis of the spin-dependent dark current in microcrystalline silicon solar cells
Authors: Brammer T. , Stiebig H. , Lips K.
Published: August 2004

We present a detailed analysis of the voltage dependence of dangling bond recombination in microcrystalline silicon p-i-n diodes observed in the forward dark current at room temperature by electrically detected magnetic resonance (EDMR). The EDMR response is numerically simulated with physically reasonable parameters that are well suited to fully describe the electronic behavior of the diodes. A sign reversal as observed for amorphous silicon diodes is predicted at high voltages. The basic mechanism causing the sign reversal is shown to be due to space charge. The high sensitivity of the EDMR response to various material parameters is demonstrated.
On the energetic origin of self-limiting trenches formed around Ge∕Si quantum dots
Authors: Tambe D. T. , Shenoy V. B.
Published: August 2004

At high growth temperatures, the misfit strain at the boundary of Ge quantum dots on Si(001) is relieved by formation of trenches around the base of the islands. The depth of the trenches has been observed to saturate at a level that scales linearly with the base-width of the islands. Using finite element simulations, we show that this self-limiting behavior is consistent with the energetics of trench formation that involves a competition between the relaxation of the strain energy at the base of the island and the energy cost for creating the trench surface. The close quantitative agreement of the computed trench depths with the experimental measurements of Chaparro et al. [Appl. Phys. Lett. 76, 3534 (2000)] suggests an energetic rather than kinetic origin for the observed saturation behavior.
A microfabricated atomic clock
Authors: Knappe Svenja , Shah Vishal , Schwindt Peter D. D. , Hollberg Leo , Kitching John , Liew Li-Anne , Moreland John
Published: August 2004

Fabrication techniques usually applied to microelectromechanical systems (MEMS) are used to reduce the size and operating power of the core physics assembly of an atomic clock. With a volume of 9.5mm3, a fractional frequency instability of 2.5×10−10 at 1s of integration, and dissipating less than 75mW of power, the device has the potential to bring atomically precise timing to hand-held, battery-operated devices. In addition, the design and fabrication process allows for wafer-level assembly of the structures, enabling low-cost mass-production of thousands of identical units with the same process sequence, and easy integration with other electronics.
Exchange biasing of the ferromagnetic semiconductor Ga1−xMnxAs
Authors: Eid K. F. , Stone M. B. , Ku K. C. , Maksimov O. , Schiffer P. , Samarth N. , Shih T. C. , Palmstrøm C. J.
Published: August 2004

We demonstrate the exchange coupling of a ferromagnetic semiconductor (Ga1−xMnxAs) with an overgrown antiferromagnet (MnO). Unlike most conventional exchange biased systems, the blocking temperature of the antiferromagnet (TB=48±2K) and the Curie temperature of the ferromagnet (TC=55.1±0.2K) are comparable. The resulting exchange bias manifests itself as a clear shift in the magnetization hysteresis loop when the bilayer is cooled in the presence of an applied magnetic field and an enhancement of the coercive field.
Laser-assisted photothermal imprinting of nanocomposite
Authors: Lu Y. , Shao D. B. , Chen S. C.
Published: August 2004

We report on a laser-assisted photothermal imprinting method for directly patterning carbon nanofiber-reinforced polyethylene nanocomposite. A single laser pulse from a solid state Nd:YAG laser (10ns pluse, 532 and 355nm wavelengths) is used to melt/soften a thin skin layer of the polymer nanocomposite. Meanwhile, a fused quartz mold with micro sized surface relief structures is pressed against the surface of the composite. Successful pattern transfer is realized upon releasing the quartz mold. Although polyethylene is transparent to the laser beam, the carbon nanofibers in the high density polyethylene (HDPE) matrix absorb the laser energy and convert it into heat. Numerical heat conduction simulation shows the HDPE matrix is partially melted or softened, allowing for easier imprinting of the relief pattern of the quartz mold.
Resonant dipole antennas for continuous-wave terahertz photomixers
Authors: Gregory I. S. , Tribe W. R. , Cole B. E. , Evans M. J. , Linfield E. H. , Davies A. G. , Missous M.
Published: August 2004

We present measurements and numerical simulations for the performance of resonant dipole antennas used in continuous-wave terahertz photomixers. We demonstrate that center-feed dipoles, with inductively choked electrical feeds, are a good choice for a resonant emitter design, and outperform broadband spiral antennas by a factor of five at a resonant frequency of 0.4THz. Excellent agreement is found between experiment and the predictions of finite element simulations. Furthermore, we show that the dipoles can outperform spirals across frequency bands of over 0.5THz, opening the way for their use in terahertz spectroscopy.
A hairpin turn in a class II MHC-bound peptide orients residues outside the binding groove for T cell recognition
Authors: Zavala-Ruiz Zarixia , Strug Iwona , Walker Bruce D. , Norris Philip J. , Stern Lawrence J.
Published: August 2004

