bluuebunny/crossref_metadata_2025 huggingface dataset:
Mammalian repetitive DNA sequences in a stable Robertsonian system
Authors: Kurnit D.M. , Brown F.L. , Maio J.J.
Published: May 2008

The calf, sheep, and goat are members of a stable Robertsonian system, the superfamily Bovoidea, in which karyotypic evolution occurs almost exclusively by centric rearrangements. The centromeric DNA sequences in this system have been studied by buoyant density analysis and by intraspecies and interspecies in situ cytological hybridization. The results obtained with four satellite DNAs (I-IV) of the calf, satellites I and II of the sheep, and satellites I and II of the goat are as follows: 1. Satellite I of the sheep and satellite I of the goat are nearly identical by buoyant density analysis in CsCl at pH 8.4 and pH 12.5, but they differ from satellite I of the calf. Satellite II of the sheep and satellite II of the goat differ from each other and from calf satellite II in their physical properties. 2. Centromerically located satellites I and III of the calf show no homology with centromeric sequences of the sheep or goat chromosomes by in situ hybridization. Sequences homologous to calf satellite IV show limited homology to similar sequences in sheep and goat chromosomes. 3. Sheep and goat satellites I and II show no homology to centromeric DNA sequences in the calf chromosomes. 4. Sequences complementary to sheep satellites I and II hybridize efficiently to centromeric regions of goat autosomes. Sequences complementary to goat satellites I and II hybridize efficiently to centromeric regions of sheep acrocentric autosomes. 5. The large centric fusion chromosomes of the sheep contain few, if any, sequences homologous to sheep or goat satellite I but do contain sequences homol ogous to sheep and goat satellite II, indicating preferential loss of the major highly repetitive DNA (satellite I) in the fused chromosomes of the sheep and conservation of the minor sequence (satellite II). 6. Sex chromosomes of the sheep and goat, as in the calf, contain few, if any, sequences homologous to the eight satellite DNAs studied in the three animals. This may conform to a general pattern of sex chromosomes and highly repetitive DNA sequences throughout the Bovoidea. The cytogenetic implications of these findings in the chromosome evolution of the Bovoidea are discussed.
Characterization of sister chromatid exchange induction by 8-methoxypsoralen plus near UV light
Authors: Latt S.A. , Loveday K.S.
Published: May 2008

The combination of 8-methoxypsoralen and near UV light is highly effective in inducing sister chromatid exchanges (SCEs) in Chinese hamster ovary cells. Appreciable increases in SCEs can be effected by treatments compatible with cell survival, and effects of a single dose of alkylation persist over multiple generations. Both the frequency and location of SCEs induced at different times within the DNA synthesis period varies in a manner indicating that exchange induction is restricted to regions which replicated during or after DNA damage.
Chromosomal evolution in Malagasy lemurs
Authors: Rumpler Y. , Dutrillaux B.
Published: May 2008

The karyotypes of five Malagasy lemurs are described and compared after the successive use of various banding methods. Phylogenic relationships appear to exist between the respective ancestors of Lemur catta, Hapalemur simus, H. griseus occidentalis, H. griseus ssp, and H. griseus griseus. Their karyotypes can be derived from that of L. fulvus fulvus by chromosomal rearrangements affecting mainly chromosomes 1 and X. Intense staining of juxtacentromeric heterochromatin was detected among the different subspecies of H. griseus.
The localization of mouse globin genes: a test of the effectiveness of hybridization in situ
Authors: Henderson A.S. , Yu M.T. , Atwood K.C.
Published: May 2008

Hybridization of rabbit reticulocyte mRNA to banded mouse chromosomes in situ labeled several regions, including the globin loci. Whereas the labeling was sufficient to detect unknowns in the globin size class, the chromosome assignments would be doubtful without some means of removing trace contaminants from the probe or of recognizing chromosomal regions to which they hybridize. Mammalian gene mapping by means of hybridization in situ might be feasible with probes cloned in microbial host-vector systems or with kinetic analysis of the hybridization process at every labeled site.
Automated measurements on human C-bands in family studies
Authors: Mason D.C. , Lauder I.J. , Spowart G.
Published: May 2008

An automated system providing quantitative measurements of C-band size has been used, in conjunction with statistical methodology developed for the purpose, in a family study to demonstrate its potential in determining the mode of transmission of C-bands from parent to offspring, and to test the assumption of Mendelian inheritance. The most serious obstacle encountered was the high within-person variance of the normalized band sizes, the large within-slide variance being increased by technical variation between different preparations. Attempts to reduce variance by developing more effective normalization techniques did not prove fruitful. Nevertheless, the ability of the present system to perform a trace using a reasonable number of cells has been demonstrated in an example. In the two families studied we saw no evidence that band size was not transmitted and changes in band size, if any, were less than about 5 µm2 × 10–2 (compared to a typical medium-category band size of about 65 µm2 x 10–2).
The chromosomes of cockerels (Gallus domesticus) during meiosis
Authors: Pollock D.L. , Fechheimer N.S.
Published: May 2008

