bluuebunny/crossref_metadata_2025 huggingface dataset:
Sex Differences in Mechanisms and Outcome of Neonatal Hypoxia-Ischemia in Rodent Models: Implications for Sex-Specific Neuroprotection in Clinical Neonatal Practice
Authors: Hill Courtney A. , Fitch R. Holly
Published: February 2012

Clinical findings show that male infants with hypoxic-ischemic injury (HI) fare more poorly than matched females on cognitive outcomes. Rodent models of neonatal hypoxia-ischemia support this difference, with data showing that perinatal brain injury leads to long-term behavioral deficits primarily in male rodents and in female rodents treated with early androgens. Results support the idea that sex-specific gonadal hormones may modulate developmental response to injury and dovetail with overwhelming evidence of developmental androgen effects on typical brain morphology and behavior. However, mechanisms underlying sex differences in response to early brain injury may be more complicated. Specifically, activation of cell death pathways in response to HI may also differ by sex. In females, the preferential activation of the caspase-dependent apoptotic pathway may actually afford greater protection, potentially due to the actions of X-linked inhibitor of apoptosis (XIAP) within this pathway. This contrasts the pattern of preferential activation of the caspase-independent pathway in males. While an integrated model of sex-specific hormonal and genetic modulation of response to early injury remains to be fully elucidated, these findings suggest that infants might benefit from sex-specific neuroprotection following HI injury.
A Unifying Hypothesis for Familial and Sporadic Alzheimer's Disease
Authors: Proctor Carole J. , Gray Douglas A.
Published: February 2012

Alzheimer's disease (AD) is characterised by the aggregation of two quite different proteins, namely, amyloid-beta (Aβ), which forms extracellular plaques, and tau, the main component of cytoplasmic neurofibrillary tangles. The amyloid hypothesis proposes that Aβplaques precede tangle formation but there is still much controversy concerning the order of events and the linkage between Aβand tau alterations is still unknown. Mathematical modelling has become an essential tool for generating and evaluating hypotheses involving complex systems. We have therefore used this approach to discover the most probable pathway linking Aβand tau. The model supports a complex pathway linking Aβand tau via GSK3β, p53, and oxidative stress. Importantly, the pathway contains a cycle with multiple points of entry. It is this property of the pathway which enables the model to be consistent with both the amyloid hypothesis for familial AD and a more complex pathway for sporadic forms.
Incidence of Tissue Coring During Transseptal Catheterization When Using Electrocautery and a Standard Transseptal Needle
Authors: Greenstein Eugene , Passman Rod , Lin Albert C. , Knight Bradley P.
Published: February 2012

Background—

The application of radiofrequency electrocautery to a standard, open-ended transseptal needle has been used to facilitate transseptal puncture (TSP). The purpose of this study was to determine the incidence of cardiac tissue coring when this technique is used.

Methods and Results—

A model using excised swine hearts submerged in a saline-filled basin was developed to simulate TSP with electrocautery and a standard transseptal needle. Punctures were performed without the use of electrocautery and by delivering radiofrequency energy to the transseptal needle using a standard electrocautery pen at 3 target sites (fossa ovalis, non–fossa ovalis septum, and aorta). The tissue of the submerged heart was gently tented, and the needle was advanced on delivery of radiofrequency. The devices were retracted, and the needle was flushed in a collection basin. None of the TSPs without cautery caused tissue coring. For TSPs using electrocautery, the frequency of coring was at least 21% for any puncture permutation used in the study and averaged 37% at septal sites (
P
<0.001 compared with punctures without cautery). Tissue coring occurred in 33 of 96 (35%) punctures through the fossa ovalis and in 38 of 96 (40%) punctures through non–fossa ovalis septum. The frequency of tissue coring at aortic sites was 62 of 96 (65%), which was significantly higher than at the septal sites (
P
<0.001).

Conclusions—

In an animal preparation, TSP at the level of the fossa ovalis using electrocautery and a standard open-ended Brockenbrough needle resulted in coring of the septal tissue in 35% of cases (33 of 96 punctures).
Processing of Emotional Distraction Is Both Automatic and Modulated by Attention: Evidence from an Event-related fMRI Investigation
Authors: Shafer Andrea T. , Matveychuk Dmitriy , Penney Todd , O'Hare Aminda J. , Stokes Jared , Dolcos Florin
Published: February 2012

