bluuebunny/crossref_metadata_2025 huggingface dataset:
Autologous blood transfusion in radical hysterectomy
Authors: Pinkerton P. H. , Covens A.
Published: April 2008

Summary. The application of a hospital‐based presurgical autologous blood deposit programme to support of radical hysterectomy is described over 4 years (1991–95), during which 48 patients participated in the autologous blood programme, and 63 did not to do so. All but one of the autologous donors received autologous blood but only two received allogeneic blood. Forty‐three of the autologous nondonors received no transfusion and 20 received allogeneic blood. These differences are highly significant.

For the 48 autologous donors, 91% of the blood requested was collected, and of that 91% was used, for a ‘wastage’ rate of 9%. The mean blood use was significantly greater in the autologous donors. Blood loss was not significantly different between the two groups.

The data confirm the validity of the autologous blood order schedule of 2 units for radical hysterectomy.
A pharmacokinetic/pharmacodynamic model for the action of anti‐D immunoglobulin in effecting circulatory clearance of Rh D+ red cells
Authors: Chapman G. E.
Published: April 2008

Summary. A dynamic model of the action of anti‐D immunoglobulin in effecting clearance of Rh D‐positive red cells from the circulation of D‐negative subjects is presented. The pharmacokinetics of the redistribution of anti‐D between injection site, intravascular and extravascular spaces following either intramuscular or intravenous administration is included, also the reaction of anti‐D with D‐positive red cells in the intravascular space and subsequent circulatory clearance of antibody‐coated cells. Numerical computer modelling methods have been used to obtain solutions of the model, using kinetic rate constants which have been derived from previously published experimental data. Selected solutions are presented, chosen for their relevance to (i) clinical situations in which anti‐D is used to prevent Rh D immunization of D‐negative subjects and (ii) determination of some of the properties of anti‐D antibodies which are important for effecting circulatory clearance of D‐positive red cells.
Use of prostaglandin E1 during preparation of platelet concentrates
Authors: Hawker R. J. , Turner V. S. , Mitchell S. G.
Published: April 2008

Summary. A paired study in 10 autologous volunteer donors was undertaken to investigate the efficacy of adding prostaglandin E1 (PGE1) in vitro during routine platelet concentrate (PC) production. After 5 days storage, PCs prepared with PGE1 were compared with control PCs. In vivo platelet recovery, survival and biodistribution were determined following autologous infusion of indium‐111 labelled platelets into volunteers, together with the in vitro evaluation of platelet function and biochemistry.

PGE1 facilitated easier and faster platelet resuspension following centrifugation. After storage there were few significant in vitro differences between PCs prepared with PGE1 and control PCs. The artifactual leucocyte concentration was significantly lower in the presence of PGE1, suggesting less platelet aggregates had been formed during storage and β‐thromboglobulin release was significantly reduced by PGE1, 14.0±6.0 μg per 109platelets compared with 22.3±9.8μg per 109platelets in control PCs, (P < 0.01), indicating PGE1 reduced both platelet aggregation and activation probably at the initial preparation stage, known to produce the greatest trauma.

Initial in vivo platelet recovery for PCs prepared with PGE1 was similar to that of control PCs, 41.1 ± 12.5% vs. 44.4±80%, respectively, and there were no differences in organ distribution at 24h. However, in vivo multiple hit survival was reduced in the presence of PGE1, 5.8 ± 1.6 days compared with 6.9 ± 1.4 days in control PCs (P < 0.05).

Despite the ability of PGE1 to facilitate platelet resuspension and inhibit platelet aggregation and activation during preparation of the PCs, the reduced in vivo survival time may preclude the use of PGE1 during routine PC preparation.
The IgA‐deficient blood donor: something in the air?
Authors: Munks R.
Published: April 2008

Summary. In May 1994, the Blood Transfusion Centre, Sheffield, introduced a new screening test for Immunoglobulin A (IgA) deficiency. The test is performed in parallel with routine donor ABO grouping and Rh typing on two Olympus PK 7200 autoanalysers. A panel of IgA‐deficient donors is required to provide blood products for IgA‐deficient patients in whom the presence of anti‐IgA antibodies may cause serious anaphylactic transfusion reactions (Welborn & Hersch, 1991). Detection rates during high summer became noticeably inconsistent and since a relationship between IgA deficiency and hypersensitivity states is recognized (Amman & Hong, 1971), a comparison between the detection rate and pollen levels during June and July 1994 was undertaken; the results of this study are presented here.
Dried sera for confirming blood‐borne virus infections (HCV, HTLV‐I, HIV & HBsAg)*
Authors: Das P. C. , de Vries A. H. , McShine R. L. , Sibinga C. Th. Smit
Published: April 2008

