LAN with collision avoidance : switch implementation and simulation study

Packet collisions and their resolution create a performance bottleneck in random access LANs. A hardware solution to this problem is to use collision avoidance switches. These switches allow the implementation of random access protocols without the penalty of collisions among packets. The simplest network based on collision avoidance is the Broadcast Star network, where all the stations are connected to a central switch. A more sophisticated architecture based on collision avoidance is the CAMB (Collision Avoidance Multiple Broadcast) Tree network, where concurrent broadcast is possible. This paper presents a design of a collision avoidance switch for the CAMB Tree using TTL devices. Simulation study exploring the performance of the Broadcast Star network in both synchronous and asynchronous operations is also presented in this paper

A new method of inducing selective brain hypothermia with saline perfusion into the subdural space: effects on transient cerebral ischemia in cats.

In this study, we tested brain surface cooling as a new method of inducing selective brain hypothermia, and evaluated its effects on focal cerebral ischemia using a cat model of transient middle cerebral artery (MCA) occlusion. Cats underwent 1 h of MCA occlusion followed by 5 h of reperfusion. Brain surface cooling was induced for 4 h during and after MCA occlusion in the hypothermia group, but not in the normothermia group. Brain surface cooling was performed using saline perfusion into the subdural space. Rectal temperature, brain surface temperature, and deep brain temperature were monitored, and regional cerebral blood flow (rCBF) and somatosensory evoked potential (SEP) were serially measured. After 5 h of reperfusion, water content was also measured. Although the rectal temperature was maintained at about 37 degrees C, the brain surface temperature decreased rapidly to 33 degrees C and was maintained at that temperature. For 3 h following reperfusion, the rCBF was lower in the hypothermia group than in the normothermia group. At 4 and 5 h after reperfusion, the recovery of SEP amplitude was significantly more enhanced in the hypothermia group than in the normothermia group. In the gray matter, the water content was significantly more diminished in the hypothermia group than in the normothermia group. These results demonstrate that our method is useful for protecting the ischemic brain from a transient MCA occlusion. This method may be adapted for neurological surgery.</p

Use of Procalcitonin in Patients on Chronic Hemodialysis: Procalcitonin Is Not Related with Increased Serum Calcitonin

Objectives. To investigate whether procalcitonin (PCT) could be useful for detecting bacterial infections in patients on hemodialysis (HD) and with increased calcitonin (CT). Methods. This prospective study included 42 males and 34 females on HD. The infection group consisted of 15 patients with proven bacterial infections; the other 61 patients were designated as the noninfection group. Serum C-reactive protein (CRP), interleukin (IL)-6, white blood cell (WBC) count, immature and total neutrophil (I/T) ratio, and CT were measured at the beginning of HD, and serum PCT levels at the beginning of HD and after HD. Results. The mean CT level in the both groups was apparently higher than that of nonchronic kidney disease. Significantly higher values between the infection and noninfection groups were seen for CRP, IL-6, WBC, I/T ratio, PCT, and CT. The PCT value of the area under the receiver operating characteristic curve was 0.921, which was significantly higher than the values for CRP (0.853; P < 0.01), IL-6 (0.739; P < 0.01), WBC (0.692; P < 0.01), and I/T ratio (0.584; P < 0.01). Conclusions. PCT was useful marker of bacterial infection in patients on HD and with increased CT. PCT levels should be determined before HD

Morphological features of lipid droplet transition during porcine oocyte fertilisation and early embryonic development to blastocyst in vivo and in vitro

Lipid content in mammalian oocytes or embryos differs among species, with bovine and porcine oocytes and embryos showing large cytoplasmic droplets. These droplets are considered to play important roles in energy metabolism during oocyte maturation, fertilisation and early embryonic development, and also in the freezing ability of oocytes or embryos; however, their detailed distribution or function is not well understood. In the present study, changes in the distribution and morphology of porcine lipid droplets during in vivo and in vitro fertilisation, in contrast to parthenogenetic oocyte activation, as well as during their development to blastocyst stage, were evaluated by transmission electron microscopy (TEM). The analysis of semi-thin and ultra-thin sections by TEM showed conspicuous, large, electron-dense lipid droplets, sometimes associated with mitochondrial aggregates in the oocytes, irrespective of whether the oocytes had been matured in vivo or in vitro. Immediately after sperm penetration, the electron density of the lipid droplets was lost in both the in vivo and in vitro oocytes, the reduction being most evident in the oocytes developed in vitro. Density was restored in the pronculear oocytes, fully in the in vivo specimens but only partially in the in vitro ones. The number and size of the droplets seemed, however, to have decreased. At 2- to 4-cell and blastocyst stages, the features of the lipid droplets were almost the same as those of pronuclear oocytes, showing a homogeneous or saturated density in the in vivo embryos but a marbled or partially saturated appearance in the in vitro embryos. In vitro matured oocytes undergoing parthenogenesis had lipid droplets that resembled those of fertilised oocytes until the pronuclear stage. Overall, results indicate variations in both the morphology and amount of cytoplasmic lipid droplets during porcine oocyte maturation, fertilisation and early embryo development as well as differences between in vivo and in vitro development, suggesting both different energy status during preimplantation development in pigs and substantial differences between in vitro and in vivo development.</p

Analysis of a city‐wide COVID‐19 prevention strategy for aged‐care facilities during third and fifth waves of COVID‐19 in Kyoto City, Kyoto, Japan