Traditionally, emotional stimuli have been thought to be automatically processed via a bottom–up automatic “capture of attention” mechanism. Recently, this view has been challenged by evidence that emotion processing depends on the availability of attentional resources. Although these two views are not mutually exclusive, direct evidence reconciling them is lacking. One limitation of previous investigations supporting the traditional or competing views is that they have not systematically investigated the impact of emotional charge of task-irrelevant distraction in conjunction with manipulations of attentional demands. Using event-related fMRI, we investigated the nature of emotion–cognition interactions in a perceptual discrimination task with emotional distraction by manipulating both the emotional charge of the distracting information and the demands of the main task. Our findings show that emotion processing is both automatic and modulated by attention, but emotion and attention were only found to interact when finer assessments of emotional charge (comparison of most vs. least emotional conditions) were considered along with an effective manipulation of processing load (high vs. low). The study also identified brain regions reflecting the detrimental impact of emotional distraction on performance as well as regions involved in coping with such distraction. Activity in the dorsomedial pFC and ventrolateral pFC was linked to a detrimental impact of emotional distraction, whereas the dorsal ACC and lateral occipital cortex were involved in helping with emotional distraction. These findings demonstrate that task-irrelevant emotion processing is subjective to both the emotional content of distraction and the level of attentional demand.
Tropical and Subtropical Meridional Latent Heat Transports by Disturbances to the Zonal Mean and Their Role in the General Circulation
Authors: Shaw Tiffany A. , Pauluis Olivier
Published: February 2012

The spectrum of meridional latent heat transport in the tropics and subtropics by disturbances to the zonal mean during all seasons is analyzed. The transport is divided into stationary and transient planetary- and subplanetary-scale eddy contributions.

The stationary transport is largest in the subtropical lower troposphere and dominates the overall transport during summer. It is of planetary scale and the zonal scale of the transport corresponds to the number of subtropical anticyclones. The transient transport is large from the surface up to the midtroposphere and from the tropics to subpolar latitudes. It is dominated by the subplanetary-scale contribution during all seasons. Westward (eastward)- propagating waves dominate the transport in the tropics (subtropics and midlatitudes). The analysis reveals that, while the total eddy meridional latent heat transport is seamless from the deep tropics to the pole, it represents the sum of transport by distinct dynamical features.

The role of the eddy meridional latent heat transport in the moist isentropic circulation is assessed using the statistical transformed Eulerian mean formulation, which converts the eddy transports into streamfunctions. The addition of the eddy latent heat streamfunction to the Eulerian mean plus eddy sensible heat streamfunction increases the mass transport by a factor of 2–3 in the subtropics and midlatitudes. The eddy transport is found to dominate the transport across the subtropical boundary. During Northern Hemisphere summer there is virtually no circulation in the absence of eddy latent heat transport. The results highlight the important role of latent heat transport by subtropical anticyclones and tropical and baroclinic waves in the general circulation.
Writing Mixed Research Reports
Authors: Leech Nancy L.
Published: February 2012

For many researchers, writing the research report is among the most difficult steps. When writing about a mixed methods research study, researchers have had little guidance for how to structure the manuscript. Thus, the purpose of this article is to present multiple approaches to reporting information from a mixed research study. Recommendations for mixed research writing from the extant literature are delineated, and 12 themes that were identified across these texts are presented. The multitude of approaches and organizational possibilities for the mixed research report are explored. Emphasis is placed on allowing the researcher to be creative in her or his presentation of a mixed methods research report.
Workplace Racial Discrimination and Middle Class Vulnerability
Authors: Roscigno Vincent J. , Williams Lisa M. , Byron Reginald A.
Published: February 2012

Middle-class minority workers have skill and human capital credentials which should confer protections and relative workplace power. Moreover, they often work in more bureaucratic contexts where culturally proscribed status markers, such as race, should matter little if at all. In this article, we challenge such assumptions by quantitatively and qualitatively examining several hundred cases of workplace racial discrimination and the degree of middle-class African American vulnerability. Notable are significant levels of firing discrimination for all African American workers and a heightened likelihood of mobility-based discrimination and day-to-day racial harassment for middle-class African Americans. Through qualitative case immersion, we show the core practices and processes through which these patterns manifest.
Provider Perspectives on Electronic Decision Supports for Obesity Prevention
Authors: Dryden Eileen M. , Hardin Jessica , McDonald Julia , Taveras Elsie M. , Hacker Karen
Published: February 2012

Despite the availability of national evidenced-based guidelines related to pediatric obesity screening and prevention, multiple studies have shown that primary care physicians find it difficult to adhere to them or are unfamiliar with them altogether. This article presents physicians’ perspectives on the use of electronic decision support tools, an alert and Smart Set, to accelerate the adoption of obesity-related recommendations into their practice. The authors interviewed providers using a test encounter walk-through technique that revealed a number of barriers to using electronic decision supports for obesity care in primary care settings. Providers’ suggestions for improving their use of obesity-related decision supports are presented. Careful consideration must be given to both the development of electronic decision support tools and a multilayered educational outreach strategy if providers are going to be persuaded to use such supports to help them implement pediatric obesity prevention and management best practices.
Effect of Touch Screen Button Size and Spacing on Touch Characteristics of Users With and Without Disabilities
Authors: Sesto Mary E. , Irwin Curtis B. , Chen Karen B. , Chourasia Amrish O. , Wiegmann Douglas A.
Published: February 2012

Objective: The aim of this study was to investigate the effect of button size and spacing on touch characteristics (forces, impulses, and dwell times) during a digit entry touch screen task. A secondary objective was to investigate the effect of disability on touch characteristics.

