Radiochemical neutron activation analysis of zinc isotopes in human blood, urine, and feces for in vivo tracer experiments

Enriched stable isotopes are being increasingly used for study of trace element nutrition in humans who cannot be studied by use of in vivo radioactive tracers (e.g., subjects under age 18 and pregnant women). Zinc metabolism in these subjects can be evaluated by administration of Zn enriched to 65% in the minor isotope, 70Zn (0.6% natural abundance). The enhanced 70Zn is detected later in red blood cells, plasma, urine, and feces by measuring 70Zn/64Zn or 70Zn/68Zn ratios. Stable isotope concentrations are measured by neutron activation of the samples and observation of their products: 244-day 65Zn, 14-h 69mZn, and 4-h 71mZn. Zinc-65 can be observed in these samples without chemical separations 3 weeks after irradiations, but large amounts of 24Na and other short-lived species preclude direct observation of the short-lived Zn activities. Preirradiation chemistry was developed to remove most interferences, the major steps being to place the sample on Chelex resin, elute alkali metals and alkaline earths from it, and irradiate the resin containing the Zn. gamma-Rays of 69mZn can be observed on the irradiated resin, but additional precipitation and solvent extraction steps are needed to remove 56Mn and 64Cu for clear observation of 71mZn and 65Zn within hours after irradiation. Yields for pre- and postirradiation separations are typically 85% and 70%, respectively. The stable isotope tracer method was validated by simultaneous in vivo tracing with radioactive 65Zn in four subjects.     

Energy and exergy analysis of Salihli geothermal district heating system in Manisa,Turkey

This study deals with an energy and exergy analysis of Salihli geothermal district heating system (SGDHS) in Manisa, Turkey. In the analysis, actual system data are used to assess the district heating system performance, energy and exergy efficiencies, specific exergy index, exergetic improvement potential and exergy losses. Energy and exergy losses throughout the SGDHS are quantified and illustrated in the flow diagram. The exergy losses in the system, particularly due to the fluid flow, take place in the pumps and the heat exchanger, as well as the exergy losses of the thermal water (e.g. geothermal fluid) and the natural direct discharge of the system. As a result, the total exergy losses account for 2.22, 17.88 and 20.44%, respectively, of the total exergy input to the entire SGDHS. The overall energy and exergy efficiencies of the SGDHS components are also studied to evaluate their individual performances and determined to be 55.5 and 59.4%, respectively. Copyright © 2005 John Wiley & Sons, Ltd.     

Age-dependent deficits in spatial memory are related to impaired hippocampal kindling.

21 3-mo-old and 25 26-mo-old Fischer 334 rats were tested in an 8-arm maze in a behavioral assessment of spatial memory (SM) before undergoing hippocampal kindling (HK) to examine alterations in neuronal plasticity as a function of aging. Results indicate a positive relation between maze performance and speed of HK and that SM was poorer and HK slower in 26-mo-olds than in 3-mo-olds. Age-related deficits in SM and HK may reflect decreased efficacy of synaptic transmission in a common neuroanatomical substrate. (52 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of frontal cortex in social odor discrimination and scent-marking in female golden hamsters (Mesocricetus auratus).

Orbital/agranular insular (ORB/AI) cortex has been implicated in traditional olfactory learning tasks and social behavior but its precise role in discriminating-learning social odors is not known. Female golden hamsters received aspiration lesions of ORB/AI or dorsomedial (DM) frontal cortex and were tested for their ability to (a) discriminate between odors of individual males in a habituation-discrimination task, (b) show preferences for male over female odors, and (c) scent-mark in response to male odors. Lesioned females readily discriminated between scents of individual males. Neither lesion altered female preferences for male odors. Females with DM lesions showed increased levels of scent marking to male odors, but those with ORB/AI cortex lesions did not differ from controls. Thus, ORB/AI cortex does not appear to be critical for discrimination of odors of individuals or sex or for scent-marking responses based on these discriminations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The glass transition behaviour and thermodynamic properties of amorphous polystyrene

The effect of molecular weight (MW) and thermal history on the heat capacity (c_p) of amorphous polystyrene over the temperature range from 200–440 K has been measured using differential scanning calorimetry (d.s.c.) General equations are given that show the influence of MW on c_p in both the glassy and liquid states. An enthalpic definition of the glass temperature reflects changes in the glass structure, due to thermal history, that are not found using conventional d.s.c. constructions. Thermodynamic and statistical mechanical theories give reasonable approximations to the observed T_g-MW curve but small systematic deviations are found. The effect of thermal history on T_g can be reproduced using a MW-dependent activation enthalpy.     

Investigating the Blusa: The Cultural and Sartorial Biography of an Algerian Dress

This essay describes the evolution of the garment known as a blusa, worn by urban women in north-western Algeria. The blusa, a full-length dress with short sleeves, was conceived and developed in the cities of Tlemcen and Oran. It incorporates locally meaningful traditions as well as fashion styles in conjunction with different cultures. Its transformation illustrates how Algerian women resisted cultural assimilation through dress while creatively appropriating western European textiles, techniques and aesthetics in their clothing, during the French colonial period (1830–1962) and its aftermath. The exploration of the contemporary blusa variations reveals how the relationship between clothing and identity is still highly complex in Algerian cities. To date, the invention, the rituals, the design, and the production of the blusa dress has been little studied. This paper reconstitutes an historical puzzle based on recent object-based research and anthropological investigations. It seeks to interpret the blusa as an interface between tradition and modernity.     

Some results on disturbance attenuation for Hamiltonian systems via direct discrete‐time design

The disturbance attenuation and robust disturbance attenuation problems for Hamiltonian systems in the discrete‐time setting are considered and some new results are presented. The new results are derived utilizing the recently presented dissipativity equality obtained by adding the dissipation rate function to the classical dissipativity inequality. A selection of the dissipation rate function yields new results. These results include a condition on the dissipation structure of the system to achieve the desired disturbance attenuation level and gives direct construction of optimal control laws for any desired disturbance attenuation level. The results remove the need to solve Hamilton–Jacobi–Isaacs inequalities. Copyright © 2014 John Wiley & Sons, Ltd.     

Two approaches for solving the buffer allocation problem in unreliable production lines

This paper presents an integrated approach to solve the buffer allocation problem in unreliable production lines so as to maximize the throughput rate of the line with minimum total buffer size. The proposed integrated approach has two control loops; the inner loop and the outer loop. While the inner loop control includes an adaptive tabu search algorithm proposed by Demir et al. [8], binary search and tabu search are proposed for the outer loop. These nested loops aim at minimizing the total buffer size to achieve the desired throughput level. To improve the efficiency of the proposed tabu search, alternative neighborhood generation mechanisms are developed. The performances of the proposed algorithms are evaluated by extensive computational experimentation, and the results are reported.     

Exploring urban students’ constructions about school, work, race, and ethnicity.

This qualitative study is an exploration of 32 urban high school students’ narratives about the connection between school, work, and societal expectations of their future success related to their racial and ethnic background. The sample varied along 2 contextual dimensions: participation in a psychoeducational intervention (Tools for Tomorrow) and developmental status (i.e., half the sample were 9th-grade students and the other half were 12th-grade students). Using consensual qualitative research, the narratives revealed 3 major domains: future orientation; students’ perceptions of society’s expectations based on race and ethnicity; and students’ perception of the role of their race and ethnicity in future success. Results reveal that the majority of students endorse a connection between school and work, believe that society holds low expectations for them based on their racial and ethnic background, and cannot predict their future success based on their background. (PsycINFO Database Record (c) 2010 APA, all rights reserved)