bluuebunny/crossref_metadata_2025 huggingface dataset:
Estrogen replacement suppresses stress-induced cardiovascular responses in ovariectomized rats
Authors: Morimoto Keiko , Kurahashi Youko , Shintani-Ishida Kaori , Kawamura Natsuko , Miyashita Mariko , Uji Masami , Tan Nobusuke , Yoshida Ken-ichi
Published: July 2004

We assessed the hypothesis that chronic estrogen replacement in ovariectomized rats has the beneficial effect of suppressing stress-induced cardiovascular responses through endothelial nitric oxide synthase (eNOS). We employed a radiotelemetry system to measure blood pressure and heart rate (HR). Female Wistar rats aged 11 wk were ovariectomized and implanted with radiotelemetry devices. After 4 wk, the rats were assigned either to a placebo-treated group (Placebo; n = 6) or a group treated with 17β-estradiol (Estrogen; n = 8) subcutaneously implanted with either placebo- or 17β-estradiol (1.5 mg/60-day release) pellets under anesthesia. These rats underwent either of the two types of stress after 4 wk of estrogen or placebo treatment. Cage-switch stress and restraint stress rapidly and continuously elevated the mean arterial pressure (MAP) and HR both in the Placebo and Estrogen groups. However, the MAP and HR responses to cage-switch stress and the MAP but not HR response to restraint stress were attenuated significantly in the Estrogen group compared with the Placebo group. A NOS inhibitor, NG-nitro-l-arginine methyl ester, given in drinking water, reduced the difference in the pressor response to cage-switch between the Estrogen and Placebo groups. In addition, Western blot analysis showed that eNOS expression in the mesentery was increased in the Estrogen group compared with the Placebo group. Thus for the first time we showed that mesenteric eNOS overexpression could explain at least partly why chronic estrogen treatment suppressed the enhanced cardiovascular responses to psychological stress in the ovariectomized rat.
Left ventricular pressure-volume relationship in a rat model of advanced aging-associated heart failure
Authors: Pacher Pál , Mabley Jon G. , Liaudet Lucas , Evgenov Oleg V. , Marton Anita , Haskó György , Kollai Márk , Szabó Csaba
Published: July 2004

Aging is associated with profound changes in the structure and function of the heart. A fundamental understanding of these processes, using relevant animal models, is required for effective prevention and treatment of cardiovascular disease in the elderly. Here, we studied cardiac performance in 4- to 5-mo-old (young) and 24- to 26-mo-old (old) Fischer 344 male rats using the Millar pressure-volume (P-V) conductance catheter system. We evaluated systolic and diastolic function in vivo at different preloads, including preload recruitable stroke work (PRSW), maximal slope of the systolic pressure increment (+dP/d t), and its relation to end-diastolic volume (+dP/d t-EDV) as well as the time constant of left ventricular pressure decay, as an index of relaxation. The slope of the end-diastolic P-V relation (EDPVR), an index of left ventricular stiffness, was also calculated. Aging was associated with decrease in left ventricular systolic pressure, +dP/d t, maximal slope of the diastolic pressure decrement, +dP/d t-EDV, PRSW, ejection fraction, stroke volume, cardiac and stroke work indexes, and efficiency. In contrast, total peripheral resistance, left ventricular end-diastolic volume, left ventricular end-diastolic pressure, and EDPVR were greater in aging than in young animals. Taken together, these data suggest that advanced aging is characterized by decreased systolic performance accompanied by delayed relaxation and increased diastolic stiffness of the heart in male Fischer 344 rats. P-V analysis is a sensitive method to determine cardiac function in rats.
Test of dynamic closed-loop baroreflex and autoregulatory control of total peripheral resistance in intact and conscious sheep
Authors: Aljuri Nikolai , Marini Robert , Cohen Richard J.
Published: July 2004

This is the first study able to examine and delineate the actual actions of the physiological mechanisms responsible for the dynamic couplings between cardiac output (CO), arterial pressure (Pa), right atrial pressure (PRA), and total peripheral resistance (TPR) in an individual subject without altering the underlying regulatory mechanisms. Eight conscious male sheep were used, where both types of baroreceptors were independently exposed to simultaneous beat-to-beat pressure perturbations under intact closed-loop conditions while CO, Pa, PRA, and TPR were measured. We applied the cardiovascular system identification method proposed in a companion paper ( 4 ) to quantitatively characterize the dynamic closed-loop transfer relations CO→Pa, PRA→Pa, Pa→TPR, and PRA→TPR from the measured signals. To validate the dynamic properties of the estimated transfer relations, the essential parts of the linear dynamics of the model were independently and comprehensively evaluated via error model cross-validation, and the overall model's steady-state behavior was compared with a separate random effects regression approach. In addition to numerous physiological findings, we found that the cardiovascular system identification results were exceptionally consistent with the analytically derived solutions previously discussed in Ref. 4 . In conclusion, this study presents the first time validation of a cardiovascular system identification method by means of experimentally acquired animal data in the intact and conscious animal and offers a set of powerful quantitative tools essential to advancing our knowledge of cardiovascular regulatory physiology.
Degranulation of mast cells located in median eminence in response to compound 48/80 evokes adrenocortical secretion via histamine and CRF in dogs
Authors: Matsumoto Itsuro , Inoue Yasuhisa , Tsuchiya Katsuhiko , Shimada Toshio , Aikawa Tadaomi
Published: July 2004