Background: Touch screens are common in public settings and workplaces. Although research has examined the effect of button size and spacing on performance, the effect on touch characteristics is unknown.

Method: A total of 52 participants ( n = 23, fine motor control disability; n = 14, gross motor control disability; n = 15, no disability) completed a digit entry task. Button sizes varied from 10 mm to 30 mm, and button spacing was 1 mm or 3 mm.

Results: Touch characteristics were significantly affected by button size. The exerted peak forces increased 17% between the largest and the smallest buttons, whereas impulses decreased 28%. Compared with the fine motor and nondisabled groups, the gross motor group had greater impulses (98% and 167%, respectively) and dwell times (60% and 129%, respectively). Peak forces were similar for all groups.

Conclusion: Button size but not spacing influenced touch characteristics during a digit entry task. The gross motor group had significantly greater dwell times and impulses than did the fine motor and nondisabled groups.

Application: Research on touch characteristics, in conjunction with that on user performance, can be used to guide human computer interface design strategies to improve accessibility of touch screen interfaces. Further research is needed to evaluate the effect of the exerted peak forces and impulses on user performance and fatigue.
Use Patterns Among Early Adopters of Adaptive Cruise Control
Authors: Xiong Huimin , Boyle Linda Ng , Moeckli Jane , Dow Benjamin R. , Brown Timothy L.
Published: February 2012

Objective:

The objective of this study was to investigate use patterns among early adopters of adaptive cruise control (ACC).

Background:

Extended use of ACC may influence a driver’s behavior in the long term, which can have unintended safety consequences.

Method:

The authors examined the use of a motion-based simulator by 24 participants (15 males and 9 females). Cluster analysis was performed on drivers’ use of ACC and was based on their gap settings, speed settings, number of warnings issued, and ACC disengaged. The data were then examined on the basis of driving performance measures and drivers’ subjective responses to trust in ACC, understanding of system operations, and driving styles. Driving performance measures included minimum time headway, adjusted minimum time to collision, and drivers’ reaction time to critical events.

Results:

Three groups of drivers were observed on the basis of risky behavior, moderately risky behavior, and conservative behavior. Drivers in the conservative group stayed farther behind the lead vehicle than did drivers in the other two groups. Risky drivers responded later to critical events and had more ACC warnings issued.

Conclusion:

Safety consequences with ACC may be more prevalent in some driver groups than others. The findings suggest that these safety implications are related to trust in automation, driving styles, understanding of system operations, and personalities.

Application:

Potential applications of this research include enhanced design for next-generation ACC systems and countermeasures to improve safe driving with ACC.
Supervisory Control of Multiple Robots
Authors: Chen Jessie Y. C. , Barnes Michael J.
Published: February 2012

Objective: A military multitasking environment was simulated to examine the effects of an intelligent agent, RoboLeader, on the performance of robotics operators.

Background: The participants’ task was to manage a team of ground robots with the assistance of RoboLeader, an intelligent agent capable of coordinating the robots and changing their routes on the basis of battlefield developments.

Method: In the first experiment, RoboLeader was perfectly reliable; in the second experiment, RoboLeader’s recommendations were manipulated to be either false-alarm prone or miss prone, with a reliability level of either 60% or 90%. The visual density of the targeting environment was manipulated by the presence or absence of friendly soldiers.

Results: RoboLeader, when perfectly reliable, was helpful in reducing the overall mission times. The type of RoboLeader imperfection (false-alarm vs. miss prone) affected operators’ performance of tasks involving visual scanning (target detection, route editing, and situation awareness). There was a consistent effect of visual density (clutter of the visual scene) for multiple performance measures. Participants’ attentional control and video gaming experience affected their overall multitasking performance. In both experiments, participants with greater spatial ability consistently outperformed their low-spatial-ability counterparts in tasks that required effective visual scanning.

Conclusion: Intelligent agents, such as RoboLeader, can benefit the overall human-robot teaming performance. However, the effects of type of agent unreliability, tasking requirements, and individual differences have complex effects on human-agent interaction.

Application: The current results will facilitate the implementation of robots in military settings and will provide useful data to designs of systems for multirobot control.
Innovative screening of novel bioengineered cotton fibers containing oligochitin
Authors: Ceylan Ö , Van Landuyt L , Van der Schueren L , Hauben M , De Block M , De Clerck K
Published: February 2012

The aim of this paper is to establish a test method for the screening of bioengineered cotton fibers with an improved reactivity through the incorporation of positively charged nitrogen moieties. For this purpose a spectrophotometric method based on the absorption of a negatively charged dye (Acid Orange 7) is extensively studied. The processing parameters have been optimized for analyzing small amounts of fibers and the feasibility of the method is examined by using two other well established techniques for nitrogen analysis. Good correlations were obtained between the different methods, however, the reproducibility of the Acid Orange 7 was superior to the other two methods. Moreover, statistically significant differences were found between fibers from cotton lines designed to produce oligochitin and control fibers without oligochitin. This shows that the proposed method is capable of accurately detecting increased nitrogen levels in bioengineered cotton fibers.
Investigation of bending and drape properties of woven fabrics and the effects of fabric constructional parameters and warp tension on these properties
Authors: Süle Gülcan
Published: February 2012