Summary. For safe blood transfusion, developing countries face considerable problems including serological screening and confirmation of blood‐borne virus infections (HCV, HTLV‐I, HIV and HBsAg). Confirmation tests are not only costly but also require sophisticated techniques and expertise. In order to provide this support we have attempted to perform a virus antibody confirmation test on samples dried on blotting paper (BP). Forty‐nine sera derived from selected patients and donors from Bombay, and nine donors' sera from Bellarussia were transported on BP. In control experiments, dilutions of antibody‐positive sera (HIV, HTLV‐I & HCV) and ‘blinded’ HTLV‐I antibody‐positive and antibody‐negative donors were applied on BP. Eluates from snipped BP were tested initially by screening tests, and the reactives were subjected to confirmatory tests for three types of virus antibody tests (HCV, HTLV‐I & HIV) by blotting methods and neutralisation tests for HBsAg. There was considerable reduction of titres in dry sera but all BP‐derived dry specimens gave excellent qualitative concordance with their liquid‐equivalent sera, and the HTLV‐I‐positive donor was identified and reconfirmed correctly. Presence of only HCV antibody was confirmed in all the nine selected Bellarussian donors. Blood donors in Bombay had 3% HIV antibody, 6% HBsAg and none had HCV antibody, while selected patients showed substantially higher levels of these markers: HIV‐antibody 64%, HBsAg 57% and HCV‐antibody 17% confirmed positive. The cause of this high level remains to be established. Dry samples received by post seem to be an economical approach to a first step in providing some levels of independent confirmation of reactives in developing countries.
Differences in post‐operative infection rates between patients receiving autologous and allogeneic blood transfusion: a meta‐analysis of published randomized and nonrandomized studies
Authors: Duffy G. , Neal K. R.
Published: April 2008

Summary. We have undertaken a meta‐analysis of the post‐operative infection rates in patients who received autologous blood compared with allogeneic blood. Nine studies published after 1989 were identified, of which seven had sufficient data on transfusion given in the paper to be included, giving a total of 1060 patients. The risk of post‐operative infection was greater in the allogeneic group, odds ratio 2.37 (95% confidence interval (CI) 1.6‐3.6, P < 0.0001) compared with the autologous group. Allogeneic and autologous blood transfusion should be compared in a large multicentre randomized control trial.
Lymphocyte phenotypes and infection incidence in transfused preterm neonates1
Authors: Kutvirt S. G. , Armon M. E. , Simon T. L. , Lewis S. L.
Published: April 2008

SUMMARY. The immunomodulating effects of repeated exposure to blood from multiple donors coupled with an immature immune system may predispose the preterm neonate to an increased incidence of infection in his first few months of life. To test this hypothesis, we compared lymphocyte phenotypes, serum IgG concentrations, and histories of infection and rehospitalization in neonates at 4 months corrected age. Two of the study groups were preterm infants who had been transfused with either frozen, deglycerolized or CMV‐negative, γ‐irradiated blood. Control groups consisted of nontransfused term and preterm infants. There were no differences found in lymphocyte phenotypes or serum IgG concentrations of controls or transfused infants. No differences were found in the infection or rehospitalization incidence in the transfused infants as compared with nontransfused preterm neonates. We failed to show differences in immune parameters or in infection and rehospitalization rates of the preterm infants analysed. Alongside previously published reports, our data suggest that red cell transfusions have a minimal impact on the immature immune system of the neonate.
CNS lymphomatoid granulomatosis with lymph node and bone marrow involvements
Authors: Takiyama Akihiro , Nishihara Hiroshi , Tateishi Ukihide , Kimura Taichi , Lei Wang , Marukawa Katsuji , Itoh Tomoo , Hashino Satoshi , Nagashima Kazuo , Tanaka Shinya
Published: April 2008

Lymphomatoid granulomatosis (LYG) in the CNS is an uncommon lymphoproliferative disease with characteristic angiocentric lymphoreticular proliferative and granulomatous lesions exhibiting low‐grade malignant potential. Here we report a rare case of CNS‐LYG, which disseminated to the lymph node and bone marrow. A 50‐year‐old man was diagnosed with CNS‐LYG based on brain biopsy showing perivascular infiltration of CD3‐positive small T‐lymphocytes without overt nuclear atypism. Eight months after the initial neurological symptoms, inguinal lymph node swelling was found and histopathologically diagnosed as peripheral T‐cell lymphoma. TCRγ‐gene rearrangement study using both paraffin‐embedded specimens of brain and inguinal lymph node demonstrated an identical clonal band. Considering the clinical course, we concluded lymph node involvement of CNS‐LYG, suggesting the malignant potential of CNS‐LYG.
The activation of ERK1/2 MAP kinases in glioblastoma pathobiology and its relationship with EGFRamplification
Authors: Lopez‐Gines Concha , Gil‐Benso Rosario , Benito Rafa , Mata Manolo , Pereda Javier , Sastre Juan , Roldan Pedro , Gonzalez‐Darder Jose , Cerdá‐Nicolás Miguel
Published: April 2008