The effect of intracerebroventricular infusion of compound 48/80 (C48/80), a mast cell secretagogue, on adrenal cortisol secretion was investigated in dogs under pentobarbital sodium anesthesia. A marked increase in adrenal cortisol secretion was elicited by C48/80 along with a concomitant increase in the plasma levels of cortisol and immunoreactive ACTH, but neither arterial blood pressure and heart rate nor the plasma histamine level altered significantly. Pretreatment with either anti-CRF antiserum or pyrilamine maleate (H1histamine-receptor antagonist) significantly attenuated the C48/80-evoked increase in cortisol secretion, but pretreatment with metiamide (H2-receptor antagonist) significantly potentiated it. Significant attenuation of the C48/80-evoked increase in cortisol also occurred in dogs given ketotifen, a mast cell stabilizing drug, before pharmacologic challenge. In the pars tuberalis and median eminence (ME), mast cells were highly concentrated in close association with the primary plexus of the hypophysial portal system. Degranulated mast cells were extensively found in the ME of C48/80-treated animals. These results suggest that mast cells located in these regions liberated histamine within the brain as a result of degranulation induced by C48/80 and that this led to activation of the hypothalamic-pituitary-adrenocortical axis.
Effect of heliox on lung dynamic hyperinflation, dyspnea, and exercise endurance capacity in COPD patients
Authors: Palange Paolo , Valli Gabriele , Onorati Paolo , Antonucci Rosa , Paoletti Patrizia , Rosato Alessia , Manfredi Felice , Serra Pietro
Published: July 2004

We tested the hypothesis that heliox breathing, by reducing lung dynamic hyperinflation (DH) and dyspnea (Dys) sensation, may significantly improve exercise endurance capacity in patients with chronic obstructive pulmonary disease [ n = 12, forced expiratory volume in 1 s = 1.15 (SD 0.32) liters]. Each subject underwent two cycle ergometer high-intensity constant work rate exercises to exhaustion, one on room air and one on heliox (79% He-21% O2). Minute ventilation (V̇e), carbon dioxide output, heart rate, inspiratory capacity (IC), Dys, and arterial partial pressure of CO2 were measured. Exercise endurance time increased significantly with heliox [9.0 (SD 4.5) vs. 4.2 (SD 2.0) min; P < 0.001]. This was associated with a significant reduction in lung DH at isotime (Iso), as reflected by the increase in IC [1.97 (SD 0.40) vs. 1.77 (SD 0.41) liters; P < 0.001] and a decrease in Dys [6 (SD 1) vs. 8 (SD 1) score; P < 0.001]. Heliox induced a state of relative hyperventilation, as reflected by the increase in V̇e [38.3 (SD 7.7) vs. 35.5 (SD 8.8) l/min; P < 0.01] and V̇e/carbon dioxide output [36.3 (SD 6.0) vs. 33.9 (SD 5.6); P < 0.01] at peak exercise and by the reduction in arterial partial pressure of CO2 at Iso [44 (SD 6) vs. 48 (SD 6) Torr; P < 0.05] and at peak exercise [46 (SD 6) vs. 48 (SD 6) Torr; P < 0.05]. The reduction in Dys at Iso correlated significantly ( R = −0.75; P < 0.01) with the increase in IC induced by heliox. The increment induced by heliox in exercise endurance time correlated significantly with resting increment in resting forced expiratory in 1 s ( R = 0.88; P < 0.01), increase in IC at Iso ( R = 0.70; P < 0.02), and reduction in Dys at Iso ( R = −0.71; P < 0.01). In chronic obstructive pulmonary disease, heliox breathing improves high-intensity exercise endurance capacity by increasing maximal ventilatory capacity and by reducing lung DH and Dys.
Progression of kyphosis in mdx mice
Authors: Laws Nicola , Hoey Andrew
Published: July 2004

Spinal deformity in the form of kyphosis or kyphoscoliosis occurs in most patients with Duchenne muscular dystrophy (DMD), a fatal X-linked disorder caused by an absence of the subsarcolemmal protein dystrophin. Mdx mice, which also lack dystrophin, show thoracolumbar kyphosis that progresses with age. We hypothesize that paraspinal and respiratory muscle weakness and fibrosis are associated with the progression of spinal deformity in this mouse model, and similar to DMD patients there is evidence of altered thoracic conformation and area. We measured kyphosis in mdx and age-matched control mice by monthly radiographs and the application of a novel radiographic index, the kyphotic index, similar to that used in boys with DMD. Kyphotic index became significantly less in mdx at 9 mo of age (3.58 ± 0.12 compared with 4.27 ± 0.04 in the control strain; P ≤ 0.01), indicating more severe kyphosis, and remained less from 10 to 17 mo of age. Thoracic area in 17-mo-old mdx was reduced by 14% compared with control mice ( P ≤ 0.05). Peak tetanic tension was significantly lower in mdx and fell 47% in old mdx latissimus dorsi muscles, 44% in intercostal strips, and 73% in diaphragm strips ( P ≤ 0.05). Fibrosis of these muscles and the longissimus dorsi, measured by hydroxyproline analysis and histological grading of picrosirius red-stained sections, was greater in mdx ( P < 0.05). We conclude that kyphotic index is a useful measure in mdx and other kyphotic mouse strains, and assessment of paralumbar and accessory respiratory muscles enhance understanding of spinal deformity in muscular dystrophy.
Voltage-Gated Calcium Channels Mediate Intracellular Calcium Increase inWeaverDopaminergic Neurons During Stimulation of D2and GABABReceptors
Authors: Guatteo Ezia , Bengtson C. Peter , Bernardi Giorgio , Mercuri Nicola B.
Published: July 2004

