Adaptive response: modelling and experimental studies

Adaptive response (AR) is a term that has been generally accepted to describe the ability of a low 'priming' radiation dose to decrease the cell response to a subsequent higher 'challenging' dose. The main proposed mechanisms to explain AR are: increased efficiency of DNA repair and induction of antioxidant enzymes. A model that considers a modulation of the efficiency of DNA repair activity and of the level of antioxidant enzymes, starting from the framework of a lethal-potentially lethal (LPL) model is proposed. The LPL model has been extended with the inclusion of the dynamic variables representing the efficiency of repair, the levels of radiation induced radicals and of antioxidant enzymes. The model used here is able to describe the protective effect of a priming dose. Moreover, in agreement with the data in the literature, the simulations show that the AR happens in given priming dose and priming dose-rate ranges only, and requires at least 4 h to develop. In order to get more insights into the role of cell-cell communication as factors affecting the AR, experimental studies were planned using sparse or confluent AG1522 cell monolayer. The results obtained after gamma irradiation suggest that cell density is a crucial factor for observing an AR.     

Measurements of isoprene-derived organosulfates in ambient aerosols by aerosol time-of-flight mass spectrometry - part 1: single particle atmospheric observations in Atlanta

Organosulfate species have recently been identified as a potentially significant class of secondary organic aerosol (SOA) species, yet little is known about their behavior in the atmosphere. In this work, organosulfates were observed in individual ambient aerosols using single particle mass spectrometry in Atlanta, GA during the 2002 Aerosol Nucleation and Characterization Experiment (ANARChE) and the 2008 August Mini-Intensive Gas and Aerosol Study (AMIGAS). Organosulfates derived from biogenically produced isoprene were detected as deprotonated molecular ions in negative-ion spectra measured by aerosol time-of-flight mass spectrometry; comparison to high-resolution mass spectrometry data obtained from filter samples corroborated the peak assignments. The size-resolved chemical composition measurements revealed that organosulfate species were mostly detected in submicrometer aerosols and across a range of aerosols from different sources, consistent with secondary reaction products. Detection of organosulfates in a large fraction of negative-ion ambient spectra - ca. 90-95% during ANARChE and ~65% of submicrometer particles in AMIGAS - highlights the ubiquity of organosulfate species in the ambient aerosols of biogenically influenced urban environments.     

Silver Stars: Silver–Polymer Composite Stars: Synthesis and Applications (Adv. Funct. Mater. 9/2011)

Colloidal “silver stars” were synthesized upon poly(lactic‐co‐glycolic) acid nanosphere templates via a facile two‐step silver reduction method. Myriad dendrimer‐like Ag star morphologies were synthesized by varying the amount of poly(vinyl alcohol) and trisodium citrate used during silver reduction. Scanning electron microscopy studies revealed that star‐shaped silver–polymer composites possessing nanoscopic, fractal morphologies with diameters ranging from 500 nm to 7 μm were produced. These composites have broad applications from antibacterial agents to catalysis; two such applications were tested here. Surface‐enhanced Raman spectroscopy (SERS) studies showed multiple hot spots of SERS activity within a single star. Electrochemical catalysis experiments demonstrated the feasibility of using the silver stars instead of platinum for the oxygen reduction reaction in alkaline fuel cells.     

Approach for measuring the chemistry of individual particles in the size range critical for cloud formation

Aerosol particles, especially those ranging from 50 to 200 nm, strongly impact climate by serving as nuclei upon which water condenses and cloud droplets form. However, the small number of analytical methods capable of measuring the composition of particles in this size range, particularly at the individual particle level, has limited our knowledge of cloud condensation nuclei (CCN) composition and hence our understanding of aerosols effect on climate. To obtain more insight into particles in this size range, we developed a method which couples a growth tube (GT) to an ultrafine aerosol time-of-flight mass spectrometer (UF-ATOFMS), a combination that allows in situ measurements of the composition of individual particles as small as 38 nm. The growth tube uses water to grow particles to larger sizes so they can be optically detected by the UF-ATOFMS, extending the size range to below 100 nm with no discernible changes in particle composition. To gain further insight into the temporal variability of aerosol chemistry and sources, the GT-UF-ATOFMS was used for online continuous measurements over a period of 3 days.     