[Background] During the third wave of the COVID-19 pandemic at the end of 2020, clusters occurred frequently in aged-care facilities (ACFs), which put pressure on the medical field in Japan. Based on this experience, Kyoto University and Kyoto City collaborated to promote a citywide COVID-19 prevention strategy to prevent the spread of COVID-19 within ACFs. The aim of this study was to clarify the effect of the prevention strategy among ACFs in Kyoto City during the third and fifth waves of the pandemic. [Methods] During the study period, the following measures were adopted as the prevention strategy in all ACFs: (1) active polymerase chain reaction (PCR) mass testing and facility-wide testing when a single case was identified, (2) implementation of strategies to prevent transmission within a facility, and (3) vaccination program for ACFs. [Results] Of the 1, 144 facilities subjected to the mass testing, 71.0% participated in the whole program including active PCR testing. The remainder participated in the rest of the programs. The prevalence of ACF-related COVID-19 cases among total COVID-19 cases in Kyoto City decreased from 7.9% in the third wave to 4.1% in the fourth wave and 2.1% in the fifth wave. The incidence of clusters and proportion of severe elderly cases also decreased during the study period. [Conclusions] A city-wide multidisciplinary effort including PCR mass testing and a vaccination program in cooperation with a university and local administrative office successfully reduced the clusters and transmission in ACFs in Kyoto City, Japan

The Influence of Environment on the Star Formation Rates of Galaxies

We have used a sample of 15749 galaxies taken from the Las Campanas Redshift Survey to investigate the effects of environment on the rate of star formation (SFR) in galaxies. The size and homogeneity of this data set allows us to sample, for the first time, the entire range of galactic environment, from the voids to the clusters, in a uniform manner, thus, we could decouple the local galaxy density from the membership in associations. This decoupling is very crucial for constraining the physical processes responsible for the environmental dependencies of SFR. On the other hand, the use of an automatically-measured concentration index (C), rather than Hubble type, allows us to cleanly separate the morphological component from the SFR vs. environment relationship. We find that cluster galaxies exhibit lower SFR for the same C than field galaxies, while a further division of clusters by `richness' reveals a new possible excitation of `starbursts' in poor clusters. Meanwhile, a more general environmental investigation reveals that the SFR of a given C shows a continuous correlation with the local density. Interestingly, this trend is also observed both inside and outside of clusters, implying that physical processes responsible for this correlation might not be intrinsic to the cluster environment. On the other hand, galaxies with differing levels of SFR appear to respond differently to the local density. Low levels of SFR are more sensitive to environment inside than outside of clusters. In contrast, high levels of SFR, identified as ``starbursts'', are as sensitive to local density in the field as in clusters. We conclude that at least two separate processes are responsible for the environmental sensitivity of the SFR.Comment: 25 pages, 10 figures, submitted to Ap

Clonal Expansion of Multidrug-Resistant <i>Streptococcus dysgalactiae</i> Subspecies <i>equisimilis</i> Causing Bacteremia, Japan, 2005–2021

Incidence of Streptococcus dysgalactiae subspecies equisimilis (SDSE) bacteremia is increasing in the Kyoto-Shiga region of Japan. We retrospectively analyzed clinical features of SDSE bacteremia and conducted comparative genomic analyses of isolates collected from 146 bacteremia episodes among 133 patients during 2005-2021. Of those patients, 7.7% required vasopressor support, and 7.0% died while in the hospital. The prevalence of isolates resistant to erythromycin, minocycline, and clindamycin increased from 8.6% during 2005-2017 to 21.6% during 2018-2021. Our genomic analysis demonstrated that sequence type 525 and clonal complex 25 were predominant in SDSE isolates collected during 2018-2021. In addition, those isolates had acquired 2 antimicrobial-resistance genes, ermB and tetM, via Tn916-like integrative and conjugative elements (ICEs). Phylogenetic analysis revealed clonal distribution of Tn916-like ICEs in SDSE isolates. Our findings suggest that Tn916-like ICEs contributed to the emergence and recent increase of multidrug-resistant SDSE bacteremia in this region of Japan

Spectroscopic evolution of dusty starburst galaxies

By using a one-zone chemical and spectrophotometric evolution model of a disk galaxy undergoing a dusty starburst, we investigate, numerically, the optical spectroscopic properties in order to explore galaxy evolution in distant clusters. We adopt an assumption that the degree of dust extinction (represented by $A_V$) depends on the ages of starburst populations in such a way that younger stars have larger $A_V$ (originally referred to as selective dust extinction by Poggianti & Wu 2000). In particular, we investigate how the time evolution of the equivalent widths of [OII]$\lambda$3727 and H$\delta$ is controlled by the adopted age dependence. This leads to three main results: (1) If a young stellar population (with the age of $\sim$ $10^6$ yr) is more heavily obscured by dust than an old one ($>$ $10^8$ yr), the galaxy can show an ``e(a)'' spectrum characterized by strong H$\delta$ absorption and relatively modest [OII] emission. (2) A dusty starburst galaxy with an e(a) spectrum can evolve into a poststarburst galaxy with an a+k (or k+a) spectrum 0.2 Gyr after the starburst and then into a passive one with a k-type spectrum 1 Gyr after the starburst. This result clearly demonstrates an evolutionary link between galaxies with different spectral classes (i.e., e(b), e(a), a+k, k+a, and k). (3) A dusty starburst galaxy can show an a+k or k+a spectrum even in the dusty starburst phase if the age-dependence of dust extinction is rather weak, i.e., if young starburst populations with different ages ($\le$ $10^7$ yr) are uniformly obscured by dust.Comment: 27 pages 12 figures,2001,ApJ,in pres