The weaver ( wv) mutation affects the pore-forming region of the inwardly rectifying potassium channel (GIRK) leading to degeneration of cerebellar granule and midbrain dopaminergic neurons. The mutated channel ( wvGIRK) loses its potassium selectivity, allowing sodium (Na+) and possibly calcium ions (Ca2+) to enter the cell. Here we performed whole cell patch-clamp recordings combined with microfluorometry to investigate possible differences in calcium ([Ca2+]i) dynamics in native dopaminergic neurons (expressing the wvGIRK2 subunits) in the midbrain slice preparation from homozygous weaver ( wv/wv) and control (+/+) mice. Under resting conditions, [Ca2+]iwas similar in wv/wv compared with +/+ neurons. Activation of wvGIRK2 channels by D2and GABABreceptors increased [Ca2+]iin wv/wv neurons, whereas activation of wild-type channels decreased [Ca2+]iin +/+ neurons. The calcium rise in wv/wv neurons was abolished by antagonists of the voltage-gated calcium channels (VGCC); voltage clamp of the neuron at −60 mV; and hyperpolarization of the neuron to −80 mV or more, in current clamp, and was unaffected by TTX. Therefore we propose that wvGIRK2 channels in native dopamine neurons are not permeable to Ca2+, and when activated by D2and GABABreceptors they mediate membrane depolarization and an indirect Ca2+influx through VGCC rather than via wvGIRK2 channels. Such calcium influx may be the trigger for calcium-mediated excitotoxicity, responsible for selective neuronal death in weaver mice.
Hereditary Vascular Anomalies
Authors: Tille J.-C. , Pepper M.S.
Published: July 2004

Increased understanding of the mechanisms of angiogenesis and lymphangiogenesis has provided a glimpse at some of the molecules involved in the pathophysiology of hemangiomas and vascular malformations. This review focuses on recent advances in our understanding of the mechanisms of angiogenesis/lymphangiogenesis and the differentiation of arterial, venous, and lymphatic vessels. We integrate this knowledge with new data obtained from genetic studies in humans, which have revealed a number of heretofore-unsuspected candidates involved in the development of familial vascular anomalies. We present a common infantile vascular tumor, hemangioma, and then focus on hereditary familial vascular and lymphatic malformations. We also summarize transgenic mouse models for some of these malformations. It seems reasonable to believe that novel therapeutic strategies will soon emerge for the treatment of hemangiomas and vascular malformations.
Principal Role of Glycoprotein VI in α2β1 and αIIbβ3 Activation During Collagen-Induced Thrombus Formation
Authors: Lecut Christelle , Schoolmeester Anne , Kuijpers Marijke J.E. , Broers Jos L.V. , van Zandvoort Marc A.M.J. , Vanhoorelbeke Karen , Deckmyn Hans , Jandrot-Perrus Martine , Heemskerk Johan W.M.
Published: July 2004

Objective—

High-shear perfusion of blood over collagen results in rapid platelet adhesion, aggregation, and procoagulant activity. We studied regulation of α2β1 and αIIbβ3 integrin activation during thrombus formation on collagen.

Methods and Results—

Blockade of glycoprotein (GP) VI by 9O12 antibody or of P2Y purinergic receptors permitted platelet adhesion but reduced aggregate formation, fibrinogen binding, and activation of α2β1 and αIIbβ3, as detected with antibodies IAC-1 and PAC1 directed against activation-dependent epitopes of these integrins. Combined blockade of GPVI and P2Y receptors and thromboxane formation abolished integrin activation but still allowed adhesion of morphologically unstimulated, nonprocoagulant platelets. Exogenous ADP partly restored the suppressive effect of GPVI blockade on integrin α2β1 and αIIbβ3 activation. Adhesion was fully inhibited only with simultaneous blocking of GPVI and α2β1, indicating that the integrin can support platelet–collagen binding in the absence of its activation. Blockade or absence of GPIbα only moderately influenced integrin activation and adhesion unless GPVI was inhibited.

Conclusions—

GPVI- and autocrine-released ADP induce affinity changes of α2β1 and αIIbβ3 during thrombus formation on collagen under flow. These integrin changes are dispensable for adhesion but strengthen platelet–collagen interactions and thereby collagen-induced platelet activation.
Estrogen Replacement Treatment in Diabetic Ovariectomized Female Rats Potentiates Postischemic Leukocyte Adhesion in Cerebral Venules
Authors: Xu Hao-Liang , Baughman Verna L. , Pelligrino Dale A.
Published: July 2004

Background and Purpose—

Chronic 17β-estradiol (E
2
) replacement therapy in ovariectomized (OVX) female rats reduces leukocyte adhesion and brain damage after transient forebrain ischemia. Recently, we found that E
2
treatment in diabetic OVX females was associated with enhanced postischemic neuropathology. We tested the hypothesis that in chronically hyperglycemic diabetic OVX females, chronic E
2
replacement potentiates post-transient forebrain ischemia leukocyte adhesion.

Methods—

Pial venules were observed through closed cranial windows. Adherence of rhodamine 6G–tagged leukocytes was monitored before and 10 hours after transient forebrain ischemia (20 minutes right common carotid artery occlusion plus hemorrhagic hypotension) in intact, untreated OVX and E
2
-treated OVX females rendered diabetic via streptozotocin. Leukocyte adhesion was quantitated as the percentage venular area occupied by adherent leukocytes.

