Phylogenetic and physiological diversity of sulphate-reducing bacteria isolated from a salt marsh sediment

Xenopus blastula cells activate different mesodermal genes as a concentration-dependent response to activin, which behaves like a morphogen. To understand how cells recognize morphogen concentration, we have bound naturally labeled activin to cells and related this to choice of gene activation. We find that the increasing occupancy of a single receptor type can cause cells to switch gene expression. Cells sense ligand concentration by the absolute number of occupied receptors per cell (100 and 300 molecules of bound activin induce Xbra and Xgsc, respectively, i.e., 2% and 6% of the total receptors) and not by a ratio of occupied to unoccupied receptors. The long duration of occupancy explains a previously described ratchet effect. Our results suggest a new concept of morphogen gradient formation and interpretation that is particularly well suited to the needs of early development.     

Methodology for Efficient Substrate Noise Analysis in Large-Scale Mixed-Signal Circuits

A methodology is proposed to efficiently analyze substrate noise coupled to a sensitive block due to an aggressor digital block in large-scale mixed-signal circuits. The methodology is based on identifying voltage domains on the substrate by exploiting the small spatial voltage differences on the ground distribution network of the aggressor circuit. Specifically, similarly biased regions on the substrate short-circuited by the ground network are determined, and each of these regions is represented by a single equivalent input port to the substrate. The remaining ports within that domain are ignored to reduce the computational complexity of the extraction process. An algorithm with linear time complexity is proposed to merge those substrate contacts exhibiting a voltage difference smaller than a specified value, identifying a voltage domain. An equivalent contact is placed at the geometric mean of the merged contacts, ignoring all of the remaining ports such as the source/drain junctions of the devices. The ground network impedance is updated for each merged contact based on the proposed algorithm to maintain sufficient accuracy of the noise voltage. The substrate with reduced input ports is extracted using an existing extraction tool to analyze the noise at the sense node. As compared to the full extraction of an aggressor circuit, the methodology achieves a reduction of more than four orders of magnitude in the number of extracted substrate resistors with a peak-to-peak error of 24%.     

Toward a systematic design methodology for large multigigahertzrapid single flux quantum circuits

Rapid single flux quantum (RSFQ) digital circuits have reached the level of medium- to large-scale of integration. At this level, existing design methodologies, developed specifically for RSFQ circuits, have become computationally inefficient. Applying mature semiconductor methodologies to the design of RSFQ circuits, one encounters substantial difficulties originating from the differences between both technologies. In this paper, a new design methodology aimed at large-scale RSFQ circuits is proposed. This methodology is based on a semiconductor semicustom design approach. An established design methodology for small-stale RSFQ digital circuits, based on circuit (junction-level) simulation and device parameter optimization, is used for the design of basic RSFQ cells. A library composed of about 20 basic RSFQ cells has been developed based on this approach. A novel design methodology for large-scale circuits, presented in this paper, is based on logic (gate-level) simulation and timing optimization. This methodology has been implemented around the Cadence integrated design environment and used successfully at the University of Rochester for the design of two large-scale digital circuits     

Exploiting the on-chip inductance in high-speed clock distributionnetworks

On-chip inductance effects can be used to improve the performance of high-speed integrated circuits. Specifically, inductance improves the signal slew rate (the rise time), virtually eliminates short-circuit power consumption and reduces the area of the active devices and repeaters inserted to optimize the performance of long interconnects. These positive effects suggest the development of design strategies that benefit from on-chip inductance. An example of a clock distribution network is presented to illustrate the process in which inductance can be used to improve the performance of high-speed integrated circuits     

Placement of Substrate Contacts to Minimize Substrate Noise in Mixed-Signal Integrated Circuits

The placement of substrate contacts in epi and non-epi technologies is analyzed in order to control and reduce the substrate noise amplitude and spreading. The choice of small or large substrate contacts or rings for each of the two major technologies is highlighted. Design guidelines for placing substrate contacts so as to improve the noise immunity of digital circuits in mixed-signal smart-power systems are also presented.     

Reactions of internal and external test-anxious students to counseling and behavior therapies.

Studied the responses of 36 test-anxious students, who differed on Rotter's Internal-External Control Scale, to 3 forms of therapy (counseling, systematic desensitization, and automated desensitization). Support was obtained for the prediction that internal Ss would show greater resistance to the control implied in the 2 behavior therapies than external Ss. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Abortifacient effect of intramuscular prostaglandin F2alpha analogue in early midtrimester pregnancy

Official physical examinations of migrant workers upon immigration are required before work permits are issued. The screening of 74,983 applicants during 1972 to 1974 revealed sera reactive to serological tests for syphilis in 0-8 per cent. (range 0-5 to 1-1 per cent.) of all persons concerned and fifteen cases of early syphilis. The incidence of recent infections among immigrants is lower than that reported among the inhabitants of Vienna. General statistics on the spread of venereal diseases among immigrant workers are not available after they start work. Some evidence is provided by those who had to be traced for compulsory examination because they had defaulted from treatment or follow-up, because they were suspected of clandestine prostitution, or because they were reported to be sources of infection. 257 (60-6 per cent.) of 414 individuals who were wanted for reasons of syphilis control could be located and eighteen (7 per cent.) of those who were examined had early infectious lesions.     

The feasibility of smoking bans on psychiatric units

Cryptococcal meningitis has a high mortality rate of central nervous infection. The patients usually die of the disease itself, or complications from increased intracranial pressure. Early diagnosis and treatment, including surgical drainage, will improve the results. In this series, twenty-one patients with high intracranial pressure (ICP > 300 mmH2 O) are presented. Fourteen received implantation of Ommaya reservoir to aspirate cerebrospinal fluid (CSF) for relief of symptoms of ICP. Meanwhile 4 of these 14 patients also received intraventricular injection of amphotericin B because of poor response to systemic drugs. Another seven patient received systemic drug therapy only. Survival during therapy occurred in 11 of 14 patients in the surgical group, compared with only 1 of 7 patients treated by drug therapy alone (P = 0.019). In the 14 patients who received implantation of an Ommaya reservoir, there was one complication of CSF leakage when the reservoir ruptured because of repeated aspiration. For patients with cryptococcal meningitis with high ICP, early implantation of an Ommaya reservoir will improve the survival rate.