Statistical analysis of the fluctuating counts of fecal bacteria in the water of Lake Kinneret

Counts of E. coli, Enteroccoci and fecal coliforms in four sites around Lake Kinneret (The Sea of Galilee), collected every 2-4 weeks for about 5 years during 1995-2002 showed irregular fluctuations punctuated by aperiodic outbursts of variable magnitude. Because of the haphazard nature of fecal contamination and large intervals between successive counts, these patterns were described by probabilistic models, based on the truncated Laplace or Extreme Value distribution. Their applicability was tested by comparing the predicted frequencies of counts exceeding different levels calculated from the first half of each record with those actually observed in its second half. Despite the records imperfections and minor violations of the underlying models' assumptions, there was a reasonable agreement between the estimated and actual frequencies. This demonstrated that it is possible to translate the irregular fluctuation pattern into a set of probabilities of future high counts. In principle, such probabilities can be used to quantify the water's fecal contamination pattern and as a tool to assess the efficacy of preventive measures to reduce it.     

Diet effects on lipid composition,somatic growth potential,and survival of the benthic amphipod Diporeia spp.

The benthic amphipod Diporeia represents a crucial trophic link that conveys vital nutrients and energy to predators at higher trophic levels. The current decline of Diporeia populations, mostly in the North American Great Lakes, may, in part, be related to concurrent declines in food quantity and/or quality. We hypothesized that somatic growth and survival of Diporeia would be positively related to dietary supply and subsequent retention of polyunsaturated fatty acids (PUFA); a class of chemicals known to affect diet quality. We examined how different algal PUFA concentrations in; a) Ankistrodesmus falcatus (Chlorophyta), b) a naturally occurring diatom assemblage from Lake Ontario, c) a non-toxic strain of Microcystis aeruginosa (Cyanophyta), and, d) fasting for 30 d, affected PUFA concentrations, somatic growth, and survival of Diporeia. Total PUFA concentrations were significantly higher in A. falcatus than in diatoms and Microcystis, but only diatoms contained considerable amounts of eicosapentaenoic (EPA) and docosahexaenoic acid (DHA). EPA, DHA, and arachidonic acid (ARA) were highly retained in Diporeia even in the absence of dietary supply with ARA being the most efficiently bioaccumulated PUFA. Survivorship of Diporeia ranged from 60% (diatom-fed), 68% (A. falcatus-fed), to 70% (fasting treatment), but was 0% in the M. aeruginosa diet treatment. Nucleic acid ratios (RNA:DNA), commonly used as proxies for somatic growth potential, were highest in Diporeia feeding on diatoms and lowest in fasting animals. We conclude that overall condition of Diporeia improved with dietary access to EPA and DHA, but survival was not related to this food quantity and/or quality.     

Toxins and Biologically Active Secondary Metabolites of Microcystis sp. isolated from Lake Kinneret

For many years cyanobacteria were considered a minor, negligible component of the phytoplankton population in Lake Kinneret (Sea of Galilee, Israel). However, during the last decade several new species invaded the lake and other, more common species were present more frequently and in higher concentrations. Recently, we isolated two Microcystis sp. strains from Lake Kinneret. Both produced an array of hepatotoxic microcystins. In a bioassay-guided study we identified in exudates of one of the Microcystis strains (MB-K) that allelopathic activity was attributed to a novel metabolite, microcarbonin A ( 1 ). Subsequently, two other novel metabolites, micropeptin KT946 ( 2 ) and anabaenopeptin KT864 ( 3 ), were isolated from the hydrophilic extract of the cultured (MB-K) strain, based on their protease inhibition activity. Homo- and heteronuclear-2D-NMR techniques, as well as HRMS, determined the gross structure of the three compounds. The relative and absolute stereochemistry of 2 and 3 was deduced from a combination of spectral data and Marfey's method for HPLC.     

An Investigation of Therapeutic Factors in Children's Groups.