In this research, bending and drape properties of woven fabrics and the effect of weft density, weft yarn count and warp tension on these properties were investigated. Higher values were found for bending rigidities of the fabrics woven with thicker weft yarns and at higher weft densities. It was seen that bending rigidities of the fabrics in the warp directions increased as warp tension increased. Bending rigidities in the weft directions did not show any significant change, such as an increase or decrease depending on any change in warp tension. In the case of the fabrics woven with thicker weft yarns, the overall fabric bending rigidity increased as warp tension increased. Considering drape coefficients of the fabrics, it was observed that the drape coefficient increased as the weft density increased and weft yarn became thicker. The drape coefficient did not significantly vary depending on the variations in the warp tension.
Particle pair system: An interlaced mass-spring system for real-time woven fabric simulation
Authors: Zhang Jiahua , Baciu George , Cameron Justin , Hu Jin lian
Published: February 2012

Woven fabrics are widely used in clothing because of their parallel and interlaced properties, which are formed by weaving. A wide range of applications, from 3D games to textile design, adopt woven fabrics for cloth animation due to the fact that weaving can be immediately shown on the cloth. Today, cloth animation at the macro scale is successfully accomplished using single particle systems, processes of treating the cloths as sheets of single particles interconnected with spring-dampers. However, the existing single particle systems become limited when applied to show the interlaced structures between the yarns. In this paper, we introduce the particle pair system, a dynamics system of particle pairs for woven fabric simulation. It treats the woven fabric as an interlaced crimp network of weft particles and warp particles. Each weave point of the woven fabric is represented as a particle pair rather than a single particle, providing independent behaviors of particles in the weft direction and the warp direction, respectively. The particles are connected dynamically according to a connectivity matrix which allows for tearing. The atom of the system is the particle pair, a flexible representation that can be tessellated to panel quads at the macro scale, interlaced yarn segments at the meso scale and intertwisted fibers at the micro scale, according to the view distance, for fast rendering. The particle pair system can be easily implemented in current graphics pipelines. We can achieve more than 100 frames per second for a 256 × 256 woven fabric. This allows for large-scale physical animation of woven fabrics that maintain the geometric variances of real 3D yarn and fibers.
Investigation of wicking, wetting and drying properties of acrylic knitted fabrics
Authors: Yanılmaz Meltem , Kalaoğlu Fatma
Published: February 2012

In this study, it was aimed to investigate the relationship between different knitted structures and some thermo-physiological comfort parameters. Wetting, wicking and drying properties of single jersey, 1 × 1 rib, 2 × 2 rib and interlock knitted fabrics made out of acrylic yarns were studied and experimental wicking height, wicking weight, transfer wicking ratio, contact angle and WER (water evaporation rate) values were measured. Samples were produced in two different tightness values to obtain slack and tight fabrics for all structures. Some comfort-related parameters were correlated with structural parameters of fabrics such as fabric tightness factor, thickness, porosity, loop length and pore size etc. The statistical analysis results indicate that the effect of the knitted structure is significant for wicking height, wicking weight, contact angle values, transfer wicking ratios and WER values. Wicking height increases depending on knitted structures namely, single jersey, 1 × 1 rib, interlock and 2 × 2 rib, respectively. Slack fabrics have longer loop lengths with higher porosity values and higher pore sizes for all knitted structures. Slack structures of 2 × 2 rib, 1 × 1 rib, interlock and single jersey knits have higher transfer wicking ratios when compared with their tight structures. WER is inversely related with fabric thickness. It decreased with an increase of thickness due to increase of compactness and decrease of air space. All tight knitted structures have higher contact angles than their slack forms due to compactness of the surface.
Does quilting improve the fragment protective performance of body armour?
Authors: Carr Debra J , Lankester Claire , Peare Alan , Fabri Nicolas , Gridley Nicky
Published: February 2012

The primary function of military body armour is to provide protection from fragmenting munitions and improvised explosive devices (IEDs). This is usually achieved by the use of multiple layers of woven para-aramid fabric. The resulting body armour is heavy and contributes to the burden on the dismounted soldier. Reduction in body armour mass and hence thermophysiological loading without reducing the level of protection is therefore of interest worldwide. Many manufacturers quilt the fabric component of body armour which reportedly improves fragment protective performance, however, the topic does not appear to have been explored thoroughly. In this work a preliminary study on the effect of quilting on the fragment protective performance of a commercially available woven para-aramid fabric is reported. The fragment protective performance of specimens varying in construction (1, 2, 3 and 5 layers) with three quilting regimes (no quilting, diamond quilting, square quilting) is presented and analysed.
The Effects of Nonresponse Rates on Group-Level Correlations
Authors: Nesterkin Dmitriy A. , Ganster Daniel C.
Published: February 2012