T cells generally recognize peptide antigens bound to MHC proteins through contacts with residues found within or immediately flanking the seven- to nine-residue sequence accommodated in the MHC peptide-binding groove. However, some T cells require peptide residues outside this region for activation, the structural basis for which is unknown. Here, we have investigated a HIV Gag-specific T cell clone that requires an unusually long peptide antigen for activation. The crystal structure of a minimally antigenic 16-mer bound to HLA-DR1 shows that the peptide C-terminal region bends sharply into a hairpin turn as it exits the binding site, orienting peptide residues outside the MHC-binding region in position to interact with a T cell receptor. Peptide truncation and substitution studies show that both the hairpin turn and the extreme C-terminal residues are required for T cell activation. These results demonstrate a previously unrecognized mode of MHC-peptide-T cell receptor interaction.
Large-scale sequencing of the CD33-related Siglec gene cluster in five mammalian species reveals rapid evolution by multiple mechanisms
Authors: Angata Takashi , Margulies Elliott H. , Green Eric D. , Varki Ajit
Published: August 2004

Siglecs are a recently discovered family of animal lectins that belong to the Ig superfamily and recognize sialic acids (Sias). CD33-related Siglecs (CD33rSiglecs) are a subgroup with as-yet-unknown functions, characterized by sequence homology, expression on innate immune cells, conserved cytosolic tyrosine-based signaling motifs, and a clustered localization of their genes. To better understand the biology and evolution of CD33rSiglecs, we sequenced and compared the CD33rSiglec gene cluster from multiple mammalian species. Within the sequenced region, the segments containing CD33rSiglec genes showed a lower degree of sequence conservation. In contrast to the adjacent conserved kallikrein-like genes, the CD33rSiglec genes showed extensive species differences, including expansions of gene subsets; gene deletions, including one human-specific loss of a novel functional primate Siglec (Siglec-13); exon shuffling, generating hybrid genes; accelerated accumulation of nonsynonymous substitutions in the Sia-recognition domain; and multiple instances of mutations of an arginine residue essential for Sia recognition in otherwise intact Siglecs. Nonsynonymous differences between human and chimpanzee orthologs showed uneven distribution between the two β sheets of the Sia-recognition domain, suggesting biased mutation accumulation. These data indicate that CD33rSiglec genes are undergoing rapid evolution via multiple genetic mechanisms, possibly due to an evolutionary “arms race” between hosts and pathogens involving Sia recognition. These studies, which reflect one of the most complete comparative sequence analyses of a rapidly evolving gene cluster, provide a clearer picture of the ortholog status of CD33rSiglecs among primates and rodents and also facilitate rational recommendations regarding their nomenclature.
Dual effect of CD4+CD25+regulatory T cells in neurodegeneration: A dialogue with microglia
Authors: Kipnis Jonathan , Avidan Hila , Caspi Rachel R. , Schwartz Michal
Published: August 2004

Autoimmune CD4+T cells can mediate the ability to withstand neurodegenerative conditions. Here we show that the ability to spontaneously manifest a T cell-dependent protective response is restricted by naturally occurring CD4+CD25+regulatory T cells (Treg); depletion of Treg was beneficial in two mouse strains (C57BL/6J and BALB/c/OLA) differing in their spontaneous T cell-dependent ability to withstand the consequences of optic nerve injury. Passive transfer of exogenous Treg was destructive in BALB/c/OLA mice (which can spontaneously manifest a T cell-dependent protective anti-self response to injury) but beneficial in C57BL/6J mice (which have only limited ability to manifest such a response). This dichotomy was resolved by the finding that, in severe combined immunodeficient mice, a beneficial effect is obtained by passive transfer of either Treg-free CD4+T cells (Teff) or Treg alone, indicating that neuroprotection can be achieved by either Treg or Teff in the absence of the other. We attribute these disparate effects of Treg to their differential interaction (in part via IL-10 and transforming growth factor β) with local innate immune cells (microglia) in the presence and in the absence of effector T cells. Activation of microglia by pro- and antiinflammatory cytokines in suitably controlled amounts might trigger different signal transduction pathways, each of which induces a neuroprotective microglial phenotype. These results suggest that, under neurodegenerative conditions, the effects of Treg, and possibly also of other regulatory T cells, might not be uniform, and that their expression in different individuals might be genetically determined. Therefore, therapeutic intervention based on induction of regulatory T cells might have limitations.
Anticorrelated motions as a driving force in enzyme catalysis: The dehydrogenase reaction
Authors: Luo Jia , Bruice Thomas C.
Published: August 2004