The chromosomes in spermatogenic cells of 10 cockerels were examined. Prior to removing the testes, the birds had been injected with either 2.5 mg vinblastine sulfate or 5 mg colchicine, or were untreated. A cell suspension was made from small pieces of testis and slides were prepared using an air-drying technique. Pretreatments of the birds increased the numbers of spermatogonial and secondary spermatocyte cells at metaphase and rendered them more amenable to analysis. The modal number of macrochromosomes or bivalents was observed in 90.2 % of spermatogonia, 98 % of primary spermatocytes at diakinesis, and 94.2 % of secondary spermatocytes. Polyploid cells at all stages were thought to be largely artifacts of the procedure. Aneuploidy was rare, being found in only 1 % of secondary spermatocytes. It is estimated that between 56 and 66 chiasmata occur in the 39 bivalents; of these, an average of 28 are seen in the six macrobivalents. Average numbers were 8.1, 5.9, 4.6, 3.6, 2.4, and 3.5 for macrobivalents 1 through 5 and the Z respectively. The numbers of chiasmata differed significantly among birds but were not differentially affected by pretreatment of the birds.
The replicative life spans of euploid hybrids derived from short-lived and long-lived human skin fibroblast cultures
Authors: Hoehn H. , Bryant E.M. , Martin G.M.
Published: May 2008

Two recent technical advances facilitate the derivation of proliferating hybrids from human diploid fibroblast strains without recourse to biochemical selection: (1) a new chemically-mediated method of somatic cell fusion (PEG-DMSO) yields hybrids at rates as high as 1 in 160 colonies after dilute plating of treated cell mixtures, and (2) a simple technology for assessment of DNA content (flow microfluorometry) permits rapid and highly sensitive monitoring of ploidy. Employing these techniques, we isolated 43 chromosomally stable hybrid clones from 12 crosses between seven different strains representing a wide range of longevities. Crosses between short-lived strains resulted in short-lived hybrid offspring, whereas hybrids derived from long-lived parents tended to be long-lived. Crosses between strains of contrasting longevities gave clones with intermediate growth potentials relative to the other types of hybrids. The failure to observe complementation (enhanced longevity) of hybrids argues against random recessive single-copy gene mutations as important determinants of clonal senescence.
Karyotype evolution of the simian virus 40-transformed human cell line LNSV
Authors: Begovich A. , Francke U.
Published: May 2008

We have used trypsin-Wright’s banding (“GTG-banding”) to analyze the chromosome content in two sublines of the SV40-transformed human cell line LNSV, derived from fibroblasts of a patient with HPRT deficiency. Both LNSV sublines (GM-847 and “LNSV”) were heteroploid and showed considerable numerical and structural chromosome variability. Nineteen rearranged chromosomes which were observed at high frequency have been set aside as “marker chromosomes,” and their probable derivation from normal human chromosomes has been described in Paris Conference (1971) nomenclature. Heterogeneity within these uncloned sublines appears to increase with time in culture, and no evidence was found for evolution of a karyotypically stable cell population. The results are of general significance for cell genetic studies using established cell lines.
Ataxia telangiectasia: chromosomal stability in continuous lymphoblastoid cell lines
Authors: Cohen M.M. , Sagi M. , Ben-Zur Z. , Schaap T. , Voss R. , Kohn G. , Ben-Bassat H.
Published: May 2008

Chromosomal breakage in peripheral lymphocytes, cultured fibroblasts, and long-term lymphoblastoid cell lines was investigated in five hitherto undescribed patients with ataxia telangiectasia (AT). Increased chromosomal instability was observed in lymphocytes and fibroblasts, and clones possessing a Dq+ marker were observed. Breakage rates were significantly higher in the fibroblasts than in the lymphocytes of AT patients or in similar tissues from patients with Bloom syndrome or Fanconi anemia. However, chromosome breakage in lymphoblastoid lines established from these five AT patients and six others did not differ from controls. These observations suggests that selection pressures, in vivo or in vitro, or both, act differently on the expression of chromosomal instability in these various cell types.
Analyses of diplotene chiasma frequencies in mouse oocytes and spermatocytes in relation to ageing and sexual dimorphism
Authors: Jagiello G. , Fang J.S.
Published: May 2008

Diplotene chiasma frequencies from “early” (day 16) fetal oocytes are significantly greater than the average from “late” (day 18) oocytes. A decrease in chiasma frequencies from both ages was found at diakinesis/MI in oocytes of young or old adult females, indicating a loss of chiasmata and/or terminalization. A greater number of type I univalents was found in “late” oocytes than “early” oocytes entering diplotene. No differences were found in chiasma frequencies of male diplotene spermatocytes studied at 23 days, 2 months, or 24 months of age. A greater chiasma frequency was generally found in the female than the male at all ages studied.
Effects of distamycin A on human leukocytes in vitro
Authors: Prantera G. , Pimpinelli S. , Rocchi A.
Published: May 2008

Distamycin A, an oligopeptide antibiotic, supplied at various concentrations for 24 h to human leukocytes in culture, has induced the appearance on some chromosomes of specific areas lacking spiralization. In particular, the centromeric regions of chromosomes 1, 3 and one C-group chromosome and the distal part of the long arm of the Y chromosome were despiralized. The possible nature of these regions is discussed.
Ellobius lutescens, Th. (Rodentia, Microtinae): Q-, R-, and replication banding, patterns
Authors: Wolf M. , Schempp W. , Vogel W.
Published: May 2008

