Selective excitation of homogeneous spectral lines

It is possible, for homogeneously broadened lines, to excite selectively the response signals, which are orders of magnitude narrower than the original lines. The new type of echo, which allows detecting such signals, and the formalism, useful for understanding the phenomenon, as well as the experimental examples from NMR spectroscopy are presented.Comment: 19 pages, 8 figure

Dynamics of Neural Networks with Continuous Attractors

We investigate the dynamics of continuous attractor neural networks (CANNs). Due to the translational invariance of their neuronal interactions, CANNs can hold a continuous family of stationary states. We systematically explore how their neutral stability facilitates the tracking performance of a CANN, which is believed to have wide applications in brain functions. We develop a perturbative approach that utilizes the dominant movement of the network stationary states in the state space. We quantify the distortions of the bump shape during tracking, and study their effects on the tracking performance. Results are obtained on the maximum speed for a moving stimulus to be trackable, and the reaction time to catch up an abrupt change in stimulus.Comment: 6 pages, 7 figures with 4 caption

A KINEMATIC ANALYSIS OF TRUNK ABILITY IN WHEELCHAIR FENCING: A PILOT STUDY

The purpose of this study was to explore the trunk ability differences between category A and B participants in wheelchair fencing. The result showed that category B participants might perform similar performance as category A participants in maximum lunge velocity, maximum lunge angle and maximum fast return velocity. This result may provide information to International Wheelchair Fencing Committee (IWFC) for the need of research on Wheelchair Fencing Classification (WFC) to clarify the differences between these two categories of participants

A KINEMATIC ANALYSIS OF TRUNK ABILITY IN WHEELCHAIR FENCING: A PILOT STUDY

The purpose of this study was to explore the trunk ability differences between category A and B participants in wheelchair fencing. The result showed that category B participants might perform similar performance as category A participants in maximum lunge velocity, maximum lunge angle and maximum fast return velocity. This result may provide information to International Wheelchair Fencing Committee (IWFC) for the need of research on Wheelchair Fencing Classification (WFC) to clarify the differences between these two categories of participants

Origin of lymph node-derived lymphocytes in human hepatic allografts

Hepatic allograft-derived lymph nodes were examined in the post-transplant period on order to determine the origin of lymphocytes and structural elements of the lymph node. Histologic assessment and immunohistochemical studies verified that T-cell infiltration of donor lymph nodes by recipient-derived lymphocytes occurred early in the post-transplant period. These T cells bore T-cell activation markers, e.g. TAC receptor and HLA-DR antigens. In addition, functional analysis demonstrated alloreactive T cells in secondary proliferation assays. The pattern of alloreactivity in these assays was dependent upon the phenotypic make-up (and therefore origin) of the lymphocytes within the lymph node. A gradual shift in predominance of donor-derived lymphocytes to recipient-derived lymphocytes occurred, but even late in the post-transplant course the stromal elements and a residium of lymphocytes within the lymph nodes continued to bear donor HLA antigens. The possible role of these 'passenger' lymphocytes in allograft immunity is discussed

Application of positive matrix factorization in estimating aerosol secondary organic carbon in Hong Kong and its relationship with secondary sulfate

International audienceSecondary organic carbon (SOC) is often a significant portion of organic carbon (OC) in ambient particulate matter (PM). The levels and seasonal patterns of SOC in Hong Kong were examined using more than 2000 PM10 measurements made over a 4.5-year period (1998?2002) in a network of ten air quality monitoring stations. The positive matrix factorization (PMF) model was used to analyze this large data set for source identification and apportioning. SOC was subsequently estimated to be the sum of OC present in the secondary sources, i.e., secondary sulfate, secondary nitrate, and secondary organic aerosol. The annual average SOC as estimated by the PMF method was 4.25 ?g C/m3 while the summer average was 1.66 ?g C/m3 and the winter average was 7.05 ?g C/m3. In comparison, the method that uses EC as a tracer for primary carbonaceous aerosol sources to derive SOC overestimated SOC by 70?212% for the summer samples and by 4?43% for the winter samples. The overestimation by the EC tracer method resulted from the inability of obtaining a single OC/EC ratio that represented a mixture of primary sources varying in time and space. We found that SOC and secondary sulfate had synchronous seasonal variation and were correlated in individual seasons, suggesting common factors that control their formation. Additionally, the presence of SOC was found to be enhanced more than that of secondary sulfate in the winter. We postulate this to be a combined result of favorable partitioning of semivolatile SOC species in the particle phase and more abundant SOC precursors in the winter

