893 resultados para system of geographic information
Resumo:
The practice of information systems (IS) outsourcing is widely established among organizations. Nonetheless, evidence suggests that organizations differ considerably in the extent to which they deploy IS outsourcing. This variation has motivated research into the determinants of the IS outsourcing decision. Most of this research is based on the assumption that a decision on the outsourcing of a particular IS function is made independently of other IS functions. This modular view ignores the systemic nature of the IS function, which posits that IS effectiveness depends on how the various IS functions work together effectively. This study proposes that systemic influences are important criteria in evaluating the outsourcing option. It further proposes that the recognition of systemic influences in outsourcing decisions is culturally sensitive. Specifically, we provide evidence that systemic effects are factored into the IS outsourcing decision differently in more individualist cultures than in collectivist ones. Our results of a survey of United States and German firms indicate that perceived in-house advantages in the systemic impact of an IS function are, indeed, a significant determinant of IS outsourcing in a moderately individualist country (i.e., Germany), whereas insignificant in a strongly individualist country (i.e., the United States). The country differences are even stronger with regard to perceived in-house advantages in the systemic view of IS professionals. In fact, the direction of this impact is reversed in the United States sample. Other IS outsourcing determinants that were included as controls, such as cost efficiency, did not show significant country differences.
Resumo:
Aeromonas salmonicida subsp. salmonicida is the etiologic agent of furunculosis, a frequent and significant disease of fisheries worldwide. The disease is largely controlled by commercial oil adjuvanted vaccines containing bacterins. However, the mechanisms leading to a protective immune response remain poorly understood. The type-three secretion system (T3SS) plays a central role in virulence of A. salmonicida subsp. salmonicida and thus may have an influence on the immune response of the host. The aim of this study was to evaluate the role of the T3SS antigens in mounting a protective immune response against furunculosis. Rainbow trout were intraperitoneally vaccinated in two independent experiments with bacterins prepared from a wild-type A. salmonicida strain and an isogenic strain carrying a deletion in the T3SS (ΔascV). Fish were challenged with the wt strain eight weeks after vaccination. In both trials, the survival rate of trout vaccinated with the ΔascV strain was significantly higher (23-28%) in comparison to the group vaccinated with the wt strain. High-throughput proteomics analysis of whole bacteria showed the ascV deletion in the mutant strain resulted in lower expression of all the components of the T3SS, several of which have a potential immunosuppressive activity. In a third experiment, fish were vaccinated with recombinant AcrV (homologous to the protective antigen LcrV of Yersinia) or S-layer protein VapA (control). AcrV vaccinated fish were not protected against a challenge while fish vaccinated with VapA were partially protected. The presence of T3SS proteins in the vaccine preparations decreased the level of protection against A. salmonicida infection and that AcrV was not a protective antigen. These results challenge the hypothesis that mounting specific antibodies against T3SS proteins should bring better protection to fish and demonstrate that further investigations are needed to better understand the mechanisms underlying effective immune responses against A. salmonicida infection.
Resumo:
Spiders, as all other arthropods, have an open circulatory system, and their body fluid, the hemolymph, freely moves between lymphatic vessels and the body cavities (see Wirkner and Huckstorf 2013). The hemolymph can be considered as a multifunctional organ, central for locomotion (Kropf 2013), respiration (Burmester 2013) and nutrition, and it amounts to approximately 20 % of a spider’s body weight. Any injury includes not only immediate hemolymph loss but also pathogen attacks and subsequent infections. Therefore spiders have to react to injuries in a combined manner to stop fluid loss and to defend against microbial invaders. This is achieved by an innate immune system which involves several host defence systems such as hemolymph coagulation and the production of a variety of defensive substances (Fukuzawa et al.2008). In spiders, the immune system is localised in hemocytes which are derived from the myocardium cells of the heart wall where they are produced as prohemocytes and from where they are released as different cell types into the hemolymph (Seitz 1972). They contribute to the defence against pathogens by phagocytosis, nodulation and encapsulation of invaders. The humoral response includes mechanisms which induce melanin production to destroy pathogens, a clotting cascade to stop hemolymph loss and the constitutive production of several types of antimicrobial peptides, which are stored in hemocyte granules and released into the hemolymph (Fukuzawa et al.2008) (Fig.7.1). The immune system of spiders is an innate immune system. It is hemolymph-based and characterised by a broad but not very particular specificity. Its advantage is a fast response within minutes to a few hours. This is in contrast to the adaptive immune system of vertebrates which can react to very specific pathogens, thus resulting in much more specific responses. Moreover, it creates an immunological memory during the lifetime of the species. The disadvantage is that it needs more time to react with antibody production, usually many hours to a few days, and needs to be built up during early ontogenesis.