Five specimens of Ellobius lutescens, four males and one female, were studied by several banding methods. Structural polymorphism occurred in the longest chromosome pair of the karyotype of two males: a pericentric inversion in one animal and a paracentric inversion in the other. In the female studied, one chromosome 1 differs from those of the males by a marked elongation of a proximal euchromatic band in the long arm. Thus, the female seems to represent the heterogametic sex. Chromosome 9 showed the same banding pattern in both sexes. The possible meaning of this chromosome constitution for the sex-determining mechanism of E. lutescens is discussed.
Gametic products transmitted by chickens heterozygous for chromosomal rearrangements
Authors: Dinkel B.J. , O’Laughlin-Phillips E.A. , Fechheimer N.S. , Jaap R.G.
Published: May 2008

Chromosomal analysis was made from 3744 chick embryos derived from reciprocal matings between parents, one of which was heterozygous for a pericentric inversion, a centric fission, or one of three translocations. The objectives were to determine the types and frequencies of genetically balanced and unbalanced gametes transmitted to early embryos by rearrangement heterozygotes and to ascertain if some gametic types were preferentially produced or utilized. The array of embryos obtained from the heterozygous sires did not deviate significantly from the expected, except in the case of the centric fission group. Among embryos derived from heterozygous dams, however, significant deviations from the expected 1:1 ratio for complementary gametic products, resulting from specific balanced and unbalanced segregation types, were found consistently in all three translocation groups and the centric fission group (P < 0.025). It was concluded that differences exist between heterozygous sires and dams in the frequencies at which some gametic types are produced. The deviations from the expected ratios among progeny of heterozygous dams may be the result of anaphase lagging during the meiotic division of oogenesis.
Gene dosage effect: intraband mapping of human soluble glutamic oxaloacetic transaminase
Authors: Spritz R.A. , Emanuel B.S. , Chern C.J. , Mellman W.J.
Published: May 2008

Quantitative assays of soluble GOT were performed on fibroblasts (from two individuals) with duplications of the long arm of chromosome 10 (10q24→qter). Improved karyologic technique demonstrated that the duplications differ by half a band. Correlation of GOTs activity with the karyologic data indicates that the structural locus for GOTs maps within band 10q24. This study demonstrates the utility of this approach to fine structural mapping of the human genome.
On the chromosomal location of 5.8S DNA in people and mice
Authors: Henderson A.S. , Yu M.T. , Milcarek C.
Published: May 2008

The genes that transcribe 5.8S RNA in people and mice have been localized to the previously assigned sites for ribosomal DNA. No other sites of transcription for 5.8S RNA were detected.
Asymptomatic Peripheral Arterial Disease Is Associated With More Adverse Lower Extremity Characteristics Than Intermittent Claudication
Authors: McDermott Mary M. , Guralnik Jack M. , Ferrucci Luigi , Tian Lu , Liu Kiang , Liao Yihua , Green David , Sufit Robert , Hoff Frederick , Nishida Takashi , Sharma Leena , Pearce William H. , Schneider Joseph R. , Criqui Michael H.
Published: May 2008

Background—

This study assessed functional performance, calf muscle characteristics, peripheral nerve function, and quality of life in asymptomatic persons with peripheral arterial disease (PAD).

Methods and Results—

PAD participants (n=465) had an ankle brachial index <0.90. Non-PAD participants (n=292) had an ankle brachial index of 0.90 to 1.30. PAD participants were categorized into leg symptom groups including intermittent claudication (n=215) and always asymptomatic (participants who never experienced exertional leg pain, even during the 6-minute walk; n=72). Calf muscle was measured with computed tomography. Analyses were adjusted for age, sex, race, ankle brachial index, comorbidities, and other confounders. Compared with participants with intermittent claudication, always asymptomatic PAD participants had smaller calf muscle area (4935 versus 5592 mm
2
;
P
<0.001), higher calf muscle percent fat (16.10% versus 9.45%;
P
<0.001), poorer 6-minute walk performance (966 versus 1129 ft;
P
=0.0002), slower usual-paced walking speed (
P
=0.0019), slower fast-paced walking speed (
P
<0.001), and a poorer Short-Form 36 Physical Functioning score (
P
=0.016). Compared with an age-matched, sedentary, non-PAD cohort, always asymptomatic PAD participants had smaller calf muscle area (5061 versus 5895 mm
2
;
P
=0.009), poorer 6-minute walk performance (1126 versus 1452 ft;
P
<0.001), and poorer Walking Impairment Questionnaire speed scores (40.87 versus 57.78;
P
=0.001).