An approach to the reliability optimization of software withredundancy

An approach to the optimization of software reliability is proposed. The emphasis is put on the software redundancy to achieve fault tolerance, i.e. the results of the optimization process are used to determine the optimal structure of the software to be developed. Two optimization models are formulated covering, respectively, modified recovery block scheme and multiversion programming approaches. Both cases are illustrated by simple examples. The models show that it is possible to formulate and solve some software related reliability optimization problems. They further show that the concept of redundancy to achieve fault tolerance (basic for the traditional theory of reliability) can be used in the field of software reliability optimization     

Forward telescoping: the question matters

This study examines the effect of pulse repetition rate (PRR), pulse intensity, and bicuculline on the minimum threshold (MT) and latency of inferior collicular neurons of the big brown bat, Eptesicus fuscus, under free-field stimulation conditions. It tests the hypothesis that changes in MT and latency of collicular neurons are co-dependent on PRR. The number of impulses in inferior collicular neurons (n = 245) increased either monotonically (25%) or non-monotonically (75%) with pulse intensity. Latencies either decreased to a plateau (72%), fluctuated unpredictably within 3 ms (21%) or changed very little (7%) with increasing pulse intensity. Latencies and MTs of most collicular neurons increased by 1.5-24 ms (mean +/- SD = 4.8 +/- 3.3 ms) and 4-75 dB (mean +/- SD = 22.1 +/- 16.2 dB) with increasing PRR. In most neurons (94%), the latency increase was completely (42%) or partially (52%) eliminated when pulse intensity was compensated for the MT increase with PRR. Complete elimination of latency was achieved by bicuculline application. In a few neurons (6%), the latency increase with PRR was not affected by compensated pulse intensity or bicuculline application.     

Cystic dilation of extrahepatic bile ducts in adulthood: diagnosis, surgical treatment and long-term results

To evaluate the long-term results of surgery for choledohal cyst in adulthood, a series of 13 patients over the age of 16 operated on for choledochal cyst during a period of six years and followed-up for a minimum of 3 years was analyzed. Patients with type I and IVa cysts underwent extrahepatic cyst resection and Roux-en-Y hepatico-jejunostomy. Choledochoceles (type III) were managed endoscopically. No operative mortality or morbidity occurred. Type I and III cysts showed almost ideal follow-up with no sign of stricture on HIDA scan. One type IVa cyst patients developed recurrent cholangitis due to anastomotic stricture, managed percutaneously. Whenever possible, complete cyst resection and Roux-en-Y reconstruction is the treatment of choice for all extrahepatic biliary cysts. Intra- and extrahepatic dilatations are adequately treated by extrahepatic resection and careful endoscopic or radiologic surveillance. Small choledochoceles can be safely managed by endoscopic sphincterotomy.     

Role of Interfacial Gaseous Heat Transfer in the Transverse Thermal Conductivity of a Uniaxial Carbon Fiber-Reinforced Aluminoborosilicate Glass

The transverse thermal conductivity of an aluminoborosilicate glass uniaxially reinforced with carbon fibers was found to be lower under near-vacuum than in nitrogen, whereas no such difference was found for the longitudinal thermal conductivity. This effect was attributed to the existence of an interfacial gap resulting from the thermal expansion mismatch between the matrix and fibers. The presence of this gap permits the gaseous environment access to the fiber-matrix interface and thereby contributes to the interfacial heat transfer. Its presence does not affect the longitudinal thermal conductivity, however, because the gap is aligned parallel to the fibers and, therefore, the direction of heat flow. Analysis of the experimental data indicates that, in nitrogen at atmospheric pressure, the gaseous conductance constitutes about one-third of the total interfacial conductance.     

A qualitative analysis of factors influencing the interpersonal dynamics of a prereferral team.

The reauthorized Individuals with Disabilities Education Improvement Act (IDEIA) encourages the use of problem-solving prereferral approaches and permits local education agencies to use 15% of federal funds for early intervention services for students who have not been identified as needing special education but who need additional academic and behavioral support to succeed in a general education environment. There is limited knowledge about the process prereferral teams use in a problem-solving approach and about desirable team practices. The purpose of this qualitative study was to examine the factors influencing the interpersonal dynamics of a prereferral process nominated as exemplary by district administrators. An awareness of the factors affecting the interpersonal interactions of prereferral teams may guide states in developing the early intervention services envisioned by the IDEIA. Implications for school psychologists and directions for future research are also discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of the OCDS-Revised: A Measure of Alcohol and Drug Urges With Outpatient Substance Abuse Clients.

Urges to use substances is an important construct in understanding the maintenance of substance use as well as relapse. There is a need to evaluate single instruments measuring global urges to use substances (including alcohol). The Obsessive Compulsive Drinking Scale (OCDS; R. F. Anton, D. H. Moak, & P. Latham, 1995) was revised and tested as a single measure of urges to use substances. Participants were 252 adults entering outpatient substance abuse treatment. Results suggest that the revised scale (OCDS-R) primarily assesses 1 global factor for urges to use substances. In addition, strong support was found for the reliability and concurrent validity of the OCDS-R, although results for its predictive validity were mixed. The OCDS-R is a brief, psychometrically sound self-report instrument that has applicability within clinical and research settings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)