This study investigates the effects of group member nonresponse in research that examines relationships between group-level constructs aggregated from the responses of individual group members. Simulation data show that the effects of nonresponse vary greatly depending on levels of between-group variability and within-group variability expressed jointly as intraclass correlation, or ICC(1), values. Even high response rates, for example, can produce significantly attenuated correlations between group-level variables with ICC(1) levels commonly reported in group studies. Conversely, even low response rates can yield accurate group-level correlations when ICC(1) levels are high. These effects of nonresponse are equivalent whether nonresponse derives from a random or biased process. Group size appears to play no important role in moderating the effects of response rate. Suggestions for research design and post hoc diagnosis of findings are discussed.
A Mixed-Methods Comparison of Vocational and Identified-Gifted High School Students on the Overexcitability Questionnaire
Authors: Piirto Jane , Fraas John
Published: February 2012

Two groups of adolescents ( N = 114), 61 identified-gifted adolescents ( M = 22, F = 39) and 51 vocational school adolescents ( M = 27, F = 26), were compared on the Overexcitability Questionnaire. Each of the five Overexcitability (OE) scores—Psychomotor, Sensual, Imaginational, Intellectual, and Emotional—was subjected to a two-way ANOVA by classification and gender. Any statistically significant interaction effect was further analyzed by testing the group means with six two-group comparison tests. The analyses produced the following results: (a) Differences among the Psychomotor, Sensual, and Emotional OE means were not statistically significant, and (b) the Imaginational and Intellectual OE means of the gifted male students were significantly higher than the means of the vocational female students, vocational male students, and gifted female students. The effect sizes were classified as large. A qualitative textual analysis was also conducted. The results were compared with another study of the same gifted population that used the Overexcitability Questionnaire-II.
The effect of acute exogenous melatonin on P50 suppression in healthy male volunteers stratified for low and high gating levels
Authors: Ucar Ebru , Lehtinen Emilia K , Glenthøj Birte Y , Oranje Bob
Published: February 2012

Sensory gating is frequently found to be disturbed in patients with schizophrenia. In addition, a disruption of the circadian rhythm together with a low nocturnal melatonin output is regularly found in these patients. Since there is some evidence that a brief period of sleep normalizes sensory gating in schizophrenia patients, it is conceivable that their disrupted melatonin level may contribute to the deficits in P50 suppression. In this initial study, the effects of acutely administered melatonin on sensory gating in healthy subjects were investigated. In a double-blind placebo-controlled crossover design, 21 healthy male volunteers were administered melatonin (4 mg) or placebo, after which they were tested in a P50 suppression paradigm. In the group as a whole, melatonin did not affect P50 suppression. However, melatonin increased the P50 ratio in the individuals with high baseline suppression. In contrast to what was expected, melatonin reduced P50 suppression, albeit only in those individuals with high baseline suppression. The current study does not support a beneficial effect of acute exposure to exogenous melatonin on sensory gating. Future research should focus on melatonin’s ability to restore basic sleep rhythms and its subsequent effects on sensory gating, in both healthy volunteers and patients with schizophrenia.
Rosiglitazone treatment reversed depression- but not psychosis-like behavior of db/db diabetic mice
Authors: Sharma Ajaykumar N , Elased Khalid M , Lucot James B
Published: February 2012

The objective of the present study was to examine the effect of long-term management of insulin resistance and hyperglycemia on neurobehavioral deficits in db/db mice. In this study, 5-week-old db/db and lean control mice were fed with rosiglitazone (20 mg/kg/day) mixed or standard chow for a duration of 5 weeks. Mice were monitored weekly for blood glucose concentration. Five weeks after the onset of treatment, they were subjected to the forced swim test (FST), pre-pulse inhibition (PPI), open field test (OFT) and fear-potentiated startle (FPS) test to examine for depression, psychosis-like behavior, locomotor activity and emotional learning, respectively. Rosiglitazone normalized hyperglycemia and improved glucose tolerance. Rosiglitazone significantly reduced immobility time in the FST in db/db mice, suggesting an antidepressant-like effect. However, rosiglitazone failed to reverse disruption of PPI in db/db mice, indicating its ineffectiveness against psychosis-like behavior. In the OFT, rosiglitazone did not affect the activity of db/db mice, suggesting its antidepressant-like effect was independent of changes in locomotor activity. In the FPS test, db/db mice showed impaired emotional learning and rosiglitazone failed to correct it. In conclusion, long-term blood glucose management in type-2 diabetics may help to limit the co-occurrence of depression but not the psychotic symptoms and ability to cope with stress.
Rotary ultrasonic machining of CFRP: A comparison with twist drilling
Authors: Cong W.L. , Pei Z.J. , Feng Q. , Deines T.W. , Treadwell C.
Published: February 2012