Molecular dynamics and cross-correlation analysis of the horse liver alcohol dehydrogenase HLADH·NAD
+
·PhCH
2
O
–
complex has established anticorrelated motions between the NAD
+
-binding domain and other portions of the enzyme. Four pairs of anticorrelated interactions are (
i
and
ii
) cofactor-binding domain: C
α
of V292 and the CG1 of V203 with C7 of PhCH
2
O
–
; (
iii
) cofactor-binding domain: amide carbonyl oxygen of I318 with amide N of H67; and (
iv
) cofactor domain: C
α
of T178 with carbonyl oxygen of L141. The average distances between pairs are 9.2 Å for
i
, 8.2 Å for
ii
, 14.7 Å for
iii
, and 18.2 Å for
iv
. The motions of
i
and
ii
are most important in the ≈0.5 Å pushing of C4 of NAD
+
toward C7 of PhCH
2
O
–
to form push near-attack conformer (NACs). The motions of
iv
are less so, and those of
iii
are not important. Seventy-five quantum mechanics/molecular mechanics calculations of the energies of reaction were carried out without structural restrictions from different stages of the molecular dynamics trajectory. Of the 71 conformations, the 29 fulfilling NAC criteria were associated with the lowest energies of activation. Thus, anticorrelated motions from the NAD
+
-binding domain by way of the neighboring V292 and V203 have a pushing motion, which moves the C4 of NAD
+
toward the H–C7 of the substrate. Longer-range anticorrelated motions involving the cofactor-binding domain have no or very little influence on NAC formation.
Development of an enhanced needle and syringe programme: the First Step programme pilot
Authors: HUDOBA MICHELLE , GRENYER BRIN F. S. , O'TOOLE MIRIAM
Published: August 2004

The First Step programme is a new approach to needle and syringe exchange services established to help intravenous drug users reduce harmful drug use behaviours, provide psychoeducation and act as a point of transition enhancing access to other health and community services. The First Step assertive treatment approach was implemented in a medium‐sized community area health service and evaluated over an 18‐month period. A pilot evaluation of staff training was also conducted, demonstrating a significant improvement in staff skills in assertive outreach, needs assessment, engagement, psychoeducation and referral. Measures of drug‐related harm showed the benefits of new early engagement‐enhancing psychoeducational interventions, with increases in needles distributed and returned and greater referrals to drug and alcohol and other health services. Training needle and syringe workers towards a more assertive community outreach role gives them the ability to provide psychoeducation and harm minimization strategies and act as a conduit for intravenous drug users to enter treatment.
A pilot study of buprenorphine—naloxone combination tablet (Suboxone®) in treatment of opioid dependence
Authors: BELL JAMES , BYRON GAYE , GIBSON AMY , MORRIS AMANDA
Published: August 2004

In Australia, maintenance treatment for opioid dependence involves supervised daily administration of a dose of methadone or buprenorphine. A sublingual tablet combining buprenorphine and naloxone in a 4: 1 ratio (Suboxone™) has been developed, designed to deter diversion and intravenous misuse, and may be suitable for unsupervised administration. The aim of this study was to investigate the tolerability of Suboxone, and investigate whether unsupervised administration can be effective in stabilized patients. Employed patients on buprenorphine maintenance, who had ceased heroin use, were switched to Suboxone and provided with weekly supplies of medication to take without supervised administration. Subjects were monitored closely with weekly clinical reviews, and research interviews at baseline, 3 and 6 months. Only 11% of people receiving buprenorphine met eligibility criteria. Seventeen subjects were recruited. Fifteen were retained for the full 6 months. No subject appeared destabilized by unsupervised dosing. Suboxone was well tolerated. The current trial demonstrated that unsupervised administration with regular clinical monitoring can be effective in selected patients. However, using access to unsupervised dosing to promote abstinence from heroin probably limits the potential benefits of unsupervised administration to a very small proportion of patients.
‘An unacceptable risk’: the problem of alcoholic milk
Authors: MUNRO GEOFFREY , LEARMONTH ANNE
Published: August 2004

In 2002 Wicked Holdings Pty Ltd, a company formed for the purpose of marketing alcoholic milk, applied to the Director of Liquor Licensing Victoria (LLV) for a wholesale licence to distribute a beverage known as ‘Moo Joose’. This article outlines the case against alcoholic milk as the ultimate ‘alcopop’. The argument encompasses the risk that alcoholic milk would reinforce and increase existing levels of under‐age drinking in Australia, the risk it would reduce the age of initiation into drinking and the potential for alcoholic milk to be mistaken for a ‘healthy’ version of alcohol and a ‘safe’ alcoholic beverage. When LLV refused the application for a licence, Wicked Holdings appealed to the Victorian Civil and Administrative Tribunal. Following a public hearing the Tribunal confirmed LLV's decision to refuse a licence on the grounds the product posed an unacceptable risk to the health and well‐being of young people.
Rabbit Ear Cartilage Regeneration With a Small Intestinal Submucosa Graft
Authors: Pribitkin Edmund A. , Ambro Bryan T. , Bloeden Esa , O'Hara Brian J.
Published: August 2004

Objectives/Hypothesis: The objective was to demonstrate that interpositional grafting with porcine small intestinal submucosa promotes cartilage regeneration following excision of rabbit auricular cartilage.

Study Design: Blinded, controlled study.