Conclusions—

Persons with PAD who never experience exertional leg symptoms have poorer functional performance, poorer quality of life, and more adverse calf muscle characteristics compared with persons with intermittent claudication and a sedentary, asymptomatic, age-matched group of non-PAD persons.
Selective Vacuolar Degeneration in Dystrophin-Deficient Canine Purkinje Fibers Despite Preservation of Dystrophin-Associated Proteins With Overexpression of Dp71
Authors: Urasawa Nobuyuki , Wada Michiko R. , Machida Noboru , Yuasa Katsutoshi , Shimatsu Yoshiki , Wakao Yoshito , Yuasa Shigeki , Sano Toshiaki , Nonaka Ikuya , Nakamura Akinori , Takeda Shin’ichi
Published: May 2008

Background—

Respiratory support therapy significantly improves life span in patients with Duchenne muscular dystrophy; cardiac-related fatalities, including lethal arrhythmias, then become a crucial issue. It is therefore important to more thoroughly understand cardiac involvement, especially pathology of the conduction system, in the larger Duchenne muscular dystrophy animal models such as dystrophic dogs.

Methods and Results—

When 10 dogs with canine X-linked muscular dystrophy in Japan (CXMD
J
) were examined at the age of 1 to 13 months, dystrophic changes of the ventricular myocardium were not evident; however, Purkinje fibers showed remarkable vacuolar degeneration as early as 4 months of age. The degeneration of CXMD
J
Purkinje fibers was coincident with overexpression of Dp71 at the sarcolemma and translocation of μ-calpain to the cell periphery near the sarcolemma or in the vacuoles. Immunoblotting of the microdissected fraction showed that μ-calpain–sensitive proteins such as desmin and cardiac troponin-I or -T were selectively degraded in the CXMD
J
Purkinje fibers. Utrophin was highly upregulated in the earlier stage of CXMD
J
Purkinje fibers, but the expression was dislocated when vacuolar degeneration was recognized at 4 months of age. Nevertheless, the expression of dystrophin-associated proteins α-, β-, γ-, and δ-sarcoglycans and β-dystroglycan was well maintained at the sarcolemma of Purkinje fibers.

Conclusions—

Selective vacuolar degeneration of Purkinje fibers was found in the early stages of dystrophin deficiency. Dislocation of utrophin besides upregulation of Dp71 can be involved with this pathology. The degeneration of Purkinje fibers can be associated with the distinct deep Q waves in ECG and fatal arrhythmia seen in dystrophin deficiency.
Results of the Predictors of Response to CRT (PROSPECT) Trial
Authors: Chung Eugene S. , Leon Angel R. , Tavazzi Luigi , Sun Jing-Ping , Nihoyannopoulos Petros , Merlino John , Abraham William T. , Ghio Stefano , Leclercq Christophe , Bax Jeroen J. , Yu Cheuk-Man , Gorcsan John , St John Sutton Martin , De Sutter Johan , Murillo Jaime
Published: May 2008

Background—

Data from single-center studies suggest that echocardiographic parameters of mechanical dyssynchrony may improve patient selection for cardiac resynchronization therapy (CRT). In a prospective, multicenter setting, the Predictors of Response to CRT (PROSPECT) study tested the performance of these parameters to predict CRT response.

Methods and Results—

Fifty-three centers in Europe, Hong Kong, and the United States enrolled 498 patients with standard CRT indications (New York Heart Association class III or IV heart failure, left ventricular ejection fraction ≤35%, QRS ≥130 ms, stable medical regimen). Twelve echocardiographic parameters of dyssynchrony, based on both conventional and tissue Doppler–based methods, were evaluated after site training in acquisition methods and blinded core laboratory analysis. Indicators of positive CRT response were improved clinical composite score and ≥15% reduction in left ventricular end-systolic volume at 6 months. Clinical composite score was improved in 69% of 426 patients, whereas left ventricular end-systolic volume decreased ≥15% in 56% of 286 patients with paired data. The ability of the 12 echocardiographic parameters to predict clinical composite score response varied widely, with sensitivity ranging from 6% to 74% and specificity ranging from 35% to 91%; for predicting left ventricular end-systolic volume response, sensitivity ranged from 9% to 77% and specificity from 31% to 93%. For all the parameters, the area under the receiver-operating characteristics curve for positive clinical or volume response to CRT was ≤0.62. There was large variability in the analysis of the dyssynchrony parameters.

Conclusion—

Given the modest sensitivity and specificity in this multicenter setting despite training and central analysis, no single echocardiographic measure of dyssynchrony may be recommended to improve patient selection for CRT beyond current guidelines. Efforts aimed at reducing variability arising from technical and interpretative factors may improve the predictive power of these echocardiographic parameters in a broad clinical setting.
Adverse Cardiovascular Effects of Acute Salt Loading in Young Normotensive Individuals
Authors: Tzemos Nikolaos , Lim Pitt O. , Wong Suzanne , Struthers Allan D. , MacDonald Thomas M.
Published: May 2008

