Hamiltonian analysis of non-projectable modified F(R) Ho\v{r}ava-Lifshitz gravity

We study a version of the recently proposed modified $F(R)$ Ho\v{r}ava-Lifshitz gravity that abandons the projectability condition of the lapse variable. We discovered that the projectable version of this theory has a consistent Hamiltonian structure, and that the theory has interesting cosmological solutions which can describe the eras of accelerated expansion of the universe in a unified manner. The usual Ho\v{r}ava-Lifshitz gravity is a special case of our theory. Hamiltonian analysis of the non-projectable theory, however, shows that this theory has serious problems. These problems are compared with those found in the original Ho\v{r}ava-Lifshitz gravity. A general observation on the structure of the Poisson bracket of Hamiltonian constraints in all theories of the Ho\v{r}ava-Lifshitz type is made: in the resulting tertiary constraint the highest order spatial derivative of the lapse $N$ is always of uneven order. Since the vanishing of the lapse (N=0) is required by the preservation of the Hamiltonian constraints under time evolution, we conclude that the non-projectable version of the theory is physically inconsistent.Comment: LaTeX 18 pages. v3: Some errors have been correcte

Nitrate, nitrite and microbial denitrification in drinking water from Ozun village (Covasna County, Romania) and the association between changes during water storage

Severe groundwater contamination affects drinking water quality in many vulnerable zones across Romania. Ingestion of high levels of nitrate and nitrite can lead to the emergence of compounds with major toxicological effects. The present study was aimed to assess nitrate and nitrite concentrations in parallel with the activity of denitrifying bacteria, in different groundwater sources from Ozun village, Covasna County. Natural denitrification potential based on local microbiota was investigated during water storage for one month. Results indicate that tap water supplied from the public system complies with drinking water criteria, but most domestic wells are not safe. Nitrate concentrations exceeded the maximum limit allowed for drinking water in most of the samples collected from dug wells, while nitrite ions occurred within the mandatory limit. Denitrifying bacteria were detected in all groundwater samples, with the exception of one well. Regrowth of denitrifying bacteria was observed during water storage, but significant reduction of nitrate, nitrite or their sum of ratio did not occurred as a general rule. The association between percentage changes in bacterial counts, nitrate and nitrite concentrations was not statistically significant. In conclusion, enhancing the bioremediation potential of local microbiota by groundwater storage at household level is not an efficient strategy for nitrate/ nitrite removal. Raduly et Farkas (PDF

RESEARCH ON HUMAN RESOURCES MOTIVATION AND SATISFACTION

Many research studies on the human resources performance of the educational system have proved that pupils/students’ educational success depends, to a high degree, on the level of human resource motivation, as well as on their degree of professional satisfaction. Teachers’ who show a high level of motivation, both intrinsic and extrinsic, invest more into their activity, are more creative and more efficient in problem solving. The paper debates the results of an empirical study regarding the influence of pre-university teachers’ motivation and satisfaction regarding the general work conditions on their work performance by measuring the present motivation and satisfaction level. Furthermore, the determinant factors of their satisfaction with the work place are determined and analyzed. Finally, based on the statistical data process we will conclude and debate on the research hypothesis validation and the empirical model related to motivation – satisfaction – performance interdependences

Screening for phenotypic and genotypic resistance to antibiotics in Gram positive pathogens

Gram positive bacteria such as methicillin resistant Staphylococcus aureus, vancomycin resistant enterococci or multidrug resistant Streptococcus spp. are increasingly involved in severe infections with serious clinical consequences. The aim of this study is to investigate phenotypic and genotypic resistance traits in Gram positive pathogens isolated from clinical specimens in Cluj-Napoca, Romania. A total number of 31 Enterococcus spp., Staphylococcus spp. and Streptococcus spp. strains were subjected to antimicrobial susceptibility testing by disc diffusion, while the carriage of 26 antibiotic resistance genes and of class 1 integron was assessed by PCR. Bacterial pathogens included in this study were mostly susceptible to folate pathway inhibitors (100%), oxazolidinones (97%), fosfomycins (93%) and glycopeptides (92%). Enterococci, staphylococci and streptococci displayed high levels of phenotypic resistance to penicillins, tetracyclines and macrolides, a percentage of 42% being multidrug resistant. The strains under this study proved to be able to produce β-lactamase enzymes encoded by the TEM-1 gene and aminoglycoside modifying enzymes due to the carriage of aac(6’)-Ie-aph(2”) gene, to possess ribosomal protection mechanisms for macrolide and tetracycline resistance associated with ermB, ermC and tet(M) genes and to bear efflux genes tet(A), tet(B), tet(C) ant tet(L). Class 1 integron integrase was detected in 16% of the isolates, but no significant correlations were found between the carriage of intI1 gene and the phenotypic or genotypic resistance among the Gram positive pathogens investigated. Farcas et al (PDF

