Measurement of mode times of flight in multimode fibers by an interferometric method using polychromatic light: theoretical approach and experimental results

The propagation of several modes in an optical fiber is not easy to study. The experiment that we propose permits us to measure the difference in time propagation between two successive modes of a multimode fiber. The same laser beam is coupled into the fiber to be tested and into the reference single-mode fiber. The correlation of output electric fields of the modes propagated by each fiber is realized by an interferometric system.     

Regulatory mechanisms in maintenance and modulation of transmembrane lipid asymmetry: pathophysiological implications

The two leaflets of the plasma membrane of eukaryotic cells differ in lipid composition: the outer leaflet comprises mainly neutral choline containing phospholipids, whereas the aminophospholipids reside almost exclusively in the cytoplasmic leaflet. The importance of transmembrane lipid asymmetry may be judged from the fact that the cell invests energy to maintain this situation for which at least two regulatory mechanisms are held responsible. A translocase, selective for aminophospholipids, acts as an ATP-dependent pump for rapid inward movement of phosphatidylserine (PS) and phosphatidylethanolamine; in addition, a non-selective, but also ATP-dependent pump causes outward movement of phospholipids, be it at a much lower rate compared to the inward transport by the aminophospholipid translocase. These two systems, acting in concert, are thought to be the main players in the maintenance of a dynamic equilibrium of the phospholipids over both membrane leaflets. Dissipation of membrane lipid asymmetry can be elicited in different cell types under a variety of conditions; in particular, platelets upon activation rapidly lose their normal plasma membrane lipid distribution, but also in other blood cells, lipid asymmetry can be lost, be it at a much lower rate and extent than in platelets. A putative protein, referred to as "scramblase' has been described, which requires the continuous presence of elevated intracellular Ca(2+)-levels, to allow a rapid, non-selective and bidirectional transbilayer movement of phospholipids. Although scrambling of lipids does not require ATP as such, preliminary studies suggest the possible involvement of one or more phosphorylated proteins. The most prominent consequence of the loss of phospholipid asymmetry is exposure of PS in the outer leaflet of the plasma membrane. Surface-exposed PS serves several important physiological functions: it promotes assembly of enzyme complexes of the coagulation cascade, it forms a signal for cell-cell recognition, which is important for cell scavenging processes. Surface-exposure of PS is an early phenomenon of apoptosis and appears to be involved in efficient removal of these cells. In addition, PS in the outer leaflet of cells is thought to play a role in cell fusion processes. It may be clear from the foregoing, that the amount of PS present at the cell surface needs to be tightly controlled, and that an impairment of this process leads to either excessive- or diminished exposition of PS which may have several pathophysiological consequences.     

Evaluation of two nonculture antigen tests and three serotests for detection of anti-chlamydial antibodies in the diagnosis of ocular chlamydial infections

BACKGROUND: Diagnosis of chlamydial conjuctivitis is difficult in chronic diseases because chlamydial elementary bodies are mostly undetectable in conjunctival scrapings by cell culture. We therefore compared two nonculture antigen tests and three different serotests for anti-chlamydial antibodies with McCoy cell culture, the "gold standard" of chlamydial diagnosis. Conjunctival scrapings and serum samples of 93 patients attending the outpatient eye clinic in Graz because of chronic follicular conjunctivitis were tested. METHODS: A total of 558 conjunctival scrapings and 93 serum samples were investigated. Chlamydial antigen detection was done by McCoy cell culture, polymerase chain reaction (PCR; Amplicor, Roche), and direct immunofluorescence assay (DFA; Microtrak, Syva). Antichlamydial IgA and IgG antibodies in the sera were detected by an immunoperoxidase assay (IPAzyme, Savyon) and two different enzyme-linked immunosorbent assays (SeroELISA, Savyon and rELISA, medac). RESULTS: Cell culture and PCR yielded identical results. The positivity rate for chlamydial conjunctivitis was 8.6% (8 of 93 patients). PCR proved most sensitive and most specific. IPAzyme was 75% sensitive for IgA and 100% for IgG; SeroELISA and rELISA were less sensitive. IPAzyme was 81% specific for IgA and 47.3% for IgG. SeroELISA and rELISA were less specific for IgA, but more specific for IgG. Post-test likelihood of disease was greatest in IPAzyme. CONCLUSIONS: PCR proved to be a good alternative to cell culture; DFA is useful for quick diagnosis. Genus-specific serotests cannot compete with chlamydial antigen detection. They differ in sensitivity and specificity because of the antigen type they present. They are still of only supportive value in cases where chlamydial antigen detection is not possible. Recently introduced species-specific antibody tests should be of greater value.     

Structure-function studies of p38 mitogen-activated protein kinase. Loop 12 influences substrate specificity and autophosphorylation, but not upstream kinase selection

Several mitogen-activated protein kinase (MAPK) cascades have been identified in eukaryotic cells. The activation of MAPKs is carried out by distinct MAPK kinases (MEKs or MKKs), and individual MAPKs have different substrate preferences. Here we have examined how amino acid sequences encompassing the dual phosphorylation motif located in the loop 12 linker (L12) between kinase subdomains VII and VIII and the length and amino acid sequence of L12 influence autophosphorylation, substrate specificity, and upstream kinase selectivity for the MAPK p38. Conversion of L12 of p38 to an "ERK-like" structure was accomplished in several ways: (i) by replacing glycine with glutamate in the dual phosphorylation site, (ii) by placing a six-amino acid sequence present in L12 of ERK (but absent in p38) into p38, and (iii) by mutations of amino acid residues in loop 12. Two predominant effects were noted: (i) the Xaa residue in the dual phosphorylation motif Thr-Xaa-Tyr as well as the length of L12 influence p38 substrate specificity, and (ii) the length of L12 plays a major role in controlling autophosphorylation. In contrast, these modifications do not result in any change in the selection of p38 by individual MAPK kinases.     