Results—

At 2 hours after transient forebrain ischemia, a similar low level of leukocyte adhesion was seen in the 3 groups (<3% of the venular area). Starting at ≈4 hours after ischemia, leukocyte adhesion in the E
2
-treated OVX females rose to significantly higher levels compared with the other groups. Relative to the 2-hour value, the level of adhesion at 10 hours was 12.5-fold, 4-fold, and 5-fold greater in the E
2
-treated OVX, OVX, and intact groups, respectively. Leukocyte extravasation (beginning after 6 hours of reperfusion) was observed in a majority (64%) of the E
2
-treated animals, with limited or no extravasation seen in the intact or OVX groups.

Conclusions—

These results suggest that factors associated with diabetes and chronic hyperglycemia convert E
2
from a counterinflammatory to a proinflammatory substance in an ischemic setting.
Charlson Index Comorbidity Adjustment for Ischemic Stroke Outcome Studies
Authors: Goldstein Larry B. , Samsa Gregory P. , Matchar David B. , Horner Ronnie D.
Published: July 2004

Background and Purpose—

The Charlson Index is commonly used in outcome studies to adjust for patient comorbid conditions, but has not been specifically validated for use in studies of ischemic stroke. The purpose of the present study was to determine whether outcomes of ischemic stroke patients varied on the basis of the Charlson Index.

Methods—

The Department of Veterans Affairs (VA) Stroke Study prospectively identified stroke patients admitted to 9 VA hospitals between April 1995 and March 1997. The Charlson Index was scored on the basis of discharge
International Classification of Diseases, 9th Revision, Clinical Modification
coding and dichotomized (low comorbidity 0 or 1 versus high ≥2) for analysis. Validity was assessed on the basis of modified Rankin score at hospital discharge (good outcome 0 or 1 versus poor ≥2 or dead) and 1-year mortality, adjusting for initial stroke severity.

Results—

Of the 960 enrolled ischemic stroke patients, 23% had a Charlson Index of 0, 34% 1, 22% 2, 12% 3, and 8% ≥4. Forty-eight percent of those with a low Charlson Index had a good outcome at discharge versus 37% of those with a high Charlson Index (
P
<0.001). For 1-year mortality, the proportions were 16% versus 26%, respectively (
P
<0.001). Logistic regression adjusting for initial stroke severity showed that those with a high Charlson Index had 36% increased odds of having a poor outcome at discharge (
P
=0.038) and 72% greater odds of death at 1 year (
P
=0.001). Every 1-point increase in Charlson Index was independently associated with a 15% increase in the odds of a poor outcome at discharge (
P
<0.005) and a 29% increase in the odds of death by 1 year (
P
<0.001).

Conclusions—

These data support the validity of the Charlson Index as a measure of comorbidity for use in ischemic stroke outcome studies.
Pro-CAS
Authors: Theiss Wolfram , Hermanek Peter , Mathias Klaus , Ahmadi Ramazanali , Heuser Lothar , Hoffmann Franz-Josef , Kerner Rüdiger , Leisch Franz , Sievert Horst , von Sommoggy Stefan
Published: July 2004

Background and Purpose—

The German Societies of Angiology and Radiology have instituted a prospective registry of carotid angioplasty and stenting (CAS) to limit uncontrolled use of CAS and to collect data about technique and results of CAS outside clinical trials.

Methods—

A total of 38 centers register their patients prospectively before CAS is performed. At discharge, technical details, periprocedural medication, and the clinical course are reported on a standardized form.

Results—

During the first 48 months, 3853 planned interventions were recorded, and CAS was actually attempted on 3267 patients of whom 1827 (56%) were symptomatic and 1433 (44%) were asymptomatic. In 3127 (98%) cases, stents were used, of which 2784 (89%) were of the self-expanding type. Other technical aspects such as the use of guiding catheters and protection devices varied widely among the centers. Periprocedural medication rather uniformly included aspirin and clopidogrel before and after CAS and high-dose heparin and atropin during CAS. CAS was successful in 3207 (98%) cases. There was a 0.6% (n=18) mortality rate, a 1.2% (n=38) major stroke rate, and a 1.3% (n=41) minor stroke rate. The combined stroke and death rate was 2.8% (n=90).

Conclusions—

These prospective multicenter data are likely to give a realistic picture of the possibilities and limitations of CAS in the general community. They suggest that CAS may be performed with similar results in the general community as they have been reported by highly specialized centers and in clinical studies.
Antibodies to Periodontal Pathogens and Stroke Risk
Authors: Pussinen Pirkko J. , Alfthan Georg , Rissanen Harri , Reunanen Antti , Asikainen Sirkka , Knekt Paul
Published: July 2004

Background and Purpose—

The association between cerebrovascular events and periodontitis has been found in few studies based on clinical periodontal examinations. However, evidence on the association between periodontal pathogens and stroke is lacking. Therefore, the aim of the study was to investigate whether elevated levels of serum antibodies to major periodontal pathogens predict stroke in a case–control study.

Methods—

The study population comprised 6950 subjects (aged 45 to 64 years) who participated in the Mobile Clinic Health Survey in 1973 to 1976 in Finland. During a follow-up of 13 years, a total of 173 subjects had a stroke. From these, 64 subjects had already experienced a stroke or had signs of coronary heart disease (CHD) at baseline, whereas 109 subjects were apparently healthy. Two controls per case were matched for age, gender, municipality, and disease status. Serum IgG and IgA class antibody levels to the periodontal pathogens,
Actinobacillus actinomycetemcomitans
and
Porphyromonas gingivalis
, were determined by multiserotype enzyme-linked immunosorbent assay.