Drilling is involved in many applications of carbon fiber–reinforced plastic composite. Twist drilling is widely used in industry. Rotary ultrasonic machining has been successfully tested to drill holes in carbon fiber–reinforced plastic. However, there are no reports on comparisons between rotary ultrasonic machining and twist drilling of carbon fiber-reinforced plastic. This paper compares rotary ultrasonic machining and twist drilling of carbon fiber–reinforced plastic in six aspects (cutting force, torque, surface roughness, delamination, tool life, and material remove rate). Experimental results show that rotary ultrasonic machining is superior in almost all these aspects.
Prepreg age monitoring via differential scanning calorimetry
Authors: Grunenfelder Lessa K. , Nutt Steven R.
Published: February 2012

Fabrication of composite parts from prepregs often requires layup and preparation times of days and even weeks, during which prepregs undergo room-temperature aging. The aging process can compromise compaction, tack, and overall quality of composite parts, and thus a need exists for an accurate and convenient method to monitor the extent of prepreg aging as a function of out-time. Here, we report a method to monitor prepreg age, which involves measurement of changes in glass transition temperature as a function of room-temperature aging time. Samples from three out-of-autoclave prepreg systems were aged in ambient conditions and tested periodically using modulated differential scanning calorimetry. A linear increase in glass transition temperature with prepreg age was noted. Results are discussed in the context of monitoring the chemical aging of epoxy resins that occurs at ambient temperature.
A study on moisture absorption and swelling in bio-based jute-epoxy composites
Authors: Masoodi Reza , Pillai Krishna M.
Published: February 2012

Woven jute fibers, a class of affordable and biodegradable ‘green’ fibers, are being increasingly used as a substitute for the artificial glass and carbon fibers used in polymer composites. However, all natural fiber composites absorb water and swell in a moist environment For the first time, the swelling and weight gain behavior of bio-based composites made from jute fibers and bio-based or ordinary epoxy is presented in this experimental characterization study. Several such composites specimens were made using a low-pressure resin injection process similar to resin transfer molding; the specimens were made according to ASTM D 570 consisted of three compositions: pure resin, pure resin with a single jute fabric layer, and pure resin with two jute fabric layers. The effects of number of layers on moisture absorption, thickness swelling, volume swelling, and density were measured as a function of immersion time. It is observed that the moisture diffusion rate into composites increases with an increase in the jute-fiber-to-epoxy ratio. The type of epoxy used as the matrix appeared to have an influence on the moisture absorption percentages of the composites – the study showed that both water absorption and swellings were higher in the bio-epoxy parts compared to the epoxy parts. The swelling of composites was correlated with an increase in diameters of jute fiber in water and possibilities for the appearance of micro-cracks around fibers in composites were discussed. The data on moisture absorption, thickness swelling, and volume swelling of bio-based composites made from woven jute fibers, and bio-based and ordinary epoxies presented in this article will lead to a better understanding of how these composites react in wet environmental conditions.
Micro-structural, thermal, and mechanical properties of injection-molded glass fiber/nanoclay/polypropylene composites
Authors: Rahman Normasmira Abd. , Hassan Aziz , Yahya Rosiyah , Lafia-Araga R.A. , Hornsby Peter R.
Published: February 2012

Hybrid composites of PP/NC/GF were prepared by extrusion and injection molding. Molded specimens were analyzed by XRD, SEM, and TEM, together with characterization of thermal and mechanical properties. XRD results revealed that the interaction between NC particles and the PP matrix results in intercalation of the polymer chains, which increases the clay interlayer distance. TEM results revealed NC particle intercalation. TGA results showed that the incorporation of clay into the GF composite improves the thermal stability of the material. The initial thermal decomposition temperatures also shifted to higher values. Incorporation of GF into PP lowers the tensile strength of the binary composite, indicating poor fiber–matrix interfacial adhesion; however, introducing NC increased the strength of the ternary composites. Tensile modulus was enhanced with the incorporation of GF and further increased with an introduction of NC. Flexural strength and flexural modulus are both enhanced with an increase in fiber loading. The addition of clay nanoparticles further improved these properties.
Morphology, mechanical, and crystallization behaviors of micro- and nano-ZnO filled polypropylene composites
Authors: Zaman Haydar U. , Hun Park Deuk , Khan Ruhul A. , Yoon Keun-Byoung
Published: February 2012

The aim of this study was to study the effect of ZnO concentration on the morphology, mechanical, and crystallization behaviors of iPP. Three compositions of iPP/mZnO and iPP/nZnO composites were prepared in a co-rotational twin-screw extruder machine with ZnO content of 2 wt%, 5 wt%, and 8 wt%. Tensile tests showed that the tensile strength at yield and tensile modulus of the composites tended to increase with increasing contents of mZnO/nZnO particles. This improvement in the tensile properties was attributed to good interfacial adhesion between the fillers and the matrix, as evidenced by TEM examination. The tensile strength at yield and tensile modulus values of iPP/nZnO composite with the addition of 2–8 wt% nZnO are higher than those of virgin iPP, and even higher than those of iPP/mZnO composite with the addition of 2–8 wt% mZnO. The non-isothermal crystallization behavior of iPP/mZnO and iPP/nZnO composites was investigated using DSC. The results indicated that the interfacial interaction between iPP and mZnO/nZnO increased the crystallization temperature when the content of ZnO is 5 wt%.
Development and anti-bending behavior of a ‘π’ shape 3D woven composite
Authors: Jiang Jiasong , Liao Chunxiao , Zhou Luoqing
Published: February 2012