We sought to explore the effects of salt loading in young normotensives on vascular endothelial function, echocardiographic left ventricular diastolic function, and electrocardiographic QT dispersion. Sixteen healthy normotensive male volunteers were randomized in a double-blind crossover fashion to 5-day treatment periods with either placebo or salt tablets (200 mmol/d of sodium) separated by a 2-week washout period. Throughout the study the volunteers were asked to maintain a low-salt diet. Forearm venous occlusion plethysmography and intraarterial infusions of acetylcholine (ACh), sodium nitroprusside (SNP), and
N
G
-monomethyl-
l
-arginine (L-NMMA) were used to assess vascular reactivity. Baseline and postsalt loading 12-lead ECGs and echocardiograms were also obtained. Twenty-four-hour ambulatory systolic blood pressure rose (117±11 to 121±8 mm Hg) significantly with salt loading. The endothelium-dependent responses to ACh were significantly blunted with salt compared to placebo (ΔFBF% 403 [50] versus 296 [31];
P
<0.05) and L-NMMA (ΔFBF% −47.2 [4] versus −31 [3];
P
<0.01). In contrast, the endothelium-independent response to SNP was not different between treatments. Color M-mode flow propagation velocity (CMMFPV), a preload index of left ventricular diastolic function, was significantly reduced with salt (64 [6] versus 59 [16] cm/s;
P
<0.05) suggesting increased ventricular stiffness. QT dispersion was also significantly increased with salt (58 [16] versus 48 [17] ms;
P
=0.02). Salt loading impaired vascular endothelial function, left ventricular mechanical relaxation, and electric repolarization in young healthy normotensives.
Diurnal Characteristics of Precipitation Features over the Tropical East Pacific: A Comparison of the EPIC and TEPPS Regions
Authors: Cifelli R. , Nesbitt S. W. , Rutledge S. A. , Petersen W. A. , Yuter S.
Published: May 2008

This study examines the diurnal cycle of precipitation features in two regions of the tropical east Pacific where field campaigns [the East Pacific Investigation of Climate Processes in the Coupled Ocean–Atmosphere System (EPIC) and the Tropical Eastern Pacific Process Study (TEPPS)] were recently conducted. EPIC (10°N, 95°W) was undertaken in September 2001 and TEPPS (8°N, 125°W) was carried out in August 1997. Both studies employed C-band radar observations on board the NOAA ship Ronald H. Brown (RHB) and periodic upper-air sounding launches to observe conditions in the surrounding environment. Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) and Geostationary Operational Environmental Satellite (GOES) IR data are used to place the RHB data in a climatological context and Tropical Atmosphere Ocean (TAO) buoy data are used to evaluate changes in boundary layer fluxes in context with the observed diurnal cycle of radar observations of precipitation features.

Precipitation features are defined as contiguous regions of radar echo and are subdivided into mesoscale convective system (MCS) and sub-MCS categories. Results show that MCSs observed in EPIC and TEPPS have distinct diurnal signatures. Both regions show an increase in intensity starting in the afternoon hours, with the timing of maximum rain intensity preceding maxima in rain area and accumulation. In the TEPPS region, MCS rain rates peak in the evening and rain area and accumulation in the late night–early morning hours. In contrast, EPIC MCS rain rates peak in the late night–early morning, and rain area and accumulation are at a maximum near local sunrise. The EPIC observations are in agreement with previous satellite studies over the Americas, which show a phase lag response in the adjacent oceanic regions to afternoon–evening convection over the Central American landmass. Sub-MCS features in both regions have a broad peak extending through the evening to late night–early morning hours, similar to that for MCSs. During sub-MCS-only periods, the rainfall patterns of these features are closely linked to diurnal changes in SST and the resulting boundary layer flux variability.
Diurnal Cycles of Clouds and How They Affect Polar-Orbiting Satellite Data
Authors: Wylie Donald
Published: May 2008

Diurnal cycles of clouds were investigated using the NOAA series of polar-orbiting satellites. These satellites provided four observations per day for a continuous 11-yr period from 1986 to 1997. The High Resolution Infrared Radiation Sounder (HIRS) multispectral infrared data were used from the time trend analysis of Wylie et al. The previous study restricted its discussion to only the polar orbiters making observations at 0200 and 1400 LT because gaps in coverage occurred in the 0800 and 2000 LT coverage. This study shows diurnal cycles in cloud cover over 10% in amplitude in many regions, which is very similar to other studies that used geostationary satellite data. The use of only one of the polar-orbiting satellites by Wylie et al. caused biases up to 5% in small regions but in general they were small (e.g., ≤2% for most of the earth). The only consistently large bias was in high cloud cover over land in North America, Europe, and Asia north of 35°N latitude in the summer season where the 0200 and 1400 LT average high cloud frequency was 2%–5% more than the daily average. This occurred only in the summer season, not in the winter.
On the Strong Seasonal Currents in the Deep Ocean
Authors: Saenko Oleg A.
Published: May 2008

Using a set of models, including one with a resolution of ¼°, several aspects of the simulated seasonal currents in the deep ocean are considered. It is shown that over vast areas of the deep interior, particularly in the Indian Ocean, annual-mean circulation represents a small residual of much stronger seasonal flows. In many places the seasonal horizontal velocities are of the order of 10−2 m s−1, reaching locally to 10−1 m s−1; the corresponding vertical velocities are of the order of 10−5 m s−1. An idealized geometry model is employed to confirm the notion that much of this seasonal variability in the deep-ocean circulation can be attributed to the annual cycle of wind stress, combined with the significant increase in the vertical trapping depth for basin-scale seasonal forcing. It is suggested that, at least on seasonal time scales, the so-called bottom pressure torque can be an important term in the depth-integrated vorticity balance. An interaction of these relatively strong flows (of nontidal origin) with bottom topography may contribute to diapycnal mixing in the deep ocean in a manner similar to that proposed recently for the Southern Ocean. In addition, it is found that under a plausible climate change scenario, the amplitude of the mean annual cycle of wind stress may change. Among the regions where such changes are most pronounced is that in the extratropical North Pacific. It is shown that the data on surface wind stress can be effectively used to identify the seasons with the largest changes in the deep-reaching overturning cells. Finally, unlike what might be expected from the earlier theories, the annual-mean circulation simulated by the model with ¼° resolution has the deep interior flows that tend to group into jetlike structures, often having a predominant equatorward rather than poleward direction.
Friction, Frontogenesis, and the Stratification of the Surface Mixed Layer
Authors: Thomas Leif , Ferrari Raffaele
Published: May 2008

