The value of certification: an empirical assessment of the perceptions of end-users of local area networks

Abstract. Certification is one criterion that employers seek when hiring network professionals. Many employers assume a certified network professional is better able to manage networked resources than is a non-certified counterpart. Therefore, employers often offer a monetary premium to attract certified network professionals. By measuring end-user perceptions, the current study empirically assesses the popular industry assumption that certified network professionals are more adept managers of network resources than those individuals who are not certified network professionals. Analyses of a data derived from 299 end-users of 11 separate local area networks indicate no statistically significant difference exists between the capabilities of certified network professionals and non-certified network professionals.     

Flow reversal in the descending aorta: a guide to intraoperative assessment of aortic regurgitation with transesophageal echocardiography

This study assessed the value of biplane transesophageal echocardiographic assessment of diastolic flow reversal in the descending aorta as an alternative to Doppler color flow imaging in determining severity of aortic regurgitation. In 45 patients undergoing cardiac operations, the severity of aortic regurgitation was assessed by semiquantitative grading of the width of the Doppler color flow regurgitant jet relative to the left ventricular outflow tract, and the presence of diastolic flow reversal was assessed with pulsed-wave Doppler measurements at three sites in the descending aorta. In four patients, the diastolic flow reversal method was the only available form of assessment because of inadequate visualization of the left ventricular outflow tract beneath a mitral valve prosthesis. Diastolic flow reversal in the descending aorta was not observed in patients without aortic regurgitation and was always present in patients with severe aortic regurgitation. Aortic valve replacement successfully eliminated descending aortic flow reversal in all 19 patients in whom it was present before valve replacement. Identification of diastolic flow reversal at multiple sites in the descending aorta with biplane transesophageal echocardiography helps to confirm the presence of severe aortic regurgitation and can serve as an alternative method of assessment when visualization of the left ventricular outflow tract is impaired.     

The relationship between preparation convergence and retention of extracoronal retainers

PURPOSE: Although traditional ideal convergence (the sum of taper of the opposite sides) for crown preparation has been arbitrarily set at 4 degrees to 10 degrees, some believe absolute parallelism yields the highest retention. This study examined the relationship between the degree of convergence of a machined metal die and the retention of its casting. MATERIALS AND METHODS: The method used was that of cementing cast metal crowns onto full crown preparations on brass dies with varying convergence angles, and then recording the force required to remove the crowns from the dies in a vertical direction using a Tate-Emery Testing Machine and Load Indicator. RESULTS: It was found that retention (i.e., the force needed to remove the cemented castings from the die in their common long axis) increases from 0 degree convergence to peak between 6 degrees to 12 degrees convergence. It also seems that a critical film thickness does exist for optimum retention, and that film thicknesses smaller than the critical thickness may be responsible for the phenomenon that we have observed and directly related to the convergence angle itself. CONCLUSIONS: There seems to be experimental data supporting the use of traditionally taught convergence. Our study found that convergence angles between 6 degrees and 12 degrees seem to be optimum for tooth crown preparation when one plans to use zinc phosphate cement. Convergence angles of less than 6 degrees may not be desirable even if they can be clinically achieved. The results of our study indicate that a relationship exists between the convergence angle and the critical cement thickness that is necessary to realize the maximum strength properties of zinc phosphate cement.     

Use of Mono Mac 6 human monocytic cell line and J774 murine macrophage cell line in parallel antimycobacterial drug studies

The Mono Mac 6 (MM6) human monocytic cell line was evaluated with the established J774 murine macrophage cell line to ascertain its effectiveness in determining the intracellular activities of antimycobacterial drugs. Cells were infected with Mycobacterium tuberculosis H37Ra and treated with drug concentrations corresponding to the MICs, as well as to threefold higher than and threefold less than the MICs. Changes in CFU were compared after 7 days to determine significant differences between treated and nontreated groups. The results suggest that MM6 will make a useful model for testing the intracellular activities of antituberculosis drugs.     

Assessing declarative memory in schizophrenia using Wisconsin Card Sorting Test stimuli: the Paired Associate Recognition Test

The Paired Associate Recognition Test (PART) was developed to measure declarative memory using Wisconsin Card Sorting Test (WCST) stimuli, so that both tasks could be administered during functional neuroimaging to differentiate memory and executive function, and associated frontal and temporal lobe activation in schizophrenia. The current study was designed to compare PART and WCST performance in schizophrenic patients and to examine effects of medication and symptomatology. The PART, WCST, and standard declarative memory tasks were administered to 30 chronic schizophrenic patients and 30 matched healthy control subjects. Supporting task validity was the finding that patients were equally impaired on the PART and the WCST. Neuroleptics did not appear to affect performance. The effect of anticholinergic medication correlated negatively with WCST performance in a small subsample. Severity of schizophrenia-specific symptoms measured at intake on the Brief Psychiatric Rating Scale correlated negatively with performance on the WCST. These results support the application of the PART and WCST in future functional neuroimaging studies.     

The pattern of inflammation in rat sepsis due to enterotoxin-producing Staphylococcus aureus: a comparison with ischemia-reperfusion injury

Sepsis and trauma have similarities in their immunopathologic profiles. Both conditions can result in multi-system organ failure which is sometimes associated with cytokine generation and inflammatory cell activation. Furthermore, decreases in peripheral blood monocyte expression of HLA-DR have been noted in both human sepsis and trauma. However, the magnitude, onset, and time course of such stimuli are often difficult to ascertain in human studies. Thus, to study a more detailed in vivo immunologic profile in these conditions, rat models were employed. Our aim was to describe and analyze cytokine and peripheral blood immunophenotype patterns in bacterially induced rat sepsis and to compare this to rat ischemia-reperfusion injury. Sprague-Dawley rats underwent either bacterial injection with enterotoxin producing Staphylococcus aureus or hind limb ischemia/ reperfusion. Two bacterial doses which were either lethal or sublethal at 24-48 hours were utilized. Peripheral blood neutrophils and B-lymphocytes were studied for expression of beta-integrins (CD11b and CD11b/c) and I-A, respectively, using flow cytometry. Corresponding plasma levels of TNF alpha and interferon gamma were measured by ELISA. At 24 hr, a lethal bacterial lethal bacterial dose injection resulted in significantly higher levels of neutrophil CD11b/c expression (p < 0.005) compared with ischemia-reperfusion treatment. B-cell I-A expression was also higher in lethal sepsis. Gamma interferon levels were significantly higher in lethal sepsis compared with ischemia-reperfusion (p = 0.005). Studies over time showed that CD11b expression and interferon gamma were both more marked at 6 hr than at 24 hr in lethal sepsis. This pattern was not observed in sublethal sepsis or in ischemia-reperfusion. CD11b/c expression on the other hand remained elevated at comparable levels at 6 and 24 hr in lethal sepsis. B-cell I-A expression in ischemia-reperfusion and sublethal sepsis decreased at 24 hr compared with baseline. Lethal sepsis in rats injected with enterotoxin producing staphylococcus results in phasic alterations in neutrophil CD11b and plasma interferon levels prior to death. In analogy to the findings of monocyte decreases in DR expression observed in human trauma and sepsis, rat B-cell I-A expression showed decreases in sublethal sepsis as well as in ischemia-reperfusion injury. However, this was not observed in lethal sepsis. These findings have implications in understanding the immunologic/inflammatory changes observed in human sepsis and trauma.