Correlation between CRISPR Loci Diversity in Three Enterobacterial Taxa

CRISPR-Cas is an adaptive immunity system of prokaryotes, composed of CRISPR arrays and the associated proteins. The successive addition of spacer sequences in the CRISPR array has made the system a valuable molecular marker, with multiple applications. Due to the high degree of polymorphism of the CRISPR loci, their comparison in bacteria from various sources may provide insights into the evolution and spread of the CRISPR-Cas systems. The aim of this study was to establish a correlation between the enterobacterial CRISPR loci, the sequence of direct repeats (DR), and the number of spacer units, along with the geographical origin and collection source. For this purpose, 3474 genomes containing CRISPR loci from the CRISPRCasdb of Salmonella enterica, Escherichia coli, and Klebsiella pneumoniae were analyzed, and the information regarding the isolates was recorded from the NCBI database. The most prevalent was the I-E CRISPR-Cas system in all three studied taxa. E. coli also presents the I-F type, but in a much lesser percentage. The systems found in K. pneumoniae can be classified into I-E and I-E*. The I-E and I-F systems have two CRISPR loci, while I-E* has only one locus upstream of the Cas cluster. PCR primers have been developed in this study for each CRISPR locus. Distinct clustering was not evident, but statistically significant relationships occurred between the different CRISPR loci and the number of spacer units. For each of the queried taxa, the number of spacers was significantly different (p < 0.01) by origin (Africa, Asia, Australia and Oceania, Europe, North America, and South America) but was not linked to the isolation source type (human, animal, plant, food, or laboratory strains)

Preliminary data regarding genetic diversity of several endangered and endemic Dianthus species from Romania generated by RAPD markers

Conservation of endangered and endemic species of Dianhtus from Romania, requires the investigation of genetic polymorphism in the populations. Preliminary data were obtained by molecular characterization using RAPD markers. DNA amplification with the 9 RAPD primers of the individuals belonging to different populations of D. callizonus, D. giganteus ssp. banaticus, D. glacialis ssp. gelidus, D. henteri, D. nardiformis, D. pratensis ssp. racovitzae, D. spiculifolius and D. tenuifolius revealed low level of polymorphism within and between populations. Several polymorphic RAPD markers were identified being useful for investigation of genetic diversity. Out the 9 primers studied by us, only the primer OPB-07 ensured amplification in all species and primers OPA-13, OPE-04 and 1225 showed positive results in most of the species. The primers 4A-26 and 4A-27 ensured amplification only in D. spiculifolius and the primers 4A-23 and OPM-18 gave no results in none of the species. Butiuc-Keul et al (PDF

Molecular Typing Reveals Environmental Dispersion of Antibiotic-Resistant Enterococci under Anthropogenic Pressure

As a consequence of global demographic challenges, both the artificial and the natural environment are increasingly impacted by contaminants of emerging concern, such as bacterial pathogens and their antibiotic resistance genes (ARGs). The aim of this study was to determine the extent to which anthropogenic contamination contributes to the spread of antibiotic resistant enterococci in aquatic compartments and to explore genetic relationships among Enterococcus strains. Antimicrobial susceptibility testing (ampicillin, imipenem, norfloxacin, gentamycin, vancomycin, erythromycin, tetracycline, trimethoprim-sulfamethoxazole) of 574 isolates showed different rates of phenotypic resistance in bacteria from wastewaters (91.9–94.4%), hospital effluents (73.9%), surface waters (8.2–55.3%) and groundwater (35.1–59.1%). The level of multidrug resistance reached 44.6% in enterococci from hospital effluents. In all samples, except for hospital sewage, the predominant species were E. faecium and E. faecalis. In addition, E. avium, E. durans, E. gallinarum, E. aquimarinus and E. casseliflavus were identified. Enterococcus faecium strains carried the greatest variety of ARGs (blaTEM-1, aac(6′)-Ie-aph(2″), aac(6′)-Im, vanA, vanB, ermB, mefA, tetB, tetC, tetL, tetM, sul1), while E. avium displayed the highest ARG frequency. Molecular typing using the ERIC2 primer revealed substantial genetic heterogeneity, but also clusters of enterococci from different aquatic compartments. Enterococcal migration under anthropogenic pressure leads to the dispersion of clinically relevant strains into the natural environment and water resources. In conclusion, ERIC-PCR fingerprinting in conjunction with ARG profiling is a useful tool for the molecular typing of clinical and environmental Enterococcus species. These results underline the need of safeguarding water quality as a strategy to limit the expansion and progression of the impending antibiotic-resistance crisis

Molecular Characterization of <i>Prunus</i> Cultivars from Romania by Microsatellite Markers

In Romania, Prunus species have great economic and social importance. With the introduction of new cultivars arises the need to preserve and characterize the local Prunus germplasm. Thus, a set of 24 polymorphic SSRs were selected for the overall characterization, including 10 peach, 11 apricot and 5 nectarine cultivars. The average number of alleles per locus (Na = 1.958), in addition to overall observed (Ho = 0.299) and expected heterozygosity (He = 0.286) were lower or comparable to those reported in similar studies, probably explained by the smaller number of analyzed cultivars restricted to a smaller geographic area. Among 26 genotypes a total of 101 alleles were identified, of which 46 alleles were in peach, 55 in apricot and 40 in nectarine, respectively. Six alleles from six loci (CPPCT-030, Pchgms-003, Pchgms-004, Pchgms-010, UDP97-401, UDP98-405) were common to all taxonomic groups. The most informative loci were BPPCT-025, Pchgms-021 and UDP96-001 in peach; BPPCT-025, BPPCT-001 and UDP96-001 in nectarine; and BPPCT-002, BPPCT-025, Pchgms-004, Pchgms-020 and Pchgms-021 in apricot. Clustering and genetic similarity analysis indicated that the degree of interspecific divergence in peach and nectarine cultivars was less than that in peach and apricot. These results will be useful to prevent confusion between cultivars, to improve breeding strategies and to benefit the management of Prunus cultivars bred in Romania