The ERK1/2 activated protein kinase (MAPK) pathway is a critical signaling system that mediates ligand‐stimulated signals for the induction of cell proliferation, differentiation and survival, involved in malignant transformation. The purpose of this study was to determine the activation of ERK1/2 in this tumor, and to determine the relationship of ERK1/2 activation with the amplification/overexpression of EGFR as well as with 9p21 locus gene alterations, both of which are genetic factors frequently associated with glioblastoma. We used immunohistochemistry and Western blot analysis to analyze the activation of ERK1/2 in 22 patients with glioblastoma, and we studied the amplification/overexpression of EGFR; as well as the molecular alterations in 9p21 locus genes. Positive immunostaining ERK1/2 was observed in 86.4% of the tumors, displaying mainly nuclear immunolocalization; and by immunoblotting, ERK1/2 was activated in 68% of the cases. The 70% of cases with EGFR amplification presented activated ERK1/2. The joint presence of amplified EGFR and alterations in the 9p21 genes was observed in 50% of the cases, whereas the simultaneous occurrence of these two phenomena with the activation of ERK1/2 was observed in 40% of the cases. Our results suggest that the activation of ERK1/2 is implicated in the pathobiology of glioblastoma. This activation of ERK1/2 is probably related in part to the amplification of EGFR as well as to alterations in 9p21 locus genes (homozygous deletion and promoter methylation). However, the activation of ERK1/2 also involves pathways that are independent of the EGFR.
Unstable CA1 place cell representation in rats with entorhinal cortex lesions
Authors: Van Cauter Tiffany , Poucet Bruno , Save Etienne
Published: April 2008

Recent studies emphasize the importance of the entorhinal cortex in spatial representation and navigation. Furthermore, evidence is accumulating to show that spatial processing depends on interactions between the entorhinal cortex and the hippocampus. To investigate these interactions, we examined the effects of entorhinal cortex lesions on the activity of hippocampal CA1 place cells. Rats received bilateral radiofrequency lesions of the entorhinal cortex or sham lesions before place cell recording. Place cells were recorded as the rats performed a pellet‐chasing task in a cylinder containing three cue‐objects. Entorhinal cortex lesions did not abolish place cell spatial firing but reduced noticeably discharge rate and field size. Most importantly, the lesions affected firing field stability when cells were recorded both in constant conditions and following cue manipulations (object rotation, object removal). These findings indicate that the entorhinal cortex is necessary for the stability of hippocampal representations across exposures to a familiar environment. Consistent with the recent discovery of grid cells in the medial entorhinal cortex, our results suggest that the entorhinal cortex contributes to providing a spatial framework that would enable the hippocampus to maintain stable environment‐specific representations.
Stress‐induced analgesia in mice: evidence for interaction between endocannabinoids and cholecystokinin
Authors: Kurrikoff Kaido , Inno Jan , Matsui Toshimitsu , Vasar Eero
Published: April 2008

Stress‐induced analgesia (SIA) is an important endogenous mechanism in response to stressful stimuli. Opioid peptides, as well as endocannabinoids, are known mediators of SIA. We were interested in whether the endocannabinoid tone and the resulting SIA could be influenced by changing the activity of cholecystokinin (CCK) in mice. This hypothesis is related to recent evidence showing a cellular colocalization of neuropeptide CCK and cannabinoid type 1 (CB1) receptors in many central nervous system structures. However, the physiological relevance of this colocalization is unknown. Our aim was to test whether abolishing the endogenous CCK tone might influence the cannabinoid‐mediated form of SIA. As expected, the CB1 antagonist rimonabant prevented the development of analgesia in response to footshock‐induced stress in wild‐type mice. In contrast, CCK type 2 (CCK2) receptor‐deficient mice developed SIA regardless of rimonabant treatment. Naloxone, an opioid antagonist, antagonized SIA in both wild‐type and CCK2 receptor‐deficient homozygous mice. This finding suggests that CCK, through CCK2 receptors, modulates the action of endocannabinoids. Gene expression analysis revealed an up‐regulation of CCK2 receptor gene in the lumbar spinal cord and mesolimbic area in wild‐type mice in response to stress. In addition, wild‐type mice displayed up‐regulation of genes implicated in endocannabinoid‐mediated neurotransmission (elevation of CB1 receptor, 2‐arachidonoylglycerol and the anandamide‐synthesizing enzymes sn‐1‐diacylglycerol lipase alpha and N‐acyl‐phosphatidylethanolamine‐hydrolysing phospholipase D) in response to stress in the lumbar spinal cord and mesolimbic area. We did not find any of these changes in CCK2 receptor‐deficient homozygous mice. Altogether, behavioural and gene expression studies reflect an involvement of CCK2 receptors in the development of endocannabinoid‐mediated SIA.
A circulating ghrelin mimetic attenuates light‐induced phase delay of mice and light‐induced Fos expression in the suprachiasmatic nucleus of rats
Authors: Yi Chun‐Xia , Challet Etienne , Pévet Paul , Kalsbeek Andries , Escobar Carolina , Buijs Ruud M.
Published: April 2008