Methods: Eight New Zealand white rabbits underwent excision of auricular cartilage on two sites with and two sites without preservation of perichondrium. Porcine small intestinal submucosa was implanted into one site with and one site without intact perichondrium. Remaining sites served as control sites. Histological assessment was performed at 3 (n = 4) and 6 (n = 3) months and at 1 year (n = 1) after grafting.

Results: Histological evaluation showed cartilage regeneration accompanied by chronic inflammation in areas in which porcine small intestinal submucosa was implanted between layers of intact perichondrium. Other sites failed to show significant cartilage regeneration.

Conclusion: The results of the study using porcine small intestinal submucosa as a bioscaffold for cartilage regeneration are promising and justify further animal and human studies.
Penalized Partial Likelihood for Frailties and Smoothing Splines in Time to First Insemination Models for Dairy Cows
Authors: Duchateau Luc , Janssen Paul
Published: August 2004

SummaryIn many epidemiological studies time to event data are clustered and the physiological relationship between (time‐dependent) covariates and the log hazard is often not linear as assumed in the Cox model. Introducing frailties in the Cox model can account for the clustering of the data and smoothing splines can be used to describe nonlinear relations. These two extensions of the Cox model are introduced jointly and it is shown how penalized partial likelihood techniques can be used to fit the extended model. We demonstrate the need for such a model to study the relation between the physiological covariates milk ureum and protein concentration and the log hazard of first insemination in dairy cows, with the farms as clusters.
Regression Analysis of Doubly Censored Failure Time Data Using the Additive Hazards Model
Authors: Sun Liuquan , Kim Yang‐jin , Sun Jianguo
Published: August 2004

Summary Doubly censored failure time data arise when the survival time of interest is the elapsed time between two related events and observations on occurrences of both events could be censored. Regression analysis of doubly censored data has recently attracted considerable attention and for this a few methods have been proposed (Kim et al., 1993, Biometrics49, 13–22; Sun et al., 1999, Biometrics55, 909–914; Pan, 2001, Biometrics57, 1245–1250). However, all of the methods are based on the proportional hazards model and it is well known that the proportional hazards model may not fit failure time data well sometimes. This article investigates regression analysis of such data using the additive hazards model and an estimating equation approach is proposed for inference about regression parameters of interest. The proposed method can be easily implemented and the properties of the proposed estimates of regression parameters are established. The method is applied to a set of doubly censored data from an AIDS cohort study.
Estimating the Cumulative Risk of a False‐Positive Test in a Repeated Screening Program
Authors: Xu Jian‐Lun , Fagerstrom Richard M. , Prorok Philip C. , Kramer Barnett S.
Published: August 2004

Summary The goal of screening tests for a chronic disease such as cancer is early detection and treatment with a consequent reduction in mortality from the disease. Screening tests, however, might produce false positive and false‐negative results. With an increasing number of screening tests, it is clear that the risk of a false‐positive screen, a finding with potentially significant emotional, financial, and health costs, also increases. Elmore et al. (1998, New England Journal of Medicine338, 1089–1096), Christiansen et al. (2000, Journal of the National Cancer Institute92, 1657–1666), and Gelfand and Wang (2000, Statistics in Medicine19, 1865–1879) investigated this problem under the somewhat unrealistic assumption that the choice of making the decision to drop out at the kth screen does not depend upon the results of the earlier k− 1 screens. In this article we obtain sufficient and necessary conditions for their assumption to hold and use one of them to provide a method for testing the validity of the assumption. A new model which does not depend on their assumption is introduced. The maximum likelihood estimator of the cumulative risk of receiving a false‐positive screen under the new model is derived and its asymptotic normality is proved. The extension of the new model by incorporating covariate information is also considered. We apply our testing method and the new model to data from the breast cancer screening trial of the Health Insurance Plan of Greater New York.
Estimation of Growth Parameters from Multiple‐Recapture Data
Authors: Wang You‐Gan
Published: August 2004

SummaryThis article develops a method for analysis of growth data with multiple recaptures when the initial ages forallindividuals are unknown. The existing approaches either impute the initial ages or model them as random effects. Assumptions about the initial age are not verifiable because all the initial ages are unknown. We present an alternative approach that treats all the lengths including the length at first capture as correlated repeated measures for each individual. Optimal estimating equations are developed using the generalized estimating equations approach that only requires the first two moment assumptions. Explicit expressions for estimation of both mean growth parameters and variance components are given to minimize the computational complexity. Simulation studies indicate that the proposed method works well. Two real data sets are analyzed for illustration, one from whelks (Dicathais aegaota) and the other from southern rock lobster (Jasus edwardsii) in South Australia.
Optimal Conditional Error Functions for the Control of Conditional Power
Authors: Brannath Werner , Bauer Peter
Published: August 2004