Results—

The cases identified during the follow-up that were free of stroke or CHD at baseline were more often IgA-seropositive for
A. actinomycetemcomitans
than were their controls, 41.3% versus 29.3%. Compared with the seronegative, the seropositive subjects had a multivariate odds ratio of 1.6 (95% CI, 1.0 to 2.6) for stroke. The patients with a history of stroke or CHD at baseline were more often IgA-seropositive for
P. gingivalis
than were their controls, 79.7% versus 70.2%. When compared with the seronegative, the seropositive subjects had an odds ratio of 2.6 (1.0 to 7.0) for secondary stroke.

Conclusions—

The present prospective study provides serological evidence that an infection caused by major periodontal pathogens is associated with future stroke.
National Cultural Differences in the Use and Perception of Internet-based NSS: Does High or Low Context Matter?
Authors: Kersten Gregory , Vetschera Rudolf , Koeszegi Sabine
Published: July 2004

In this article, we apply an extended technology acceptance model (TAM) to explore whether national culture influences a user's perception and use of Internet-based negotiation support systems (NSS). In particular, we are interested in whether different preferences for communication patterns, as we find them for low-context and high-context cultures, influence the use and perception of different NSS support tools. The Web-based system Inspire, which provided data for our analysis has been used by over 2000 entities worldwide in experimental negotiations. Our results show that, based on the need to establish a social context in computermediated negotiations, users from high-context cultures exchange significantly more messages and offers during negotiations than users from low-context cultures. Analytical negotiation support is valued significantly higher by users from low-context cultures than by users from highcontext cultures as this problem-solving approach is more compatible with their preference for direct and task-oriented communication.
Similarities and Differences in Role Conflict, Role Commitment, and Job Satisfaction for Female and Male High School Principals
Authors: Eckman Ellen Wexler
Published: July 2004

The purpose of this study was to determine the effect of gender, role conflict, role commitment, and job satisfaction on the high school principal. Data were collected from high school principals in three midwestern states. The results indicated that there are differences between female and male high school principals in their personal and professional attributes as well as in role conflict. There were similarities between female and male high school principals in terms of role commitment and job satisfaction.
Incentives for Charter Schools: Building School Capacity Through Cross-Sectoral Alliances
Authors: Wohlstetter Priscilla , Malloy Courtney L. , Smith Joanna , Hentschke Guilbert
Published: July 2004

In this exploratory study, the authors examine the recent emergence of cross-sectoral alliances—organizations voluntarily working together to solve issues of mutual concern—in kindergarten through 12th-grade education. The article utilizes an economic approach to interagency collaboration and focuses on alliances in charter schools. The authors seek to (a) analyze the extent to which charter school legislation encourages or discourages alliances, (b) examine the types of organizations that form alliances with charter schools and the range of contributions they provide, and (c) assess the various incentives that lead charter schools and other organizations to form alliances. Implications of the findings for educational practice and policy as well as future research are discussed.
Teacher Involvement in School Development Activity and its Relationships to Attitudes and Subjective Norms among Teachers: a Study of Norwegian Elementary and Junior High School Teachers
Authors: Midthassel Unni Vere
Published: July 2004

This article is based on a survey covering 1,435 Norwegian teachers in compulsory schools in 47 municipalities. It examines associations between teacher involvement in school development activity (SDA) and teachers’ attitudes toward SDA as well as their perceived working environment concerning innovation activity among staff and the principal’s involvement in SDA. Results showed that teachers’ perception of SDA as a relevant task was the strongest predictor of the variables examined. Furthermore, teacher perception of the innovation culture among staff and of a principal’s involvement moderately accounted for teacher involvement in SDA. Results suggest that the relevance of SDA has a stronger effect on teacher involvement in SDA if the innovation culture is perceived to be positive and the principal is seen to be involved in SDA. Finally, the results indicated no significant differences between elementary and junior high school teachers with regard to the predictors for teacher involvement in SDA.
A Note on How to Quantify and Report Whether Irt Parameter Invariance Holds: When Pearson Correlations are Not Enough
Authors: Rupp André A. , Zumbo Bruno D.
Published: July 2004

Based on seminal work by Lord and Hambleton, Swaminathan, and Rogers, this article is an analytical, graphical, and conceptual reminder that item response theory (IRT) parameter invariance only holds for perfect model fit in multiple populations or across multiple conditions and is thus an ideal state. In practice, one attempts to quantify the degree to which a lack of invariance is likely to be present through repeated calibrations of item and examinee parameters. Motivated by two recent studies on item parameter invariance, this article shows how a seemingly intuitive measure such as Pearson’s Product-Moment Correlation Coefficient (PPMCC) is insufficient for that purpose, as it is not sensitive to restrictive linear relationships such as identities, which are required for parameter invariance to hold. It thus misses, for example, additive group-level effects, which are observed in practice with translated instruments or with large-scale assessments such as TIMSS.
Universal Nonverbal Intelligence Test Factor Invariance Across Deaf and Standardization Samples
Authors: Maller Susan J. , French Brian F.
Published: July 2004