Anatomical evidence suggests that the ventromedial arcuate nucleus (vmARC) is a route for circulating hormonal communications to the suprachiasmatic nucleus (SCN). Whether this vmARC–SCN connection is involved in the modulation of circadian activity of the SCN is not yet known. We recently demonstrated, in rats, that intravenous (i.v.) injection of a ghrelin mimetic, GHRP‐6, during the daytime activated neurons in the vmARC and reduced the normal endogenous daytime Fos expression in the SCN. In the present study we show that i.v. administration of GHRP‐6 decreases light‐induced Fos expression at ZT13 in the rat SCN by 50%, indicating that light‐induced changes in the SCN Fos expression can also be reduced by GHRP‐6. Because it is difficult to study light‐induced phase changes in rats, we examined the functional effects of GHRP‐6 on light‐induced phase shifts in mice and demonstrated that peripherally injected GHRP‐6 attenuates light‐induced phase delays at ZT13 by 45%. However, light‐induced Fos expression in the mice SCN was not blocked by GHRP‐6. These results illustrate that acute stimulation of the ghrelinergic system may modulate SCN activity, but that its effect on light‐induced phase shifts and Fos expression in the SCN might be species related.
Diversity, function and evolution of genes coding for putative Ni‐containing superoxide dismutases
Authors: Dupont C. L. , Neupane K. , Shearer J. , Palenik B.
Published: April 2008

We examined the phylogenetic distribution, functionality and evolution of the sodN gene family, which has been shown to code for a unique Ni‐containing isoform of superoxide dismutase (Ni‐SOD) in Streptomyces. Many of the putative sodN sequences retrieved from public domain genomic and metagenomic databases are quite divergent from structurally and functionally characterized Ni‐SOD. Structural bioinformatics studies verified that the divergent members of the sodN protein family code for similar three‐dimensional structures and identified evolutionarily conserved amino acid residues. Structural and biochemical studies of the N‐terminus ‘Ni‐hook’ motif coded for by the putative sodN sequences confirmed both Ni (II) ligating and superoxide dismutase activity. Both environmental and organismal genomes expanded the previously noted phylogenetic distribution of sodN, and the sequences form four well‐separated clusters, with multiple subclusters. The phylogenetic distribution of sodN suggests that the gene has been acquired via horizontal gene transfer by numerous organisms of diverse phylogenetic background, including both Eukaryotes and Prokaryotes. The presence of sodN correlates with the genomic absence of the gene coding for Fe‐SOD, a structurally and evolutionarily distinct isoform of SOD. Given the low levels of Fe found in the marine environment from where many sequences were attained, we suggest that the replacement of Fe‐SOD with Ni‐SOD may be an evolutionary adaptation to reduce iron requirements.
Changes in species richness of vascular plants under the impact of air pollution: a global perspective
Authors: Zvereva Elena L. , Toivonen Eija , Kozlov Mikhail V.
Published: April 2008

Aim To investigate the general pattern of changes in species richness and diversity of vascular plants due to environmental contamination and associated habitat changes imposed by point polluters, and identify the sources of variation in the response of plant communities to industrial pollution.

Location Global.

Methods We collected species richness and diversity data from 86 studies that were conducted around 60 atmospheric point polluters worldwide and reported in 95 papers (published in 1953–2007). We used meta‐analysis to search for a general effect and to compare between polluter types and plant groups, and linear regression to describe the latitudinal gradient and to quantify relationships between pollution and effect size.

Results Although the species richness of vascular plants generally decreased with pollution, the effects were not uniform across the studies. Polluters that cause soil acidification imposed a stronger detrimental effect on plant diversity than industries whose emissions increased soil pH. An overall adverse effect was primarily due to the contribution of non‐ferrous smelters and aluminium plants; the effects of other SO2‐emitting industries were less detrimental, albeit negative, and the effects of chemical plants, fertilizer factories and cement industries did not differ from zero. Longevity of the pollution impact only made a slight contribution to the detected variation, while adverse effects increased with increase in pollution load.

Main conclusions This study is the first demonstration of geographical variation in the responses of plant communities to aerial emissions: adverse effects increased from high to low latitudes, and this pattern was explained primarily by increases in both the diversity of original (undisturbed) communities and mean summer temperatures. The latter result suggests that under a future warmer climate the existing pollution loads may become more harmful. Model calculations indicate that a detectable depauperation of plant communities is unlikely if the polluter emits < 1500 t of SO2annually.
Why does the unimodal species richness–productivity relationship not apply to woody species: a lack of clonality or a legacy of tropical evolutionary history?
Authors: Laanisto Lauri , Urbas Pille , Pärtel Meelis
Published: April 2008

Aim  To study how differences in species richness patterns of woody and herbaceous plants may be influenced by ecological and evolutionary factors. Unimodal species richness–productivity relationships (SRPRs) have been of interest to ecologists since they were first described three decades ago for British herbaceous vegetation by J. P. Grime. The decrease in richness at high productivity may be due to competitive exclusion of subordinate species, or diverse factors related to evolution and dispersal. Unimodal SRPRs are most often reported for plants, but there are exceptions. For example, unimodal SRPRs are common in the temperate zone but not in the tropics. Similarly, woody species and forest communities in the Northern Hemisphere do not tend to show unimodal SRPRs.