Three years clinical experience with intestinal transplantation

BACKGROUND: After the successful evolution of hepatic transplantation during the last decade, small bowel and multivisceral transplantation remains the sole elusive achievement for the next era of transplant surgeons. Until recently, and for the last thirty years, the results of the sporadic attempts of intestinal transplantation worldwide were discouraging because of unsatisfactory graft and patient survival. The experimental and clinical demonstration of the superior therapeutic efficacy of FK 506, a new immunosuppressive drug, ushered in the current era of small bowel and multivisceral transplantation with initial promising results. STUDY DESIGN: Forty-three consecutive patients with short bowel syndrome, intestinal insufficiency, or malignant tumors with or without associated liver disease, were given intestinal (n=15), hepatic and intestinal (n=21), or multivisceral allografts that contained four or more organs (n=7). Treatment was with FK 506 based immunosuppression. The ascending and right transverse colon were included with the small intestine in 13 of the 43 grafts, almost evenly distributed between the three groups. RESULTS: After six to 39 months, 30 of the 43 patients are alive, 29 bearing grafts. The most rapid convalescence and resumption of diet, as well as the highest three month patient survival (100 percent) and graft survival (88 percent) were with the isolated intestinal procedure. However, this advantage was slowly eroded during the first two postoperative years, in part because the isolated intestine was more prone to rejection. By the end of this time, the best survival rate (86 percent) was with the multivisceral procedure. With all three operations, most of the patients were able to resume diet and discontinue parenteral alimentation, and in the best instances, the quality of life approached normal. However, the surveillance and intensity of care required for these patients for the first year, and in most instances thereafter, was very high, being far more than required for patients having transplants of the liver, kidney or heart. CONCLUSIONS: Although intestinal transplantation has gone through the feasibility phase, strategies will be required to increase its practicality. One possibility is to combine intestinal transplantation with contemporaneous autologous bone marrow transplantation

Application of positive matrix factorization in estimating aerosol secondary organic carbon in Hong Kong and insights into the formation mechanisms

International audienceSecondary organic carbon (SOC) is often a significant portion of organic carbon (OC) in ambient particulate matter (PM). The levels and seasonal patterns of SOC in Hong Kong were examined using more than 2000 PM10 measurements made over a 4.5-year period (1998?2002) in a network of ten air quality monitoring stations. The positive matrix factorization (PMF) model was used to analyze this large data set for source identification and apportioning. SOC was subsequently estimated to be the sum of OC present in the secondary sources, i.e., secondary sulfate, secondary nitrate, and secondary organic aerosol. The annual average SOC as estimated by the PMF method was 4.25 µg C/m3 while the summer average was 1.66 µg C/m3 and the winter average was 7.05 µg C/m3. In comparison, the method that uses EC as a tracer for primary carbonaceous aerosol sources to derive SOC overestimated SOC by 70?212% for the summer samples and by 4?43% for the winter samples. The overestimation by the EC tracer method resulted from the inability of obtaining a single OC/EC ratio that represented a mixture of primary sources varying in time and space. We found that SOC and secondary sulfate had synchronous seasonal variation and were correlated in individual seasons, suggesting common factors that control their formation. Considering the well-established fact that both gas phase oxidation and in-cloud processing are important formation pathways for sulfate, the synchronicity of SOC and sulfate suggests that in-cloud pathways are also important for SOC formation. Additionally, the presence of SOC was found to be enhanced more than that of secondary sulfate in the winter. We postulate this to be a combined result of favorable partitioning of semivolatile SOC species in the particle phase and more abundant SOC precursors in the winter

Abdominal multivisceral transplantation

Under FK506-based immunosuppression, 13 abdominal multivisceral transplantations were performed in 6 children and 7 adults. Of the 13 recipients, 7 (53.8%) are alive and well with functioning grafts after 9 to 31 months. Six recipients died: Three from PTLD, one from rejection, one from sepsis, and one from respiratory failure. In addition to rejection, postoperative complications occurring in more than isolated cases included PTLD (n=6), abdominal abscess formation (n=5), pancreatitis (n=3), and ampullary dysfunction (n=2). In addition, infection by enteric microorganisms was common during the early postoperative period. Currently, all 7 survivors are on an oral diet and have normal liver function. Two recipients (one insulin-dependent) require antidiabetes treatment, in one case following distal pancreatectomy and in the other after two episodes of pancreatic rejection. Thus, abdominal multivisceral transplantation is a difficult but feasible operation that demands complex and prolonged posttransplantation management. It is not yet ready for application and awaits a better strategy of immune modulation. © 1995 by Williams & Wilkins