The Universal Nonverbal Intelligence Test (UNIT) is an individually administered, nonverbal intelligence test designed for use with non-English-speaking, limited English proficient, or deaf children. The aim of this study was to assess the factor structure invariance of the UNIT across deaf and standardization samples through the use of multisample confirmatory factor an alysis. Two theoretical models were evaluated: a primary two-factor (Memory and Reasoning) model and a secondary two-factor (Symbolic and Nonsymbolic) model. The general forms of both models were invariant across groups, thus supporting both theoretical models. For the primary model, partial measurement invariance was found. A follow-up analysis found that the analogic reasoning measurement intercept was not invariant, indicating that the expected subtest scores for deaf examinees were lower than those for examinees in the standardization sample. In addition, the standardization sample had a higher Memory latent factor mean than the deaf sample did. The secondary model was not invariant, with three pattern coefficients differing across groups.
Psychometric Analyses of the Adult Manifest Anxiety Scale–Adult Version among Young and Middle-Aged Adults
Authors: Lowe Patricia A. , Reynolds Cecil R.
Published: July 2004

Responses of 871 adults to the Adult Manifest Anxiety Scale–Adult version (AMAS-A) were factor analyzed using the method of principal axis factoring with promax rotation. Factor analysis yielded a four-factor solution: three anxiety factors (Worry/Oversensitivity, Stress, and Physiological Anxiety) and a Lie factor. The AMAS-A’s three factor structure of anxiety is consistent with multidimensional theories of anxiety and lends support to the validity of the interpretation of the AMAS-A scores as reflecting anxiety in several dimensions. Temporal stability and convergent and discriminant validity of the AMAS-A test scores were also examined in a sample of 76 young and middleaged adults. Results indicated good to excellent test-retest reliability for the AMAS-A scores over a 2- to 3-week interval. Evidence for convergent and discriminant validity of the AMAS-Ascores as measures of various aspects of anxietywas found. Implications of the findings are discussed.
SSAIS: a Program to Assess Adverse Impact in Multistage Selection Decisions
Authors: De Corte Wilfried
Published: July 2004

The article describes a Windows program to estimate the expected value and sampling distribution function of the adverse impact ratio for general multistage selections. The results of the program can also be used to predict the risk that a future selection decision will result in an outcome that reflects the presence of adverse impact. The method therefore provides the selection practitioner with a valuable tool to screen intended selection scenarios in terms of their potential to address the adverse impact problem.
An Analytical Study of Cavitation in Rubber-Toughened Polymers
Authors: Wang Qi-Zhi , Lee Dong-Joo
Published: July 2004

An analysis is presented to study the cavitation of rubber particles, and its influence on the mechanical properties of rubber-toughened polymers. This analysis is developed from our previous analytical method using a quasi-sphere model to determine the mechanical properties of rubber-toughened polymers without a cavity. The behaviour of the rubber particle is described by Ogden's formulation and large deformation theory is used to explain the behaviour. Both initiation and elastic deformation of the cavity are considered. The method is simple and the formulas (including the cavitation criterion) are explained so that they can be used easily. It has been found that even a small defect in a rubber sphere has a significant influence on the bulk modulus of the rubber sphere and the properties of the composite material.
Joining Forces in Assembled Composite Beams
Authors: Liu Dahsin , Shakour Elias , Lu Xianqiang
Published: July 2004

This study investigated the joining force of assembled composite beams. Two identical composite laminates made of cross-ply glass/epoxy were joined via various joining techniques such as adhesive bonding, mechanical riveting, stitching joining and combinations of these techniques. The assembled two-laminate composite beams were loaded by four-point bending. The corresponding normal strains were identified by moire interferometry. Depending on the joining condition between the laminates, the moire patterns of u-fringes and v-fringes may be continuous or discontinuous across the joining interface. To quantify the joining condition, two analytical models based on the Classical Beam Theory, the interface model and the interphase model, were presented. The joining forces of the assembled composite beams were identified. Mechanical riveting was found to be an efficient joining technique for assembling the thin composite laminates.
Improvement of Interfaces by Tethered Polymer Chains. Part II: Evaluation of a Particulate Composite at Very High Strain Rate
Authors: Greenfield M. J. , Hunter T. F. , Kalika D. S. , Penn L. S.
Published: July 2004

A study of the effect of tethered chains at the fiber-matrix interface on the performance of a particulate composite at very high strain rate was conducted. The materials system studied was composed of glass beads, polysulfone matrix, and polysulfone tethered chains. The entanglement of the tethered chains with the matrix in the composite specimen was confirmed by physico-chemical analysis. Although the tethered chains had been shown to have a beneficial effect on the interface in a single-fiber, model composite, they were found to have no effect whatsoever on the macroscopic behavior of the particulate composite at very high strain rate (150/s).
Dimensional Accuracy of Thermoset Composites: Simulation of Process-Induced Residual Stresses
Authors: Zhu Qi , Geubelle Philippe H. , Li Min , Tucker Charles L.
Published: July 2004