Summary Ethical considerations and the competitive environment of clinical trials usually require that any given trial have sufficient power to detect a treatment advance. If at an interim analysis the available data are used to decide whether the trial is promising enough to be continued, investigators and sponsors often wish to have a high conditional power, which is the probability to reject the null hypothesis given the interim data and the alternative of interest. Under this requirement a design with interim sample size recalculation, which keeps the overall and conditional power at a prespecified value and preserves the overall type I error rate, is a reasonable alternative to a classical group sequential design, in which the conditional power is often too small. In this article two‐stage designs with control of overall and conditional power are constructed that minimize the expected sample size, either for a simple point alternative or for a random mixture of alternatives given by a prior density for the efficacy parameter. The presented optimality result applies to trials with and without an interim hypothesis test; in addition, one can account for constraints such as a minimal sample size for the second stage. The optimal designs will be illustrated with an example, and will be compared to the frequently considered method of using the conditional type I error level of a group sequential design.
Multiple‐Testing Strategy for Analyzing cDNA Array Data on Gene Expression
Authors: Delongchamp Robert R. , Bowyer John F. , Chen James J. , Kodell Ralph L.
Published: August 2004

Summary An objective of many functional genomics studies is to estimate treatment‐induced changes in gene expression. cDNA arrays interrogate each tissue sample for the levels of mRNA for hundreds to tens of thousands of genes, and the use of this technology leads to a multitude of treatment contrasts. By‐gene hypotheses tests evaluate the evidence supporting no effect, but selecting a significance level requires dealing with the multitude of comparisons. The p‐values from these tests order the genes such that a p‐value cutoff divides the genes into two sets. Ideally one set would contain the affected genes and the other would contain the unaffected genes. However, the set of genes selected as affected will have false positives, i.e., genes that are not affected by treatment. Likewise, the other set of genes, selected as unaffected, will contain false negatives, i.e., genes that are affected. A plot of the observed p‐values (1 −p) versus their expectation under a uniform [0, 1] distribution allows one to estimate the number of true null hypotheses. With this estimate, the false positive rates and false negative rates associated with any p‐value cutoff can be estimated. When computed for a range of cutoffs, these rates summarize the ability of the study to resolve effects. In our work, we are more interested in selecting most of the affected genes rather than protecting against a few false positives. An optimum cutoff, i.e., the best set given the data, depends upon the relative cost of falsely classifying a gene as affected versus the cost of falsely classifying a gene as unaffected. We select the cutoff by a decision‐theoretic method analogous to methods developed for receiver operating characteristic curves. In addition, we estimate the false discovery rate and the false nondiscovery rate associated with any cutoff value. Two functional genomics studies that were designed to assess a treatment effect are used to illustrate how the methods allowed the investigators to determine a cutoff to suit their research goals.
Alongshore dispersal and site fidelity of juvenile plaice from tagging and transplants
Authors: Burrows M. T. , Gibson R. N. , Robb L. , Maclean A.
Published: August 2004

Juvenile plaice Pleuronectes platessa(n = 1281) were tagged and released at two locations 300 m apart on a 1 km long sandy beach. Most (>90%) of the fish were recaptured within 100 m of the release site (shown by the colour of the tag), with very few caught >200 m distance after 6 weeks. The changing spatial distribution of marked fish was adequately reproduced by a simple dispersal model with a single parameter: a 78% probability of remaining in a 100 m wide zone from one day to the next, with a 22% chance that fish move into an adjacent zone. In a subsequent similar study at the same beach, fish were either released at the point of capture (n = 881) or transplanted to the alternate site (n = 910) 100 m distant. After 6 weeks, transplanted fish moved along the shore towards their sites of original capture. Fish replaced at the point of capture showed no such movement along the shore. Further modification of the dispersal model to allow for a distinction between dispersal from home sites and from sites away from the original point of collection, was sufficient to reproduce the behaviour of the populations of both transplanted and control treatment groups. The likelihood of dispersal from home sites was much less than that seen at sites away from home. Juvenile plaice thus have a degree of long‐shore site fidelity not expected of a fish with strong depth‐related migration behaviour in a relatively homogenous habitat.
Hypoxia and interdemic variation in Poecilia latipinna
Authors: Timmerman C. M. , Chapman L. J.
Published: August 2004

Variation in respiratory traits was quantified between two populations of the sailfin molly Poecilia latipinna(one from a periodically hypoxic salt marsh, Cedar Key, and one from a chronically normoxic river site, Santa Fe River). Two suites of characters were selected: traits that may show both short‐term acclimation response and interdemic variation in acclimation response (metabolic rate, critical oxygen tension and respiratory behaviour), and those that are not likely to respond to short‐term acclimation but may vary among populations (gill morphometric characters). Sailfin mollies from the salt marsh, acclimated to hypoxia (1 mg l−1, c. 20 mmHg) for 6 weeks, spent less time conducting aquatic surface respiration and had lower gill ventilation rates than hypoxia‐acclimated conspecifics from the well‐oxygenated river site. Poecilia latipinna acclimated to hypoxia exhibited a lower critical oxygen tension (Pc) than fish acclimated to normoxia; however, there was also a significant population effect. Poecilia latipinna from Cedar Key exhibited a lower Pc than fish from the Santa Fe River, regardless of acclimation. Cedar Key fish had a 14% higher mean gill surface area relative to fish from the Santa Fe River, a character that could account, at least in part, for their greater tolerance to hypoxia.
Taste buds on the lips and mouth of some blenniid and gobiid fishes: comparative distribution and morphology
Authors: Fishelson L. , Delarea Y.
Published: August 2004