Resumo:
The FsrABC system of Enterococcus faecalis controls the expression of gelatinase and a serine protease via a quorum-sensing mechanism, and recent studies suggest that the Fsr system may also regulate other genes important for virulence. To investigate the possibility that Fsr influences the expression of additional genes, we used transcriptional profiling, with microarrays based on the E. faecalis strain V583 sequence, to compare the E. faecalis strain OG1RF with its isogenic mutant, TX5266, an fsrB deletion mutant. We found that the presence of an intact fsrB influences expression of numerous genes throughout the growth phases tested, namely, late log to early stationary phase. In addition, the Fsr regulon is independent of the activity of the proteases, GelE and SprE, whose expression was confirmed to be activated at all three time points tested. While expression of some genes (i.e., ef1097 and ef0750 to -757, encoding hypothetical proteins) was activated in late log phase in OG1RF versus the fsrB deletion mutant, expression of ef1617 to -1634 (eut-pdu orthologues) was highly repressed by the presence of an intact Fsr at entry into stationary phase. This is the first time that Fsr has been characterized as a negative regulator. The newly recognized Fsr-regulated targets include other factors, besides gelatinase, described as important for biofilms (BopD), and genes predicted to encode the surface proteins EF0750 to -0757 and EF1097, along with proteins implicated in several metabolic pathways, indicating that the FsrABC system may be an important regulator in strain OG1RF, with both positive and negative effects.
Resumo:
The human colon tumor cell line, LS174T, has been shown to have four major components of the drug metabolizing system; cytochrome b$\sb5$ reductase, cytochrome b$\sb5$, cytochrome P450 reductase and cytochrome P450, by activity measurements, spectral studies and antibody cross-reactivity. Cytochrome P450IA1 is induced by benzanthracene in these cells as shown by activity with the specific substrate, ethoxyresorufin, cross-reactivity with rabbit antibodies to rat IA1, and by a hybridizing band on a Northern blot to a rat IA1 probe.^ Further, this system has proven responsive to various inducers and conditions of growth. The enzyme activities were found stable over limited cell passages with control values of 0.03 and 0.13 $\mu$mol/min/mg protein for NADPH and NADH cytochrome c (cyt c) reducing activity, 0.05 nmol cyt b$\sb5$ per milligram and 0.013 nmol cytochrome P450 per milligram of microsomal protein. Phenobarbital/hydrocortisone treatment showed a consistent, but not always significant increase in the NADPH and NADH cyt c reducing activity and benzanthracene treatment an increase in the NADH cyt c reducing activity. Delta-aminolevulinic acid (0.5mM) caused a significant decrease in the specific activity of all enzyme contents and activities tested.^ Finally, the cytochrome b$\sb5$ to cytochrome P450, by the coordinate induction of the cytochrome b$\sb5$ pathway by P450 inducers, by the high ratio of NADH to NADPH ethoxycoumarin deethylase activity in uninduced cell microsomes, and by the increase in NADH and NADPH ethoxycoumarin deethylase activity when the microsomes were treated with potassium cyanide, a desaturase inhibitor. ^
Resumo:
Motor-performance-enhancing effects of long final fixations before movement initiation – a phenomenon called Quiet Eye (QE) – have repeatedly been demonstrated. Drawing on the information-processing framework, it is assumed that the QE supports information processing revealed by the close link between QE duration and task demands concerning, in particular, response selection and movement parameterisation. However, the question remains whether the suggested mechanism also holds for processes referring to stimulus identification. Thus, in a series of two experiments, performance in a targeting task was tested as a function of experimentally manipulated visual processing demands as well as experimentally manipulated QE durations. The results support the suggested link because a performance-enhancing QE effect was found under increased visual processing demands only: Whereas QE duration did not affect performance as long as positional information was preserved (Experiment 1), in the full vs. no target visibility comparison, QE efficiency turned out to depend on information processing time as soon as the interval falls below a certain threshold (Experiment 2). Thus, the results rather contradict alternative, e.g., posture-based explanations of QE effects and support the assumption that the crucial mechanism behind the QE phenomenon is rooted in the cognitive domain.