Location  Global.

Methods  We used data from the literature to test whether a unimodal SRPR applies to woody species and forest communities on a global scale. We explored whether the shape of SRPRs may be related to the lack of clonality in woody species (which may prevent their being competitively superior), or the legacy of evolutionary history (most temperate woody species originate from tropical lineages, and due to niche conservatism they may still demonstrate ‘tropical patterns’). We used case studies that reported the names of the dominant or most abundant species for productive sites.

Results  Woody species were indeed less clonal than herbaceous species. Both clonality and the temperate evolutionary background of dominating species were associated with unimodality in SRPRs, with woodiness modifying the clonality effect.

Main conclusions  The unimodal SRPR has been common in the ecological literature because most such studies originate from temperate herbaceous communities with many clonal species. Consequently, both evolutionary and ecological factors may influence species richness patterns.
The maintenance of a positive spatial correlation between South African bird species richness and human population density
Authors: Hugo Sanet , Van Rensburg Berndt J.
Published: April 2008

Aim  To investigate explanations for the maintenance of a positive spatial species richness–human population density correlation at broad scales, despite the negative impact of humans on species richness. These are (hypotheses 1–4): (1) human activities that create a habitat mosaic and (2) a more favourable climate, and (3) adequate conservation measures (e.g. sufficient natural habitat), maintain the positive species richness–human density correlation; or (4) the full range of human densities decrease the slope of the correlation without changing its form.

Location  South Africa.

Methods  Avian species richness data from atlas distribution maps and human population density data derived from 2001 census results were converted to a quarter‐degree resolution. We investigated the number of land transformation types (anthropogenic habitat heterogeneity), irrigated area (increasing productivity), and other covarying factors (e.g. primary productivity) as predictors of species richness. We compared species richness–human density relationships among regions with different amounts of natural habitat, and investigated whether the full range of human densities decrease species richness in relation to primary productivity.

Results  Hypotheses 1, 2 and 3 were supported. Human densities and activities that increase habitat heterogeneity and productivity are important beneficial factors to common species, but not to rare species. The species richness–human density relationship persists only at low land transformation levels, and no significant relationship exists at higher levels. For common species, the relationship becomes non‐significant at lower land transformation levels than for rare species.

Main conclusions  The persistence of the species richness–human density relationship depends mostly on the amount of remaining natural habitat. In addition, certain human activities benefit especially common species. Common species seem to be more flexible than rare species in response to human activity and habitat loss.
Model selection and information theory in geographical ecology
Authors: Diniz‐Filho José Alexandre Felizola , Rangel Thiago Fernando L. V. B. , Bini Luis Mauricio
Published: April 2008

Aim Although parameter estimates are not as affected by spatial autocorrelation as Type I errors, the change from classical null hypothesis significance testing to model selection under an information theoretic approach does not completely avoid problems caused by spatial autocorrelation. Here we briefly review the model selection approach based on the Akaike information criterion (AIC) and present a new routine for Spatial Analysis in Macroecology (SAM) software that helps establishing minimum adequate models in the presence of spatial autocorrelation.

Innovation  We illustrate how a model selection approach based on the AIC can be used in geographical data by modelling patterns of mammal species in South America represented in a grid system (n = 383) with 2° of resolution, as a function of five environmental explanatory variables, performing an exhaustive search of minimum adequate models considering three regression methods: non‐spatial ordinary least squares (OLS), spatial eigenvector mapping and the autoregressive (lagged‐response) model. The models selected by spatial methods included a smaller number of explanatory variables than the one selected by OLS, and minimum adequate models contain different explanatory variables, although model averaging revealed a similar rank of explanatory variables.

Main conclusions  We stress that the AIC is sensitive to the presence of spatial autocorrelation, generating unstable and overfitted minimum adequate models to describe macroecological data based on non‐spatial OLS regression. Alternative regression techniques provided different minimum adequate models and have different uncertainty levels. Despite this, the averaged model based on Akaike weights generates consistent and robust results across different methods and may be the best approach for understanding of macroecological patterns.
Incentives to Reduce Crop Trait Durability
Authors: Ambec Stefan , Langinier Corinne , Lemarié Stéphane
Published: April 2008

To reduce the competition from farmers who self‐produce seed, an inbred line seed producer can switch to nondurable hybrid seed. In a two‐period framework, we first investigate the impact of crop durability on self‐production, pricing and switching decisions. Second, we study how the introduction of a fee paid by self‐producing farmers affects those decisions. We find that the monopolist may produce technologically dominated hybrid seed in order to extract more surplus from farmers. Further, the introduction of a self‐production fee improves efficiency.
Differentiation and Synergies in Rural Tourism: Estimation and Simulation of the Israeli Market
Authors: Tchetchik Anat , Fleischer Aliza , Finkelshtain Israel
Published: April 2008