Analysis of taste buds (TB) on the lips and oropharyngeal cavity in several species of gobies (Gobiidae) and blennies (Blenniidae) from the Red Sea, Mediterranean Sea and Seychelles, revealed three types of these organs: types I and II, which protrude above the surrounding epithelium on lobules of various forms, and type III, which terminate on the level of the epithelium. These TB are composed of either light or dark sensory cells with apical microvillar extensions, and of basal cells situated at the TB base. Synaptic junctions occur between the TB cells and the sub‐epithelial sensory nerves. Numerical distribution and morphology of TB on the lips and in the oral cavity of the species studied revealed patterns that are specific on both species and family levels. In most of the gobies the lips, jaws and oral breathing valves are usually covered by numerous lobules, each of which bears papillae with two to seven type I and type II TB, reaching a total of up to 7500 buds on the lips and in the oropharyngeal cavity in these fishes. The number of TB increases with growth (age) of the fish, and the combined and total sensory area of TB in an adult fish can reach up to 80 000 μm2. In contrast, in blennies the anterior region of the oral cavity is seldom lobulated, with far fewer TB; the majority of TB are found in the more posterior region. It is postulated that these differences in TB density and location between gobies and blennies are connected to differences in foraging strategies and diet, and may represent ecomorphological adaptations.
A multi‐metric fish index to assess the environmental condition of estuaries
Authors: Harrison T. D. , Whitfield A. K.
Published: August 2004

The development of a multi‐metric fish index, the Estuarine Fish Community Index (EFCI), for assessing estuarine environments is described. The index comprises 14 metrics or measures that represent four broad fish community attributes: species diversity and composition, species abundance, nursery function and trophic integrity. The individual metrics were evaluated using data that were collected on a South African estuary that was degraded and in which rehabilitation measures were implemented. The evaluation suggested that the selected metrics adequately measure the condition of separate but related components of estuarine fish communities and that these reflect environmental condition. Reference conditions and metric thresholds were derived from fish community data collected during an extensive national study. The final multi‐metric index was then constructed and evaluated. The EFCI combines both structural and functional attributes of estuarine fish communities and integrates these to provide both a robust and sensitive method for assessing the ecological condition of estuarine systems. It is also an effective communication tool for converting ecological information into an easily understood format for managers, policy makers and the general public.
Consumption and gut evacuation rate of laboratory‐reared spotted seatrout (Sciaenidae) larvae and juveniles
Authors: Wuenschel M. J. , Werner R. G.
Published: August 2004

The temperature and mass dependence of maximum consumption rate was measured for larval and early juvenile spotted seatrout Cynoscion nebulosus. Maximum consumption (CMAX) estimates were obtained from feeding and gut evacuation experiments on larvae (3·8–19 mm standard length, LS) at three temperatures (24, 28 and 32° C), and maximum consumption experiments on juveniles at three temperatures (20, 26 and 32° C). Feeding levels were determined for larvae fed live prey (Brachionus plicatilis and Artemia salina)ad libitum. The midgut and total evacuation times were estimated for fish feeding continuously and discontinuously using alternate meals of tagged and untagged live prey. Temperature and fish size had significant effects on gut evacuation and consumption. The gut evacuation time increased with increasing fish size, and decreased with increasing temperatures. Mass‐specific midgut contents increased for small larvae <0·156 mg dry mass (MD)(c. 4 mm LS), and decreased for larger larvae and juveniles. Maximum consumption was modelled by fitting a polynomial function to a reduced dataset of individuals feeding at high levels. The CMAX model predicted an initial increase in specific feeding rate from 70 to 155%MD day−1 for small larvae, before declining for larger larvae and juveniles.
Environmental effects on egg development and hatching success in Jordanella floridae, a species with parental care
Authors: St Mary C. M. , Gordon E. , Hale R. E.
Published: August 2004

Male flagfish Jordanella floridae provide parental care in the form of nest guarding, cleaning and fanning. Patterns of egg development, hatching success and disease in the absence of parental care across a range of physical environments that flagfish naturally experience were observed. Egg hatching success increased with salinity but was unaffected by temperature. Egg development rate, on the other hand, increased with temperature but was unaffected by salinity. Furthermore, disease (most likely fungus on the eggs) was the primary source of mortality. Thus, the results suggest that, in this species, parental care of the eggs can only significantly increase offspring fitness by reducing disease and that the value of care will overall be reduced in saline environments because eggs hatch readily there, in the absence of care.
Digestive enzyme activities in carnivores and herbivores: comparisons among four closely related prickleback fishes (Teleostei: Stichaeidae) from a California rocky intertidal habitat
Authors: Chan A. S. , Horn M. H. , Dickson K. A. , Gawlicka A.
Published: August 2004