Hollow woven composites are widely used as matrix in aeronautics and vehicles. This paper develops a new ‘π’ shape of 3D woven hollow composite to optimize its bending property. The new structure composite is woven with overlapping warp integral panel enhancing method. In order to weave it out, a new structure of heald has been innovated. Three specimens with different thickness of panels are manufactured by this method. The anti-bending performances of the composites are carried out by four-point bending tests. The experimental results show that with an increase of the number of the composites layers, the Young's modulus and failure loads of the composites are increased significantly.
Numerical simulation of LCM mold-filling during the manufacture of natural fiber composites
Authors: Masoodi Reza , Pillai Krishna M , Grahl Nick , Tan Hua
Published: February 2012

In this paper, a finite element/control volume (FE/CV) method based computer code is adapted to simulate the flow of resin-like liquids in swelling jute fabrics during the manufacture of natural-fiber composites using the liquid composite molding (LCM) technique. A novel treatment of the continuity equation using the rigorous volume-averaging method indicates that the despite liquid absorption and fiber swelling, the form of the continuity equation may remain identical to the traditional form seen for non-absorbing carbon or glass fibers. Such a continuity equation in conjunction with the Darcy’s law with a time-varying permeability function is employed to model the resin flow as a fully saturated porous medium flow behind a clearly defined liquid front. Two new methods of estimating the time-varying local permeability and porosity of the wetted fiber mats behind the moving liquid-front are proposed. Later, the two time-dependent permeability models, one based on direct experimental estimation and the other based on indirect estimation using the Kozeny-Carman model, are used to alter permeability in finite elements behind the moving liquid-front during the numerical simulation. Such numerical modeling of the mold-filling process, as applied to the one-dimensional flows with constant flow rate and constant injection-pressure conditions, shows significant improvement over the traditional analytical solution obtained for a constant permeability. A good prediction of the experimentally observed flow-front location and inlet-pressure evolution plots by the two permeability models is observed. Of the two permeability models, the one based on direct estimation of permeability is found to be superior to the one employing the indirect approach. The novel analytical solution developed for the constant flow-rate (one-dimensional flow) case under a time-dependent permeability is shown to perform extremely well while predicting the flow-front location and inlet pressure evolution.
Revisiting the Normal Crime and Liberation Hypotheses
Authors: Wu Jawjeong , DeLone Miriam A.
Published: February 2012

The established sentencing scholarship focusing on race/ethnicity and sentencing disparity indicates that the effect of race/ethnicity on sentencing severity varies across offense types. However, it is not clear whether this argument holds true when race/ethnicity is replaced with offender citizenship status as the primary variable of interest. In light of the research gap, this study extends beyond the existing literature exclusively on race/ethnicity by investigating the nexus between citizenship status, offense types, and sentencing outcomes through the normal crime hypothesis and the liberation hypothesis. Using the Monitoring of Federal Criminal Sentences data that include information on all offenders sentenced in 17 federal district courts for fiscal years 2006–2008, the present study assesses the independent and interactive effects of citizenship status and offense types on the judicial sentence length decision. Findings reveal that although models fail to support the normal crime hypothesis, there is robust support for the liberation hypothesis.
Light and ultrastructural study in the propylthiouracil-induced hypothyroid rat heart ventricles and the ameliorating role of folic acid
Authors: Massoud Ahmed A , El-Atrash Afaf , Tousson Ehab , Ibrahim Wafaa , Abou-Harga Heba
Published: February 2012

