Survival of environmental and clinical strains of methicillin-resistant Staphylococcus aureus [MRSA] in marine and fresh waters

Recent studies have found variable levels of methicillin-resistant Staphylococcus aureus [MRSA] in marine water from temperate and warmer climates suggesting that temperature may play a role in survival of MRSA in the environment. The aim of the study was to compare the survival of clinical and environmental MRSA and MSSA strains in fresh and marine water incubated at 13 °C and 20 °C over 14 days. Seven different MRSA strains and the MSSA ATCC 25923 were tested. Individual strains were diluted in sterile saline to a 0.5 McFarland standard (10⁸ cfu/ml), serially diluted in duplicate to a final concentration of 10⁵ cfu/ml in pooled filter-sterilized marine or fresh water and incubated at 13 °C or 20 °C in the dark. The results of this study found that temperature and salinity are important factors in MRSA and MSSA survival; the decay rate was ∼28% higher at 20 °C versus 13 °C and ∼34-44% higher in fresh water versus marine water. There was no statistical difference between environmental and clinical MRSA strain survival [P = 0.138]. The study found that MRSA/MSSA survival was significantly longer in marine water at 13 °C typical of the Pacific Northwest, which may have important implications for recreational beach visitors in colder climates.     

Effects of chitosan on the physicochemical and antimicrobial properties of PLA films

Films based on polylactic acid (PLA) and different amounts of chitosan powder (CH), were prepared by extrusion. The effects of CH particle size (715 and 180 μm) and the amount of chitosan incorporated in the PLA matrix (5% or 10% on PLA basis) were investigated in terms of physicochemical characteristics and antimicrobial activity of the films. The incorporation of CH particles led to less rigid and less stretchable films. Thermal properties of PLA were not affected by chitosan addition. Water vapor permeability of the composite films was higher than pure PLA films. PLA:CH composite showed significant antimicrobial activity against total aerobial and coliform microorganisms, especially when the particle size of CH was reduced.     

Structural and electrical characteristics of Sr(Fe2/3W1/3)O3 ceramics

The polycrystalline samples of Sr(Fe_2/3W_1/3)O₃ (SFW) were prepared by a high-energy ball-milling followed by solid-state reaction technique. The X-ray structural analysis showed the formation of single-phase compound in the tetragonal system, which is a distorted structure of an ideal cubic perovskite. The temperature–frequency dependence of dielectric constant and loss tangent exhibited relaxation behavior of the compound. The studies of impedance parameters (Z′, Z″) as a function of temperature and frequency have confirmed the contribution of bulk resistance of SFW. The small value of activation energy of the compound (～ 0.35 eV) can be explained by mixed ionic–polaronic conductivity mechanism.     

"The Differentiation of Self Inventory: Development and initial validation": Errata.

Reports an error in "The Differentiation of Self Inventory: Development and initial validation" by Elizabeth A. Skowron and Myrna L. Friedlander (Journal of Counseling Psychology, 1998[Jul], Vol 45[3], 235-246). In the January 1998 edition of the Journal of Counseling Psychology (Volume 45, Number 3, p. 246), the key to the Appendix was printed incorrectly. Please see the attached errata for further information. (The following abstract of the original article appeared in record 1998-04269-001.) Despite the importance of Bowen theory (M. Bowen, 1976,1978; M. E. Kerr & Bowen, 1988) in the field of family therapy, there have been relatively few studies to date examining its constructs or propositions. To fill this gap, a self-report instrument, the Differentiation of Self Inventory (DSI) has been developed. The DSI is a multidimensional measure of differentiation that focuses specifically on adults (age 25+), their significant relationships, and current relations with family of origin. Six-hundred and nine adults participated in a series of 3 studies, in which DSI scores—reflecting less emotional reactivity, cutoff, and fusion with others, and a greater ability to take an "I position"—predicted lower chronic anxiety, better psychological adjustment, and greater marital satisfaction. Other results consistent with Bowen theory are discussed, along with the potential contribution of the DSI for testing Bowen theory, as a clinical assessment tool, and as an indicator of psychotherapeutic outcome. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Chemical Ecology of Soil Organic Matter Molecular Constituents

Soil organic matter (OM) contains vast stores of carbon, and directly supports microbial, plant, and animal life by retaining essential nutrients and water in the soil. Soil OM plays important roles in biological, chemical, and physical processes within the soil, and arguably plays a major role in maintaining long-term ecological stability in a changing world. Despite its importance, there is a great deal still unknown about soil OM chemical ecology. The development of sophisticated analytical methods have reshaped our understanding of soil OM composition, which is now believed to be comprised of plant and microbial products at various stages of decomposition. The methods also have recently been applied to study environmental change in various settings and have provided unique insight with respect to soil OM chemical ecology. The goal of this review is to highlight the methods used to characterize soil OM structure, source, and degradation that have enabled precise observations of OM and associated ecological shifts. Although the chemistry of soil OM is important in its overall fate in ecosystems, the studies conducted to date suggest that ecological function is not defined by soil OM chemistry alone. The long-standing questions regarding soil OM stability and recalcitrance will likely be answered when several molecular methods are used in tandem to closely examine structure, source, age, degradation stage, and interactions of specific OM components in soil.     

Fear gradients as a function of the temporal interval between signal and aversive event in the rat.

The degree of response suppression was measured in 5-sec intervals during a signal that was associated with electric shock. Four groups of 6 naive male albino Norway Charles River CD rats were tested with signals of fixed or random duration and with shocks that occurred at the end of the signal or at random times during the signal. In all cases, there was a transient effect of the onset of the signal, but thereafter, the 4 groups showed qualitatively different fear gradients. The magnitude of fear was closely related to the expected time to the next shock. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dynamics of electric-field domains and chaos in semiconductor superlattices

A discrete drift model of sequential resonant tunneling in weakly-coupled doped or undoped GaAs/AlAs superlattices (SL) under d.c. or d.c. + a.c. voltage bias and laser illumination is analyzed. In agreement with experiments our model shows an oscillatory I-V diagram for large enough values of the doping and/or laser illumination, multistability and hysteresis between stationary solutions and self-sustained time dependent oscillations of the current. Numerical and asymptotic analyses of the model show that these current oscillations are due to the formation, motion, annihilation and regeneration of negatively charged domain walls on the SL. For appropriate d.c. + a.c. voltage bias, chaotic current oscillations with loss of spatial coherence of the electric field will appear due to random nucleation of domains in the SL.     

Trainees' experiences of role conflict and role ambiguity in supervisory relationships.

The nature and extent of counselor trainees' experiences with role difficulties were examined in the context of supervision. Role ambiguity arises when trainees are unsure of supervisory expectations for their performance or evaluation; role conflict arises when trainees encounter opposing expectations for their behavior. The Role Conflict and Role Ambiguity Inventory was developed and validated with trainees and supervisors in practicum, internship, and postinternship settings. Results indicate that the inventory is both reliable and valid. As hypothesized, role difficulties were predictive of more work-related anxiety, general work dissatisfaction, and dissatisfaction with supervision. Beginning trainees reported higher levels of role ambiguity than did more experienced trainees. Role conflict seems to be problematic only for advanced trainees, for whom ambiguity is minimal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)