This article applies a discrete‐choice equilibrium model with product differentiation to study the rural tourism industry in Israel and to jointly estimate the effect of lodging and farm characteristics on consumer preferences and firms' costs. The model accounts for heterogeneity in tastes and technologies and allows for unobservable product characteristics. We find evidence for technological synergy in the joint production of agricultural goods and rural tourism services, but none in the demand. The differentiation in the industry is the major contributor to the price‐cost margin, which averages 62%. An additional minor cause is government regulations, which restrict supply. Simulation results demonstrate the growth potential of the industry and show that the government can play an important role in catalyzing growth via investment subsidization, deregulation of supply and information distribution.
Risk Rationing and Wealth Effects in Credit Markets: Theory and Implications for Agricultural Development
Authors: Boucher Stephen R. , Carter Michael R. , Guirkinger Catherine
Published: April 2008

We develop a model that shows that asymmetric information can result in two types of credit rationing: conventional quantity rationing, and “risk rationing,” whereby farmers are able to borrow but only under high‐collateral contracts that offer them lower expected well‐being than a safe, subsistence activity. After exploring its incidence with respect to wealth, we show that risk rationing has important policy implications. Specifically, land titling will be only partially effective because it does not enhance producers' willingness to offer up the collateral needed to secure loans under moral hazard constraints. Efforts to enhance agricultural investment and the working of agricultural credit markets must step beyond land titling and also deal with risk.
A Cost Approach to Economic Analysis Under State‐Contingent Production Uncertainty
Authors: Chavas Jean-Paul
Published: April 2008

This article explores the economics of input decision under production uncertainty. The article develops a methodology to specify and estimate cost‐minimizing input decisions under a state‐contingent technology. The analysis is applied to time series data on U.S. agriculture. It finds strong empirical evidence that expected output alone does not provide an appropriate representation of production uncertainty. The results provide empirical support for an output‐cubical technology. This indicates that anex postanalysis of stochastic technology appears appropriate. The analysis also provides evidence that the cost of facing production risk has declined in U.S. agriculture over the last few decades.
Avocado Pests and Avocado Trade
Authors: Peterson Everett B. , Orden David
Published: April 2008

This article evaluates the effects of a November 2004 phytosanitary rule that removed seasonal and geographic restrictions on the importation of fresh Hass avocados from approved orchards in Mexico to the United States. With the remaining systems approach compliance measures in place, pest risks do not substantially increase and U.S. net welfare rises by $77 million. Removal of remaining compliance measures may lead to lower net welfare gains depending on which measures are eliminated and the estimated probabilities of pest infestations.
Proportion of Non-Zero Normal Means: Universal Oracle Equivalences and Uniformly Consistent Estimators
Authors: Jin Jiashun
Published: April 2008

Since James and Stein's seminal work, the problem of estimating n normal means has received plenty of enthusiasm in the statistics community. Recently, driven by the fast expansion of the field of large-scale multiple testing, there has been a resurgence of research interest in the n normal means problem. The new interest, however, is more or less concentrated on testing n normal means: to determine simultaneously which means are 0 and which are not. In this setting, the proportion of the non-zero means plays a key role. Motivated by examples in genomics and astronomy, we are particularly interested in estimating the proportion of non-zero means, i.e. given n independent normal random variables with individual means Xj∼N(μj,1), j=1,…,n, to estimate the proportion ɛn=(1/n) #{j:μj /= 0}. We propose a general approach to construct the universal oracle equivalence of the proportion. The construction is based on the underlying characteristic function. The oracle equivalence reduces the problem of estimating the proportion to the problem of estimating the oracle, which is relatively easier to handle. In fact, the oracle equivalence naturally yields a family of estimators for the proportion, which are consistent under mild conditions, uniformly across a wide class of parameters. The approach compares favourably with recent works by Meinshausen and Rice, and Genovese and Wasserman. In particular, the consistency is proved for an unprecedentedly broad class of situations; the class is almost the largest that can be hoped for without further constraints on the model. We also discuss various extensions of the approach, report results on simulation experiments and make connections between the approach and several recent procedures in large-scale multiple testing, including the false discovery rate approach and the local false discovery rate approach.
A Semiparametric Approach to Canonical Analysis
Authors: Xia Yingcun
Published: April 2008

Classical canonical correlation analysis is one of the fundamental tools in statistics to investigate the linear association between two sets of variables. We propose a method, called semiparametric canonical analysis, to generalize canonical correlation analysis to incorporate the important non-linear association. Semiparametric canonical analysis is easy to implement and interpret. Statistical properties are proved. A consistent estimation method is developed. Selection of significant semiparametric canonical analysis components is discussed. Simulations suggest that the methods proposed have satisfactory performance in finite samples. One environmental data set and one data set in social science are investigated, in which non-linear canonical associations are observed and interpreted.
A Wavelet- or Lifting-Scheme-Based Imputation Method
Authors: Heaton T. J. , Silverman B. W.
Published: April 2008