The therapeutic factors present in children's groups were examined in this study for the first time. Using recorded interviews and the Group Counseling Helpful Impacts Scale (D. M. Kivlighan, K. D. Multon, & D. F. Brossat, 1996), the authors examined 4 categories: emotional awareness-insight, relationship-climate, other- versus self-focus, and problem identification-change. The sample consisted of 64 10-year-old boys and girls, in all-female or mixed-gender groups (n = 10). Results indicated that group relationship-climate was the therapeutic factor most frequently mentioned by the children and that problem identification-change was least appreciated. One difference was found between boys and girls, and one between all-female and mixed-gender groups. The discussion focuses on the importance and meaning of relationship-climate for children in group therapy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of Long-term Fasting on the Use of Fatty Acids as Trophic Markers in the Opossum Shrimp Mysis relicta—A Laboratory Study

Fatty acids are potential trophic markers to trace feeding relationships in aquatic ecosystems primarily because lipid reserves of organisms broadly reflect dietary sources of lipids and can therefore provide information on the availability of key fatty acids in the food web. However, the use of fatty acids for such applications may be constrained by the degree to which the fatty acid composition of organisms is obscured by factors other than straightforward uptake from the diet. Thus, we studied the effect of long-term fasting, under controlled laboratory conditions, on the lipid content and fatty acid composition of field-caught Mysis relicta. Periods of 3 to 6 weeks are required to induce clear effects of fasting in M. relicta. Relative proportions of docosahexaenoic acid (DHA; 22:6n-3) and arachidonic acid (ARA; 20:4n-6) increased with decreasing lipid contents during fasting. DHA proportions in the total fatty acid composition of fasting M. relicta were significantly higher in comparison to field-caught animals. M. relicta with high proportions of DHA (> 25%) and with low lipid contents (< 14% of dry weight) can be clearly identified as fasting animals. Such thresholds will help to improve the validity of fatty acids in trophic studies.     

Modification of interests through cognitive restructuring: Test of a theoretical model in preschool children.

Tested hypotheses derived from a theoretical model in which interests are a product of a person's modified cognitions of his or her perceived ability to perform, expected success in, and anticipated satisfaction from engaging in an activity. In a field experiment with 3 groups of preschool children (n?=?90), preferences for unfamiliar game activities were either cognitively restructured in line with the model's cognitive factors, rewarded through external reinforcers, or not manipulated. Participants were asked to rank their attraction to the activities before the manipulation, immediately after their first (restructured, rewarded, or unmanipulated) exposure to 4 activities, and 2 wks later. Results for both genders provided clear support for the argument of cognitive modification of interests. The differential development of interests is discussed from a cognitive-behavioral perspective and in relation to A. Bandura's self-efficacy theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Emotional availability and attachment representations in kibbutz infants and their mothers.

Three components of the attachment transmission model were examined in 48 kibbutz dyads from 2 kibbutz sleeping arrangements: communal and home-based. Concurrent assessments used the Strange Situation procedure (M. D. Ainsworth, M. C. Blehar, E. Waters, & S. Wall, 1978) for infants' attachment relations, the Adult Attachment Interview (C. George, N. Kaplan, & M. Main, 1985) for mothers' attachment representations, and the Emotional Availability Scales (Z. Biringen, J. L. Robinson, & R. N. Emde, 1993) for emotional availability in the dyads. Security of infants' attachment relations as well as autonomy of mothers' attachment representations were associated with higher emotional availability scores. In addition, significantly poorer emotional availability was found in dyads in which infants were insecurely attached and mothers were nonautonomous. Results also indicate that in the ecology of collective sleeping, the associations between the experience of emotional availability in the dyads and infants' and mothers' attachment may have been disrupted. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cleavage of an RNA Model Compound by an Arylmercury Complex

A water-soluble arylmercury complex has been synthesized, and its ability to catalyze the cleavage of the phosphodiester linkage of the RNA model compound adenylyl-3′,5′-(2′,3′-O-methyleneadenosine) has been assessed over a pH range of 3–8.5 and a catalyst concentration range of 0–7 mM. In the presence of 1 mM catalyst, the observed pH–rate profile featured a new pH-independent region between pH 6 and 7, the catalyzed reaction being as much as eight times faster than the background reaction. At pH 7, the acceleration increased linearly from three- to 17-fold upon increasing the catalyst concentration from 1 to 7 mM. The linear dependence indicates a relatively low affinity of the catalyst for the substrate and, hence, the potential for considerable improvement on tethering to an appropriate targeting group, such as an oligonucleotide.     

Effect of phonons on the ac conductance of molecular junctions

We theoretically examine the effect of a single phonon mode on the structure of the frequency dependence of the ac conductance of molecular junctions, in the linear response regime. The conductance is enhanced (suppressed) by the electron-phonon interaction when the chemical potential is below (above) the energy of the electronic state on the molecule.