The generation and destruction of stratification in the surface mixed layer of the ocean is understood to result from vertical turbulent transport of buoyancy and momentum driven by air–sea fluxes and stresses. In this paper, it is shown that the magnitude and penetration of vertical fluxes are strongly modified by horizontal gradients in buoyancy and momentum. A classic example is the strong restratification resulting from frontogenesis in regions of confluent flow. Frictional forces acting on a baroclinic current either imposed externally by a wind stress or caused by the spindown of the current itself also modify the stratification by driving Ekman flows that differentially advect density. Ekman flow induced during spindown always tends to restratify the fluid, while wind-driven Ekman currents will restratify or destratify the mixed layer if the wind stress has a component up or down front (i.e., directed against or with the geostrophic shear), respectively. Scalings are constructed for the relative importance of friction versus frontogenesis in the restratification of the mixed layer and are tested using numerical experiments of mixed layer fronts forced by both winds and a strain field. The scalings suggest and the numerical experiments confirm that for wind stress magnitudes, mixed layer depths, and cross-front density gradients typical of the ocean, wind-induced friction often dominates frontogenesis in the modification of the stratification of the upper ocean. The experiments reveal that wind-induced destratification is weaker in magnitude than restratification because the stratification generated by up-front winds confines the turbulent stress to a depth shallower than the Ekman layer, which enhances the frictional force, Ekman flow, and differential advection of density. Frictional destratification is further reduced over restratification because the stress associated with the geostrophic shear at the surface tends to compensate a down-front wind stress.
A Statistical Evaluation of GOES Cloud-Top Properties for Nowcasting Convective Initiation
Authors: Mecikalski John R. , Bedka Kristopher M. , Paech Simon J. , Litten Leslie A.
Published: May 2008

The goal of this project is to validate and extend a study by Mecikalski and Bedka that capitalized on information the Geostationary Operational Environmental Satellite (GOES) instruments provide for nowcasting (i.e., 0–1-h forecasting) convective initiation through the real-time monitoring of cloud-top properties for moving cumuli. Convective initiation (CI) is defined as the first occurrence of a ≥35-dBZ radar echo from a cumuliform cloud. Mecikalski and Bedka’s study concluded that eight infrared GOES-based “interest fields” of growing cumulus clouds should be monitored over 15–30-min intervals toward predicting CI: the transition of cloud-top brightness temperature to below 0°C, cloud-top cooling rates, and instantaneous and time trends of channel differences 6.5–10.7 and 13.3–10.7 μm. The study results are as follows: 1) measures of accuracy and uncertainty of Mecikalski and Bedka’s algorithm via commonly used skill scoring procedures, and 2) a report on the relative importance of each interest field to nowcasting CI using GOES. It is found that for nonpropagating convective events, the skill scores are dependent on which CI interest fields are considered per pixel and are optimized when three–four fields are met for a given 1-km GOES pixel in terms of probability of detection, and threat and Heidke skill scores. The lowest false-alarm rates are found when one field is used: that associated with cloud-top glaciation 30 min prior to CI. Subsequent recommendations for future research toward improving Mecikalski and Bedka’s study are suggested especially with regard to constraining CI nowcasts when inhibiting factors are present (e.g., capping inversions).
Katrina Cataclysm
Authors: Adeola Francis O.
Published: May 2008

This study explores the extent to which people's prior experience of a natural disaster influenced subsequent behavior concerning the threats of a hydrometeorological disaster and if duration of residency in a disaster-prone landscape affects the extent of preparedness for an impending disaster. Mixed methods research strategies involving survey, field observation, and participant observations at several locations including rescue and evacuation centers in New Orleans, Louisiana, Austin, Texas, and Lawrenceville, Georgia, were used, during the immediate impact phase, emergency shelter phase, and postimpact and recovery phase of Katrina catastrophe. For the survey, a sample of 598 subjects completed a 15-page, 54-item questionnaire addressing various aspects of the Katrina flood in the New Orleans Metropolitan Area. The qualitative aspect consists of field observations of the event, interviews, and direct comments by the victims dispersed across the South. In the regression analysis performed, prior experience was found to be less important than friends' and family members' influence in determining evacuation behavior. However, duration of residency and prior experience were found to be slightly significant in predicting the odds of evacuation.
Investigation of IRT-Based Equating Methods in the Presence of Outlier Common Items
Authors: Huiqin Hu  , Rogers W. Todd , Vukmirovic Zarko
Published: May 2008