Meningeal carcinomatosis in patient with esophagus adenocarcinoma

We assessed the practicality of using the Short Michigan Alcoholism Screening Test (SMAST) and the Alcohol Use Disorders Identification Test (AUDIT) in screening adolescents for alcoholism in a primary care setting. In addition, we sought to determine the prevalence of alcohol use among adolescents, 16-21 years of age, presenting to a private Family Medicine practice for medical care. A consecutive sample of 67 subjects presenting for medical care were asked to complete the SMAST and AUDIT questionnaires. Overall, 52 (78%) of the questionnaires were returned with complete data. Of the 52 patients, 25 (48%) admitted to drinking. Using a "positive" score on either the SMAST or AUDIT as a positive test for alcohol use yielded a sensitivity of 40% and a predictive value positive of 100%. Using a "negative" score on both the SMAST and AUDIT as a negative test for alcohol use yielded a specificity of 100% and a predictive value negative of 64%. Although alcohol use was relatively common considering the age group, using the SMAST and AUDIT to screen for alcoholism is labor intensive and is not practical in this situation. Because patients appeared to misinterpret some questions and were often accompanied to the office by their parents, their answers may not be valid. History of alcoholism taken upon typical office examination and relevant advice appears to be a better alternative to the use of questionnaires in determining the prevalence of alcohol use in this age group.     

Late epigastric incisional hernias following laparoscopic cholecystectomy

By the introduction of laparoscopic cholecystectomy a new "gold standard" procedure became a routinely performed operation in the field of biliary tract surgery. Thus, the incision related early and late complications are thought to diminish, especially the formation of incisional hernias. Five patients had been referred to our department suffering from chronic incisional hernias following laparoscopic cholecystectomy. All of the hernias were located to the site of the epigastric trocar. The contents of the hernias proved to be omentum. The documentation's of the laparoscopic cholecystectomies revealed the extraction of thick walled gallbladders that contain large stones, and the wounds through which the extraction was performed had not been closed. Taking into consideration the fact of the "Chimney Effect" caused by the desufflation of the pneumoperitoneum at the end of the laparoscopic operation, bowel or omentum can easily escape through the relatively large wound formed during the extraction of the gallbladder, resulting in the formation of incisional hernias. This can be avoided by the complete desufflation and the prompt closure of the wound.     

Observations on the miraxonal attraction exercised by sexually immature or adult Biomphalaria glabrata infected or not by Schistosoma mansoni

With CT imaging, the lumbar facet joints are well visualised and enlargement secondary to degeneration may be noted. We measured the cross-sectional area of the superior articular process of the L5 facet joint in 100 consecutive CT scans and in 71 patients, the L4 process was also measured. We found that the mean cross-sectional area was significantly larger at L5 than at L4. Patient age and sex had no significant effect on the size at either L4 or L5. A review of the radiological reports revealed that the 13 patients with degenerative facet joints and radiologically normal discs did not have significantly larger facet joints than the 35 patients with disc disease and radiologically normal facet joints. In conclusion, the term "facet joint hypertrophy" should not be used when osteoarthritic changes are noted on CT scan, because these joints are not significantly larger than normal facet joints.     

Visual data mining for crowd anomaly detection using artificial bacteria colony

This paper presents a novel method for global anomaly detection in crowded scenes. The optical flow of frames is used to extract the foreground of areas with people motions in the crowd in the form of layers. The optical flow between two frames generates one layer. The proposed method applies the metaheuristic of artificial bacteria colony as a robust algorithm to optimize the extracted layers. Artificial bacteria cover all regions of interest that have high movement between frames. The artificial bacteria colony adapts quickly to the most varied scenarios. Moreover, the algorithm has low sensibility to noise and to sudden changes in video lighting as captured by optical flow. The bacteria population of the colonies, its food storage and the colony’s centroid position regarding each optical flow layer, are used as input to train a Kohonen’s neural network. Once trained the network is able to detect specific events based on behavior patterns similarity, as produced by the bacteria colony during such events. Experiments are conducted on available public dataset. The achieved results show that the proposed method captures the dynamics of the crowd behavior successfully, revealing that the proposed scheme outperforms the available state-of-the-art algorithms for global anomaly detection.     

Shrinkage reduction and morphological characterization of PP reinforced with glass fiber and nanoclay using functionalized PP as compatibilizer

This work presents results of shrinkage and structure characteristics of reinforced PP using combinations of glass fiber and nanoclay with functionalized PP as compatibilizer during injection molding. Shrinkage, warpage and structure characteristics of clay-fiber reinforced nanocomposites using PP grafted with 2-[2- (Dimethylamino) ethoxy] ethanol (DMAE) to obtain PPgDMAE as compatibilizer, were analyzed. The glass fiber-nanoclay combinations decrease the PP shrinkage as well as the warpage tendency. Functionalized PP facilitates glass fiber and clay dispersion and intercalation. The crystallization temperature, Tc, increases slightly with respect to pure PP and the degree of crystallinity, Xc, was reduced with the clay content.