The paper proposes a new approach to imputation using the expected sparse representation of a surface in a wavelet or lifting scheme basis. Our method incorporates a Bayesian mixture prior for these wavelet coefficients into a Gibbs sampler to generate a complete posterior distribution for the variable of interest. Intuitively, the estimator operates by borrowing strength from those observed neighbouring values to impute at the unobserved sites. We demonstrate the strong performance of our estimator in both one- and two-dimensional imputation problems where we also compare its application with the standard imputation techniques of kriging and thin plate splines.
On Casting Random-Effects Models in a Survival Framework
Authors: Pilla Ramani S. , Kim Yongdai , Lee Hakbae
Published: April 2008

Logistic random-effects models are often employed in the analysis of correlated binary data. However, fitting these models is challenging, since the marginal distribution of the response variables is analytically intractable. Often, the random effects are treated as missing data for constructing traditional data augmentation algorithms. We create a novel alternative data augmentation scheme that simplifies the likelihood-based inference for logistic random-effects models. We cast the random-effects model in a ‘survival framework’, where each binary response is the censoring indicator for a survival time that is treated as additional missing data. Under this augmentation framework, the conditional expectations are free of unknown regression parameters. Such a construction has a particular advantage that, in the case of discrete covariates, the score equations for regression parameters have analytical solutions. Consequently, one does not need to resort to a search algorithm in estimating the regression parameters. We further create a parameter expansion scheme for logistic random-effects models under this survival data augmentation framework. The proposed data augmentation is illustrated when the random-effects distribution follows a multivariate Gaussian and multivariate t-distribution. The performance of the method is assessed through simulation studies and a real data analysis.
Teacher‐ and Learner‐Led Discourse in Task‐Based Grammar Instruction: Providing Procedural Assistance for L2 Morphosyntactic Development
Authors: Toth Paul D.
Published: April 2008

This study compares quantitative and qualitative results for task‐based second language (L2) grammar instruction conducted as whole‐class, teacher‐led discourse (TLD) versus small‐group, learner‐led discourse (LLD). Participants included 78 English‐speaking adults from six university classes of beginning L2 Spanish, with two assigned to each treatment (LLD = 25; TLD = 28) and two others comprising a control group (n= 25). Instruction involved seven lessons targeting the anticausative cliticse, with one recorded and transcribed in each treatment. Results on grammaticality judgment and guided production tasks administered as a pretest, posttest, and delayed posttest indicated a stronger performance for TLD learners on both tasks. The transcript data suggest a potential for teachers to facilitate L2 learning by directing attention to target structures and providing procedural assistance for processing output.
Deaf Learners' Knowledge of English Universal Quantifiers
Authors: Berent Gerald P. , Kelly Ronald R. , Porter Jeffrey E. , Fonzi Judith
Published: April 2008

Deaf and hearing students' knowledge of English sentences containing universal quantifiers was compared through their performance on a 50‐item, multiple‐picture task that required students to decide whether each of five pictures represented a possible meaning of a target sentence. The task assessed fundamental knowledge of quantifier sentences, recognition of quantifier sentence ambiguity, and preferences for specific sentence interpretations. Results revealed that deaf learners at middle school, high school, and college levels of education understand the fundamental meaning of universal quantifier sentences but differ in certain aspects from hearing native speakers in their preferred interpretations. Differences between deaf and hearing learners are explained in terms of economy principles associated with minimalism and aspects of semantic complexity. The findings contribute to our understanding of language acquisition under conditions of restricted access to spoken language input as well as to language acquisition generally.
DOES ORGANIZATION MATTER? A STUDY OF PHYSICIANS' IDEAL ORGANIZATION
Authors: Brorström Björn , Nilsson Viveka
Published: April 2008

It is a known phenomenon that it is difficult to make organizational changes within professional organizations. One recurring observation and experience from health care studies is that it is difficult to discuss the last organizational change with professionals because the most recent change is always perceived as the worst. In order to avoid this routine response, the authors of this article asked 56 senior physicians from the Swedish health care sector what their ideal organization looks like. The authors note that there is a strong institutionalized idea among the physicians of how health care should be organized. The image is not particularly complicated: the organization should be based on the meeting between doctor and patient. One conclusion in the article is that professionals dislike change, but nevertheless, they still want it. Actual change is not the problem – only changes that are not in compliance with the professionals' opinions of organization and management.
Thick melanoma: the problem continues
Authors: Tejera‐Vaquerizo A , Mendiola‐Fernández M , Fernández‐Orland A , Herrera‐Ceballos E
Published: April 2008

Background  The incidence of melanoma and its associated mortality has stabilized over the recent years, due in part to efforts directed at better prevention and detection of these lesions. We analysed the trends in the distribution of melanomas, mainly according to their thickness.

Methods  Data from the Dermatology Service of ‘Virgen de la Victoria’ University Hospital in Malaga (Spain) showed a total of 459 cases of melanoma between 1990 and 2005, both inclusive. The lesions were stratified according to year of diagnosis (1990–96 and 1997–2005), sex, age (0–49, ≥ 50), thickness (0–0.99, 1.00–1.99, and ≥ 2 mm) and the histological subtype [lentigo maligna melanoma (LMM), superficial spreading melanoma (SSM), nodular melanoma (NM) and acral lentiginous melanoma (ALM)]. Particular attention was given to the distribution of the groups according to thickness.