Common items with inconsistent b-parameter estimates may have a serious impact on item response theory (IRT)—based equating results. To find a better way to deal with the outlier common items with inconsistent b-parameters, the current study investigated the comparability of 10 variations of four IRT-based equating methods (i.e., concurrent calibration, separate calibration with test characteristic curve [TCC] and mean/sigma [M/S] transformations, and calibration with fixed common item parameters [FCIP]) when outliers were either ignored or considered. Simulated data were generated for the common-item nonequivalent groups matrix design to reflect the manipulated factors: group ability differences and nonequivalent groups, number/score points of outliers, and types of outliers. When no outliers were present, the TCC and M/S transformations performed the best. When there were outliers, overall, the methods that considered them (except the M/S transformation with outliers weighted) resulted in a vast improvement compared to the methods that ignored them.
Consistent Estimation of Rasch Item Parameters and Their Standard Errors Under Complex Sample Designs
Authors: Cohen Jon , Chan Tsze , Tao Jiang  , Seburn Mary
Published: May 2008

U.S. state educational testing programs administer tests to track student progress and hold schools accountable for educational outcomes. Methods from item response theory, especially Rasch models, are usually used to equate different forms of a test. The most popular method for estimating Rasch models yields inconsistent estimates and relies on ad hoc adjustments to obtain good approximations. Furthermore, psychometricians have paid little attention to the estimation of effective standard errors for Rasch models, especially under complex sample designs. This article presents a computationally efficient, statistically consistent estimator for Rasch models, based on a nonparametric marginal maximum likelihood approach, along with complete, design-consistent estimators of the standard error, based on the full information matrix and including covariance terms among items, covariances between items, and parameters of the distribution of the latent trait. Simulations support the consistency of the estimators in both simple random samples and more realistic multistage samples.
Cognitive Diagnostic Attribute-Level Discrimination Indices
Authors: Henson Robert , Roussos Louis , Douglas Jeff , Xuming He
Published: May 2008

Cognitive diagnostic models (CDMs) model the probability of correctly answering an item as a function of an examinee's attribute mastery pattern. Because estimation of the mastery pattern involves more than a continuous measure of ability, reliability concepts introduced by classical test theory and item response theory do not apply. The cognitive diagnostic index (CDI) measures an item's overall discrimination power, which indicates an item's usefulness in examinee attribute pattern estimation. Because of its relationship with correct classification rates, the CDI was shown to be instrumental in cognitively diagnostic test assembly. This article generalizes the CDI to attribute-level discrimination indices for an item. Two different attribute-level discrimination indices are defined; their relationship with correct classification rates is explored using Monte Carlo simulations. There are strong relationships between the defined attribute indices and correct classification rates. Thus, one important potential application of these indices is test assembly from a CDM-calibrated item bank.
How Do Firms Learn to Make Acquisitions? A Review of Past Research and an Agenda for the Future
Authors: Barkema Harry G. , Schijven Mario
Published: May 2008

How do firms learn to successfully acquire other firms? The authors first review early work, mostly from the 1980s to the mid-1990s, testing the learning curve perspective on acquisitions and exploring some contingencies. They then discuss three more recent streams of research on negative experience transfer, deliberate learning mechanisms, and learning from others, which provide deeper insight into the contingencies and mechanisms of organizational learning in strategic settings such as acquisitions. The article concludes with an agenda for future research.
Effects of Political Framing and Perceiver's Social Position on Trait Attributions of a Terrorist/Freedom Fighter
Authors: Montiel Cristina Jayme , Shah Ashiq Ali
Published: May 2008

Positioning theory was invoked to predict that framing effects of political violence are moderated by the social position of the message receiver. As a reference, for the purpose of this study, the societal structural configurations of Malay Muslims and Filipino Christians led to their classification as respondents from the Dominant Social Position, and Malay Christians and Filipino Muslims as participants in the Nondominant Social Position, respectively. Respondents read a vignette about either a terrorist or a freedom fighter who bombed a building, and then described the story character using trait attributes on a semantic differential scale. Respondents from disadvantaged groups preferred freedom fighters over terrorists, whereas respondents from dominant groups evaluated terrorists more highly than freedom fighters.
Daily Physical Activity: Relation to Everyday Memory in Adulthood
Authors: Whitbourne Stacey B. , Neupert Shevaun D. , Lachman Margie E.
Published: May 2008

This article examines the relationship between daily physical activity and everyday memory using an 8-day diary design with young, middle-aged, and older adults. Contrary to expectations, age differences were not reported in the frequency of memory failures and daily physical activity at the between-person level. Multilevel modeling, however, indicated that on days when adults engaged in leisure exercise (physical activity performed during leisure or free time), they reported fewer memory failures, and this was most apparent for older adults. Lagged analyses indicated that when leisure activity was reported on one day, fewer memory failures were reported the next day, and this was especially true for older adults. Thus, findings demonstrate that the benefits of physical activity for memory in later life are observable on a short-term daily basis.
Caregiving Burden, Community Services, and Quality of Life of Primary Caregivers of Frail Elderly Persons
Authors: Iecovich Esther
Published: May 2008