The warpage of thermoset composite structures during the manufacturing process is a direct consequence of residual stress development. The capability to predict residual stresses is crucial to the manufacture of dimensionally accurate composite structures. This paper is focused on understanding the fundamental issues leading to residual stresses in thermoset polymer composites and their effect on the dimensional accuracy of the manufactured components. Unlike most existing work, which use simplified geometrical and/or material models or focused merely on the cooldown process, a three dimensional coupled thermo-chemo-viscoelastic model is developed to simulate the heat transfer, curing, residual stresses and deformation of a composite part during the entire cure cycle. The predicted values of curvature for cross-ply graphite-epoxy laminates agree well with experimental observations. The numerical result indicates that a significant fraction of the residual stress develops before cooldown. Detailed studies are also performed to examine the springforward phenomenon in L-shaped composite parts. The finite element results showthat mold design (male vs. female mold), mold thermal expansion, part thickness, and fiber orientation all play an important role on the final shape of the parts, while cure cycle parameters such as dwell temperature, pressure, and cooling rate have less effect on springforward.
An Investigation of the Structure-Property Relationship of Knitted Composites
Authors: Khondker O. A. , Herszberg I. , Leong K. H.
Published: July 2004

The tensile and compressive behaviours of knitted composites in the wale and course directions were studied for their dependence upon knit architecture and varying knit/structural parameters, such as loop length and stitch density. Strength, modulus and strain-to-failure were investigated. In addition, Poisson’s ratio of the composites under tensile loading was also studied. Post-failure examination was carried out on the test specimens using stereo-optical and scanning electron microscopy to analyse their fracture mechanisms. It has been found that any change in the mechanical properties of the knitted composites with respect to architecture and knit/structural parameters are broadly related to accompanying modifications to the state of the microstructural imperfections, viz. fibre bending and fibre crossover junctions, and also to the relative fibre distribution along the two principal loading axes, in the knit structure.
Fiber Orientation Effects on High Strain Rate Properties of Graphite/Epoxy Composites
Authors: Vinson Jack R. , Woldesenbet Eyassu
Published: July 2004

Excellent mechanical properties such as high-strength, low weight, fatigue life, and impact resistance, as well as advanced manufacturing methods and flexibility of the stacking sequence make polymer matrix composites attractive candidates for use in several performance-oriented structures. However, relatively little is known of their response to impact loading, which usually occurs at strain rates higher than those used to measure the quasi-static mechanical properties of materials. In this study, the split-Hopkinson bar is used extensively to study the effect of fiber orientation on the compressive dynamic properties of a unidirectional IM7/8551-7 graphite/epoxy composite. The specimens were approximately 3/8. cubes, and were prepared using a water-cooled diamond grit blade. The off-axis angles were 0 (longitudinal direction), 15, 30, 45, 60, 75, and 90 (transverse direction) degrees. Quasi-static tests were also performed for comparison purposes. The high strain rates vary from 250-1100/s. The tests show that changing the fiber orientation changes the values of the ultimate strength and strain of the IM7/8551-7 graphite/epoxy composite. The results show that the ultimate strength in general decreases as the off-axis (test) angle is increased. However, the results show that the decrease is not uniform as in the case of the quasi-static tests. The strain increases for initial increase in the off-axis angle, but then the results don’t show any consistent trend for additional angle increments. A semi-empirical equation is obtained for this material system and can be modified to account for other polymer matrix composites.
High Strain-Rate Behavior of Plain-Weave S-2 Glass/Vinyl Ester Composites
Authors: Gama Bazle A. , Gillespie John W. , Mahfuz Hassan , Raines Roshan P. , Haque Anwarul , Jeelani Shaik , Bogetti Travis A. , Fink Bruce K.
Published: July 2004

Thick-section composites made from plain-weave S-2 glass fabric (24 oz./sq. yard) and vinyl ester (411-C50) resin have been tested over a wide range of strain-rates (200-1600 s -1) using a compression split Hopkinson pressure bar (SHPB) with a momentum trapping device. Experiments were performed in two material directions: thickness and fill. Three different types of specimens having rectangular cross sections were tested with thickness ranging from 3.8 mm to 12.7 mm. The strain-rate effects on maximum stresses and maximum non-linear strains have been characterized. The dominant failure modes of the material have been determined through optical and scanning electron microscopy (OM and SEM). It has been identified that the dynamic ultimate stress and failure strain is higher than the corresponding quasi-static values. The ultimate stress is found rate insensitive for both thickness and fill direction loading. The non-linear failure strain is also found to be rate insensitive in the case of thickness direction loading; however, the failure strain increases with strain-rate in the case of fill direction loading. The dominant dynamic failure modes in thickness direction loading are compressive matrix cracking, fiber breakage, and lateral flow of fiber bundles. In the fill direction loading, the dynamic failure modes are kink band formation, delamination, transverse matrix cracking, and longitudinal splitting.
Studies on the Influence of Through-the-Thickness Reinforcement on Low-Velocity and High Strain Rate Response of Woven S2-Glass/Vinyl Ester Composite
Authors: Hosur Mahesh V. , Abraham A. , Jeelani S. , Vaidya U. K.
Published: July 2004