Three digestive enzymes in four species of closely related prickleback fishes (family Stichaeidae: Cebidichthys violaceus, Xiphister mucosus, Xiphister atropurpureus and Anoplarchus purpurescens) were analysed to assess whether diet or phylogeny played a larger role in influencing digestive enzyme activity. Cebidichthys violaceus and X. mucosus are primarily herbivorous, whereas X. atropurpureus and A. purpurescens are mainly carnivorous. The two Xiphister species are sister taxa, and A. purpurescens is in a clade adjacent to that of the three other species. Pepsin and trypsin specific activities did not differ significantly among the four species, but α‐amylase activity was significantly higher in the two Xiphister species, followed by C. violaceus, and then A. purpurescens. The wide disparity between the two carnivores, the striking similarity between the two sister taxa, and the significant difference between the two herbivores indicate that activity of α‐amylase follows a pattern influenced more by phylogeny than by diet in these fishes.
Rodlet cells in teleosts: a new insight into their nature and functions
Authors: Manera M. , Dezfuli B. S.
Published: August 2004

The nature of rodlet cells (RCs) and their functions is subject to a number of different interpretations. This review provides a detailed analysis of the parasitic and endogenous origin of these cells. Two new functional aspects of RCs are considered in detail. The possible function of RCs as immune cells was derived from studies that reported an increase in the number of RCs in fish infected with protozoan and metazoan parasites, particularly at the site of the pathogen infection and/or attachment. Accordingly, RCs represent inflammatory cells, with a similar role to eosinophile granule cells, epithelioid cells and mesothelial cells. Rodlet cells may potentially act as biomarkers. Experimental studies that examined the response of RCs in fish exposed to chemical substances such as metals and herbicides reported an increase in the number of RCs in the tissues of the fish. Fish exposed to these substances expressed myelinic figures in the cytoplasm of the RCs and various degrees of rodlet degeneration and high vacuolization of RC cytoplasm were often noticed. Further lines of research are suggested that might elucidate the true function of these enigmatic cells.
Homeowners Insurance With Bundled Catastrophe Coverage
Authors: Grace Martin F. , Klein Robert W. , Kleindorfer Paul R.
Published: August 2004

Abstract

We estimate the demand for homeowners insurance in Florida and New York with indicated loss costs as our proxy for the quantity of real insurance services demanded. We decompose the demand into the demand for coverage of catastrophe perils and the demand for noncatastrophe coverage and estimate these demand functions separately. Our results are relatively consistent in New York and Florida, including evidence that catastrophe demand is more price elastic than noncatastrophe demand. We also find evidence that consumers value options that expand coverage, buy more insurance when it is subsidized through regulatory price constraints, and consider state guaranty fund provisions when purchasing insurance.
Participation in the National Flood Insurance Program: An Empirical Analysis for Coastal Properties
Authors: Kriesel Warren , Landry Craig
Published: August 2004

Abstract

A perennial question about the National Flood Insurance Program is: how can participation be increased? An empirical analysis of individual‐level data reveals that in a sample of coastal areas the participation rate is 49 percent of eligible properties. Participation responsiveness to price is inelastic, but it has been increased by the mandatory purchase requirements for mortgage borrowers. Easing conditions for participation in the program would probably not reduce flood control measures, such as seawalls, which may degrade beach conditions and coastal ecosystems.
Reinsurance Arrangements Maximizing Insurer's Survival Probability
Authors: Gajek Lesław , Zagrodny Dariusz
Published: August 2004

Abstract

The article concerns the problem of purchasing a reinsurance policy that maximizes the survival probability of the insurer. Explicit forms of the contracts optimal for the insurer are derived which are stop loss or truncated stop loss depending on the initial surplus, a quota to be spend on reinsurance and pricing rules of both the insurer and the reinsurer.
On the Cost Structure of the Japanese Property‐Casualty Insurance Industry
Authors: Hirao Yukiko , Inoue Tomoo
Published: August 2004

Abstract

This article tests economies of scale and economies of scope for the property‐casualty insurance companies in Japan. We fit a composite cost function to a set of Japanese firms over the period from 1980 to 1995 and employ an error components model. Our main findings are as follows. First, statistically significant economies of scale are observed in both Japanese firms and foreign firms operating in Japan. Second, economies of scope are also statistically significant for Japanese firms and most of the foreign insurers between the “third sector” products and the rest of the property‐casualty insurance lines.
Phylogeny of the African murid tribe Otomyini (Rodentia), based on morphological and allozyme evidence
Authors: Taylor Peter John , Denys Christiane , Mukerjee Madhupa
Published: August 2004