Caregiving burden was found to be affected by a multiplicity of factors and to affect the quality of life of family caregivers. The present study is aimed at examining the extent to which various supportive services help to alleviate caregivers' burden and the extent to which caregivers' burden affects various domains of the quality of life of primary caregivers and also to investigate the factors that best explain quality of life. The sample includes 114 primary caregivers who provided care to physically disabled elderly family members. Data were collected through face-to-face interviews. The findings show that various domains of the quality of life of primary caregivers were affected by the level of the caregivers' burden and the types of services provided to the elderly person, by caregivers' characteristics, as well as their health and economic status.
Unemployment Among Women
Authors: Kimerling Rachel , Alvarez Jennifer , Pavao Joanne , Mack Katelyn P. , Smith Mark W. , Baumrind Nikki
Published: May 2008

Prior research has demonstrated that intimate partner violence (IPV) is associated with employment instability among poor women. The current study assesses the broader relationship between IPV and women's workforce participation in a population-based sample of 6,698 California women. We examined past-year IPV by analyzing specific effects of physical violence, psychological violence, and posttraumatic stress disorder (PTSD) symptoms as predictors of unemployment. Results indicated substantial rates of unemployment among women who reported IPV, with rates of 20% among women who experienced psychological violence, 18% among women who experienced physical violence, and 19% among women with PTSD symptoms. When the relationship was adjusted for demographic characteristics and educational attainment, PTSD (adjusted odds ratio [AOR] = 1.60; 95% confidence interval [CI] = 1.22, 2.09) and psychological violence (AOR = 1.78; 95% CI = 1.36, 2.32), but not physical violence, were associated with unemployment. Implications for supported employment programs and workplace responses to IPV are discussed.
Belonging, Behaving, and Believing
Authors: Olson Laura R. , Warber Adam L.
Published: May 2008

We operationalize three dimensions of religion—religious affiliation, religious commitment, and religious belief—to offer a detailed analysis of how religion affects presidential approval ratings. Using data from the 1992, 1996, 2000, and 2004 American National Election Studies, we demonstrate that operationalizing religion as a rudimentary Protestant—Catholic affiliation dichotomy masks its influence on presidential approval. We find that religious affiliation, even when measured more precisely than with a Protestant—Catholic dichotomy, contributes less to models of presidential approval than do measures of religious commitment and (especially) orthodoxy of religious belief.
Case Selection Techniques in Case Study Research
Authors: Seawright Jason , Gerring John
Published: May 2008

How can scholars select cases from a large universe for in-depth case study analysis? Random sampling is not typically a viable approach when the total number of cases to be selected is small. Hence attention to purposive modes of sampling is needed. Yet, while the existing qualitative literature on case selection offers a wide range of suggestions for case selection, most techniques discussed require in-depth familiarity of each case. Seven case selection procedures are considered, each of which facilitates a different strategy for within-case analysis. The case selection procedures considered focus on typical, diverse, extreme, deviant, influential, most similar, and most different cases. For each case selection procedure, quantitative approaches are discussed that meet the goals of the approach, while still requiring information that can reasonably be gathered for a large number of cases.
The Political Resocialization of Immigrants
Authors: White Stephen , Nevitte Neil , Blais André , Gidengil Elisabeth , Fournier Patrick
Published: May 2008

Theories of political socialization contain competing expectations about immigrants' potential for political resocialization. Premigration beliefs and actions may be resistant to change, exposure to the new political system may facilitate adaptation, or immigrants may find ways to transfer beliefs and behaviors from one political system to another. This analysis empirically tests these three alternative theories of resocialization. The results indicate that both transfer and exposure matter; there is little evidence that premigration beliefs and actions are resistant to change. Moreover, how immigrants adapt depends on which orientation or behavior is being considered and on what kind of political environments migrants come from.
Occupational Representations of Workers in Nonstandard and Precarious Work Situations
Authors: Bujold Charles , Fournier Geneviève
Published: May 2008

The mental representations of employment precariousness, occupational success, and work were examined in a sample of 124 White Canadian francophones (62 men, 62 women) who had experienced nonstandard and precarious work for the last 3 years. Typologies of each of these representations were derived from the content analysis of the data collected through semistructured individual interviews. The results of this study are consistent with the literature, indicating that nonstandard and precarious workers do not constitute a monolithic population. Convergences, as well as diversity, were observed in the various representations. Besides, whereas the participants' representations of employment precariousness were mostly negative, those of occupational success and work bore witness to a rather hopeful conception of work life. The results are discussed with respect to the scientific literature and to the differences that were found between genders, age groups, and educational levels. Implications for career counseling and future research are provided.
Life in So Many Acts
Authors: Moreira Claudio
Published: May 2008

In this piece, drawing from performance autoethnography, third world feminism, and postcolonial/cultural studies, the author interrogates “how do I play scholar?” The author uses Judith Butler's question “how do I play gender?” and her notions of performativity to dance around, using the voices of the “Thug” and the “Scholar,” in a quest for a performative scholarship that honors the author's commitment with social justice and at the same time, does not make his life unlivable. The author argues for the need for a decolonizing form of inquiry that includes not only the stories but also the bodies and visceral knowledge of the oppressed in the academic production of knowledge. From the borders the author have lived, labored, and crossed, he presents his life in acts, fighting for a better and just world.