Due to their inherent weakness in the thickness direction, laminated fiber reinforced composites are susceptible to undergo large delamination damage as well as splitting when subjected to transverse loading and microbuckling under in-plane compressive loading. In the current work, an effort is made to improve the transverse strength by providing discrete 3D reinforcement in the form of pins and stitching the laminate in the thickness direction. The effectiveness of the 3D reinforcement is compared with 2D-Plain laminates. The laminates were made of 15 layers of 2 × 2 twill weave S2-glass fabric and vinyl ester C-50 resin system. Specimens of size 75 × 100mmwere subjected to low-velocity impact loading at energy levels of 20, 30 and 40 joules. The effectiveness of 3D-reinforcement to in-plane dynamic loading was studied using a Compression Split Hopkinson’s Pressure Bar at three different strain rates of 327/s, 436/s and 544/s using cubic samples of size 6.0mm. The stitched samples were subjected to high strain rate loading in two configurations. In the first, the sample (referred to as 3D-Stitch1) had stitching along the loading direction at the center while in the second; the sample (referred to as 3D-Stitch2) had an additional stitch line along the width at the center. The results of the study indicate that, reinforcement using stitching confines the delamination growth under low-velocity impact loading. Reinforcement in the form of pins did not show considerable improvement in the damage containment. However, under high strain rate compressive loading, 3D-Stitch1 and 3D-Pin reinforced laminates demonstrated higher compressive strengths at the strain rates of 327/s and 436/s. Stitch2 and 2D-Plain samples, in comparison, exhibited lower strength. Both 2D-Plain and 3D-Pin reinforced laminates exhibited increasing strength with the increase in the strain rate. Whereas, stitched laminates exhibited increase in strength from the strain rate of 327/s to 436/s before dropping in magnitude at 544/s. Thiswas attributed to the localized damage in the fabric due to piercing of the needle during stitching resulting in resin pooling.
Identifying Subtypes of Civil Psychiatric Patients at High Risk for Violence
Authors: Skeem Jennifer L. , Mulvey Edward P. , Appelbaum Paul , Banks Steven , Grisso Thomas , Silver Eric , Robbins Pamela Clark
Published: July 2004

Advances in risk assessment have improved the ability to identify psychiatric patients at high risk for violence. Identifying these patients is necessary for developing treatment to address their needs. However, if violence is caused by risk factors that vary across patients, relatively homogeneous subgroups of high-risk patients must be identified and studied to develop effective risk management programs for each. This study was designed to identify and describe valid subtypes of patients reliably identified as at high risk by the multiple Iterative Classification Tree (ICT) risk assessment approach. After existing typologies of violent individuals were integrated to develop hypothesized subtypes of high-risk patients, data on 165 patients identified as at high risk by the multiple ICT were used to determine whether clinically meaningful subtypes could be identified and externally validated. Three groups (alpha, beta, and delta) largely consistent with the hypothesized subtypes and their correlates were identified. The implications of these findings for research and treatment development efforts are discussed.
An Empirical Test of Holmes and Holmes’s Serial Murder Typology
Authors: Canter David V. , Wentink Natalia
Published: July 2004

This article presents the results of an empirical test of Holmes and Holmes’s serial murder classification scheme. Crime scene evidence from 100 U.S. serial murders, each the third in a distinct series, was content analyzed. The co-occurrence of content categories derived from the crime scene material was submitted to smallest space analysis. The features characteristic of the category of “power or control” killings were found to be typical of the sample as a whole, occurring in more than 50% of cases, and thus did not form a distinct type. Limited support was found for aspects of the lust, thrill, and mission styles of killing, but this support drew attention to differences in the ways victims were dealt with, through mutilation, restraints, or ransacking their property rather than the motivations implicitly inferred in Holmes and Holmes’s typology. The current results are presented as an empirical basis for the classification of serial killings on which more detailed models can be built.
The Psychology of Black Women: Studying Women’s Lives in Context
Authors: Thomas Veronica G.
Published: July 2004

This article provides a critical analysis of a distinctive psychology of Black women, discusses the relevant epistemologies and conceptual framework that can inform such a perspective, and suggests a set of guiding principles for advancing theory and research on Black women within a historically and contextually relevant framework. A discussion of who is best suited to study the lives of Black women is also provided. The article concludes with a charge for a psychology of Black women that will examine previously ignored issues, formulate and test of new (and old) hypotheses, and develop alternative theoretical paradigms that are sensitive to the realities and contextualized lives of this population.
A Postscript for Research on Black Women: New Populations, New Directions
Authors: Reid Pamela Trotman
Published: July 2004

This postscript challenges researchers to address the fundamental question, how do we define Black women? Changes in various aspects of Blackness—the Black family, the Black community, the Black experience—are highlighted. Taking into consideration these changes, clarification of how the intersection of gender and ethnicity together with other markers of status operate in the lives of Black women is stressed.
Toward the Development of the Stereotypic Roles for Black Women Scale
Authors: Thomas Anita Jones , Witherspoon Karen McCurtis , Speight Suzette L.
Published: July 2004

Preliminary findings on the validation of the Stereotypic Roles for Black Women Scale (SRBWS) are presented. A sample of 186 African American women took the SRBWS along with the Rosenberg Self-Esteem Scale and the Racial Identity Attitude Scale–B. A confirmatory factor analysis supported a four-factor structure of the scale, and moderate reliability estimates were found for each of the interrelated but distinct subscales. Stepwise regression analyses revealed that Mammy and Sapphire images were significant predictors of self-esteem scores and that the internalized stereotypic roles contributed unique variance over racial identity attitudes in understanding self-esteem in Black women. Suggestions for future research and validation of the SRBWS are discussed.
Obesity among Black Adolescent Girls: Genetic, Psychosocial, and Cultural Influences
Authors: Alleyne Sylvan I. , LaPoint Velma
Published: July 2004

This article focuses on the causes, consequences, and prevention of obesity among a subgroup of the American population, Black adolescent girls. Using an ecological perspective on obesity among Black adolescent girls, including feminist-womanist perspectives and historical and medical sociological perspectives, the authors discuss genetic, psychosocial, and cultural factors that may influence the propensity of Black adolescent girls’ susceptibility to obesity and to diabetes, one of the major complications of obesity. Prevention strategies, including individual and structural interventions, are illuminated.