Based on a cladistic analysis of 45 morphological (craniodental) and 46 binary allozyme characters, previous systematic treatments of the African murid tribe, Otomyini (laminate‐toothed rats), are reviewed. Cladistic analysis of the craniodental data, involving eight outgroup taxa, confirmed the monophyly of the Otomyini, and suggested Pelomys to represent the sister genus of the Otomyini. Craniodental synapomorphies provided strong support for certain basal relationships among Otomyini rodents, reinforcing available palaeontological evidence. However, poor statistical (Bremer decay index) support was obtained for terminal relationships. The data presented revealed a ‘mesic clade’ of southern and eastern African species, with Otomys sloggetti basal to this group. The arid‐adapted, southern Africa‐endemic species, Parotomys littledalei, P. brantsii and O. unisulcatus, were all placed basal to the ‘mesic clade’, but did not form a separate ‘arid clade’, as suggested by earlier biochemical studies. Two allozyme synapomorphies supported the existence of the ‘mesic clade’, separate from arid‐adapted southern African species. A strict cladistic interpretation of the present data did not support the existence of two genera in the tribe, and the two species of Parotomys (whistling rats) should be transferred to Otomys. At the species level, specific identity of O. lacustris and O. barbouri, distinct from O. anchietae, was supported by several autapomorphies, and O. tropicalis burtoni was shown to be included in O. angoniensis rather than O. tropicalis, extending the range of the former species into West Africa.
Phylogeny of the Aplysiidae (Gastropoda, Opisthobranchia) with new aspects of the evolution of seahares
Authors: Klussmann‐Kolb Annette
Published: August 2004

The phylogeny of the Aplysiidae is investigated, based on 37 morphological and histological characters polarized a priori by outgroup comparison. The Aplysiidae represents a monophyletic taxon comprising two distinct clades: Aplysiinae and Dolabellinae + Dolabriferinae + Notarchinae. The traditional classification of Longicommissurata (Aplysiinae + Dolabellinae) is no longer valid since the Longicommissurata are paraphyletic. However, the Brevicommissurata (Dolabriferinae + Notarchinae) form a monophyletic group. Within the Dolabriferinae two sister‐groups can be distinguished:DolabriferaandPhyllaplysia+Petalifera petalifera. The genusPetaliferais paraphyletic. Based on the present phylogeny, several aspects of the evolution of the Aplysiidae are discussed.
First International Phylogenetic Nomenclature Meeting: a report
Authors: Laurin Michel , Cantino Philip D.
Published: August 2004

The First International Phylogenetic Nomenclature Meeting convened in Paris from July 6–9, 2004 in the Muséum National d’Histoire Naturelle. This meeting marked a turning point in the history of biological nomenclature — the inauguration of a new society (the International Society for Phylogenetic Nomenclature) that will soon launch a code of phylogenetic nomenclature (the PhyloCode) that will represent a fundamental change in the way in which taxon names are defined.
Effect of Preexisting Chronic Disease on Primary Cesarean Delivery Rates by Race for Births in U.S. Military Hospitals, 1999–2002
Authors: Linton Andrea , Peterson Michael R.
Published: August 2004

Abstract:  Background: A previous study of the United States Department of Defense healthcare beneficiaries reported elevated cesarean delivery rates for black and Asian women relative to white women that were independent of maternal socioeconomic status. This finding suggests that other maternal factors may explain the elevated rates. The purpose of this study was to examine the prevalence of specific chronic diseases identified as risk factors for complications during pregnancy, labor, and delivery, and to explore the strength of each disease to predict a cesarean outcome. Methods: United States military hospital discharge records from 1999 to 2002 for singleton births to women without a previous cesarean were used to calculate primary cesarean and chronic disease rates for diabetes, hypertension, cardiovascular disease, renal disease, anemia, asthma, sexually transmitted diseases, and substance abuse. Stepwise logistic regression was used to calculate adjusted odds ratios for dichotomized race and chronic disease indicators for five maternal age groups using theχ2difference(p < 0.05) to identify significant variables for inclusion in the model. Primary cesarean delivery rates were then adjusted for the presence of chronic diseases that were significantly associated with a cesarean outcome. Results: Diabetes, genital herpes, and hypertension were significant predictors of cesarean use among all maternal age groups. Cardiovascular disease, renal disease, asthma, and anemia were predictors in some age groups. The remaining disease conditions were not significant predictors for cesarean delivery. Adjustment of cesarean rates for these chronic diseases did not significantly alter the differences in primary cesarean rates for black and Asian mothers relative to white mothers. Conclusions: The presence of certain chronic conditions before pregnancy may increase the likelihood that a woman will deliver by cesarean section. Adjustment of cesarean rates for the presence of these chronic diseases, however, does not account for the difference in cesarean rates observed for white and minority mothers in the study population. The potential for underreporting of chronic diseases complicates a true assessment of the impact of chronic disease on cesarean delivery rate variations between white and minority women.