Thyroid hormones have marked effects on the growth, development, and metabolic function of virtually all organs and tissues. Thyroid status is an important determinant of cardiovascular function. The present work studied the histopathological and ultrastructural changes in the hypothyroid rat left ventricle at post-pubertal stage, in addition to the ameliorating role of folic acid. A total of 50 male albino rats were randomly divided into 5 groups (group I, control; group II, folic acid; group III, propylthiouracil-induced hypothyroid rats; group IV, co-treatment with folic acid; group V, post-treatment). In order to ensure the hypothyroid state, the level of serum triiodothyronine (T3) and thyroid stimulating hormone (TSH) through the dose period was regularly determined. The TSH levels were significantly higher while T3 levels were significantly lower in hypothyroid rats when compared to control group. The high-performance liquid chromatography analysis showed an increase in homocysteine (Hcy) in the hypothyroid rats group when compared to the control group. The histopathological studies of the ventricle in hypothyroid rats revealed hydrophobic changes in myofibrillar structure with striations, myocardial atrophy, nuclear pyknosis, cytoplasmic vacuoles, and cytoplasmic eosinophilia. Transmission electron micrographs in the myocardium of hypothyroid rats revealed a marked reduction in muscle fibre mass, a marked degeneration of muscle fibres, swollen mitochondria, dilated sarcoplasmic reticulum and more prominent perinuclear oedema observed in the cardiac myocytes. In co-treated hypothyroid rats with folic acid, a regular arrangement of muscle fibres, mild swelling of myofibrillar structure with striations and no continuity with adjacent myofibrils were observed while the post-treated hypothyroid rat with folic acid showed normal architecture of myofibrillar structure with striations and continuity with adjacent myofibrils. In conclusion, our results indicated that folic acid had ameliorative effect against cardiac damage induced by 6- n-propyl-2-thiouracil and the best results were found in case of using the folic acid as an adjuvant therapy after returning to the euthyroid state.
Implicit Attitudes Toward Violence Among Male Perpetrators of Intimate Partner Violence
Authors: Eckhardt Christopher I. , Samper Rita , Suhr Laura , Holtzworth-Munroe Amy
Published: February 2012

Whereas cognitive variables are hypothesized to play an important role in intimate partner violence (IPV) etiology and intervention, cognitive assessment methods have largely targeted offenders’ explicit, controlled cognitive processing using paper-and-pencil questionnaires prone to social desirability biases. Using an implicit measure of attitudes (the Implicit Association Test [IAT]), we assessed attitudes toward gender, violence, and the association between gender and violence among 50 men enrolled in an IPV treatment program and a comparison sample of 40 nonviolent (NV) men. Although no group differences were noted on explicit attitudinal measures, men in the IPV group showed more positive implicit attitudes regarding violence, and a more rapid association between women and violence. Among men in treatment for IPV, the attitudes toward violence IAT was significantly correlated with self/partner-reported IPV frequency. In accordance with social information processing models of aggression, these results suggest that aggressogenic attitudes are likely to operate automatically and with little conscious deliberation. As a result, clinicians and researchers must adapt assessment and intervention strategies to capture both implicit and explicit aspects of cognitive processing.
Exploring What Greening the Economy Means for African American Workers, Entrepreneurs, and Communities
Authors: Harper-Anderson Elsie
Published: February 2012

As the United States recovers from the worst economic crisis in 80 years, both environmental and economic epidemics are disproportionally affecting communities of color. The U.S. unemployment rate stands near 10%. Yet for African Americans in some areas, it is twice as high. Simultaneously, the world is threatened by the effects of climate change and increasing environmental health issues, whereas communities of color are overburdened by environmental injustices. The Obama administration has invested heavily in policies to “green the economy” as a strategy to preserve the environment while stimulating economic recovery in large part through The American Reinvestment and Recovery Act of 2009. Although this strategy has yielded tremendous opportunity, resource distribution has been uneven across geographic areas and demographic groups. Unfortunately, some of our nation’s neediest people and communities are being left out of the green revolution. This essay discusses the impact of “greening the economy” for African Americans and suggests possible steps toward addressing inequality in resource access and distribution.
Suburban Origins of the Tea Party: Spatial Dimensions of the New Conservative Personality
Authors: Thompson Michael J.
Published: February 2012

This article explores the hypothesis that the wellsprings of the recent upswing in new conservative movements such as the Tea Party can be found in the socio-spatial context within which individuals are socialized. Non-urban forms of space possess certain social and structural characteristics that can shape styles of moral cognition that in turn lead to conservative predispositions within the personality structure of the individual. Suburban and exurban spaces tend to provide a context for new conservative world-views as a result of the ways social interaction shapes the moral-cognitive style of individuals. Dogmatic moral cognition is shaped by constrained forms of socialization that affect the ways individuals conceive their world and distort certain epistemic capacities. When activated by different forms of social threat or social change, they will be more inclined to turn to conservative movements and ideologies that express their insecurity and social anxieties that are themselves produced by the world-views within which they feel comfort and security.
Neither a Borrower Nor a Lender Be
Authors: Drentea Patricia , Reynolds John R.
Published: February 2012

Objective:This study examines the impact of indebtedness on depressive symptomatology, anxiety, and anger. Method: We use data from a two-wave panel study of adults in Miami-Dade County. The analytic sample consists of 1,463 mostly older respondents with valid data on all study measures, including education, income, occupational status, wealth, and debt. Results: We find that indebtedness is common and is associated with more symptoms of depression, anxiety, and anger. It is weakly associated with other aspects of socioeconomic status (SES), and thus not redundant with them. In fact, in this sample, debtor status is more consistently associated with mental health than any other single traditional indicator of SES, its effect does not vary across income or other aspects of SES, and fears of never paying off debt account for its negative impact on mental health. Discussion: These findings affirm health scholars’ calls for more complete measures of SES.