Results  The number of new cases rose by 92% between the two study periods (1990–1996 and 1997–2005). However, the number of new cases of thick melanoma remained almost constant over the two periods, being associated with persons over 50 years of age (65.1% vs. 64.3%), with men having half the cases (48.4% vs. 47%). The proportion of nodular melanomas within the group of thick melanomas was high in both periods (36.5% and 39.3%, respectively).

Conclusions  This study shows that despite the large increase in new melanomas, the diagnosis of thick melanomas has remained constant, mainly in persons over the age 50 years, with a relative increase in men. New strategies and education programmes are, therefore, required for the early detection of this type of tumour to reduce its incidence in these patients.
The efficacy of topical 0.2% hyaluronic acid gel on recurrent oral ulcers: comparison between recurrent aphthous ulcers and the oral ulcers of Behçet's disease
Authors: Lee JH , Jung JY , Bang D
Published: April 2008

Background  Hyaluronic acid (HA) is a primary component of the extracellular matrix, and the efficacy of HA on oral ulcers is rarely reported.

Objective  To observe the efficacy and safety of the topical application of 0.2% HA gel on recurrent oral ulcers and to compare its effects in patients with recurrent aphthous ulcers (RAU) and the oral ulcers of Behçet's disease (BD)

Materials and methods  Thirty‐three outpatients with recurrent oral ulcers were included in the study (17 patients: BD, 16 patients: RAU). The patients used topical 0.2% HA gel twice daily for 2 weeks. The subjective parameters of patients [number of ulcers, healing period, visual analogue scale (VAS) for pain] were investigated and objective assessments (number of ulcers, maximal area of ulcer and inflammatory signs) were inspected by a physician.

Results  A subjective reduction in the number of ulcers was observed in 72.7% of the patients. A decrease in the ulcer healing period was observed in 72.7% of the patients; 75.8% experienced improvement in VAS for pain. Objective inspection of the ulcers showed a reduction of numbers in 57.6% of the patients, and 78.8% of the ulcers showed a decrease in area. Among the inflammatory signs, swelling and local heat were significantly improved after treatment. No significant differences were found between the BD group and RAU group in subjective and objective parameters, except for inflammatory signs. No side‐effects were observed.

Conclusions  The topical application of 0.2% HA gel seems to be an effective and safe therapy in patients with recurrent oral ulcers; the study supports the use of HA in BD with oral ulcers.
Is there an easier way to autograft skin in chronic leg ulcers? ‘Minced micrografts’, a new technique
Authors: Boggio P , Tiberio R , Gattoni M , Colombo E , Leigheb G
Published: April 2008

Background  Chronic venous leg ulcers represent an urgent and increasing problem for public health. The use of skin autografts results in a greater therapeutic success in healing chronic ulcers.

Objective  A simple method of skin autografting that could permit a wider use of skin grafts in outpatients is needed. A new technique allowing skin autografting in a simple one‐step process, without complex surgical procedures or expensive technical supplies, is presented.

Methods  A small, full‐thickness skin specimen taken from the patient is finely minced and spread on his leg ulcer bed allowing to cover a surface many times wider than the sample itself.

Results  This method induces faster re‐epithelization of chronic leg ulcers that failed to heal despite good conservative local therapy and give the possibility to repair very large ulcers with small fragments of skin. A clinical case is shown as an example out of 20 ulcers we recently treated.

Conclusion  Our preliminary report shows that this technique results in a greater therapeutic success (18 of 20 cases) in healing chronic leg ulcers, a common pathology that often affects outpatients treated for very long periods at home or in the Dermatologist's office. In our experience, this new and successful reparative possibility makes ‘mince grafting’ a recommendable procedure.
The application of structured‐light illumination microscopy to hydrocarbon‐bearing fluid inclusions
Authors: BLAMEY N. J. F. , RYDER A. G. , FEELY M. , DOCKERY P. , OWENS P.
Published: April 2008

Structured‐light illumination (SLI)‐based microscopy offers geologists a new perspective for screening of hydrocarbon‐bearing (HCFI) and small aqueous fluid inclusion (AFI) assemblages. This optical‐sectioning technique provides rapid, confocal‐like imaging, using relatively simple and inexpensive instrumentation. The 3D fluorescent images of HCFI planes and large single HCFIs permit the visualization of the relationships between HCFI assemblages, examination of HCFI morphology, and volume estimates of the fluorescent components within HCFIs. By the use of normal white light illumination, SLI image capture, and varying acquisition time it is also possible to image AFI because of the random movements of vapour bubbles within the inclusions. This allows the near‐simultaneous visualization of hydrocarbon and AFI which is of significant importance for the study of sedimentary basins and petroleum reservoirs. SLI is a unique and accessible 3D petrographic tool, with practical advantages over conventional epifluorescence and confocal laser scanning microscopy.