Chemical pump study

Sorption pumps applicable to the Pioneer Venus Mass Spectrometer Experiment were investigated. The pump requirements are discussed, and a survey of the existing pumps presented. Zirconium and zirconium graphite products were found to be the most promising among the getter materials surveyed. A preliminary pump design for the noble gas experiment is discussed

Dissolved iron in the tropical and subtropical Atlantic Ocean

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95150/1/gbc1254.pd

SEPARATION OF MITOCHONDRIAL MEMBRANES OF NEUROSPORA CRASSA : II. Submitochondrial Localization of the Isoleucine-Valine Biosynthetic Pathway

Separation of Neurospora mitochondrial outer membranes from the inner membrane/matrix fraction was effected by digitonin treatment and discontinuous density gradient centrifugation. The solubilization of four isoleucine-valine biosynthetic enzymes was studied as a function of digitonin concentration and time of incubation in the detergent. The kinetics of the appearance of valine biosynthetic function in fractions outside of the inner membrane/matrix fraction, coupled with enzyme solubilization patterns similar to that for the matrix marker, mitochondrial malate dehydrogenase, indicate that the four isoleucine-valine pathway enzymes are localized in the mitochondrial matrix

"It could have been bigger, but its residents like it as is": A Study of Small Town Libraries in Moore County, North Carolina

Large, urban institutions are well represented in American public library history, but the stories of libraries in small towns or in rural areas are not as well represented. During the twentieth century, local citizens in six small Moore County, North Carolina towns ("small" here defined as towns having less than five thousand residents) established and maintained local public libraries. Some of the libraries failed over time, some succeeded, but all of them went through a process of finding their place in their community and governmental environments, environments that were themselves changing with the times. Using newspaper articles, augmented with interviews and direct observation, this is a study of those libraries and the people who created them - in the context of their times and circumstances, and in the context of how they were and are viewed by the profession of librarianship

Everybody's talking at me: information flow in a command and control environment

Increasing requirements to enhance mobility, coupled with a need to defend troops from the lethality of the modern battlefield, are causing the Army to consider new organizational arrangements and new communication and information technologies for the command and control (C2) of battalion-level combat units. It is important to understand the role information plays in enhancing the ability of C2 team members to make critical decisions. This study describes an information flow analysis, using four concurrent and correlated coding schemas, of videotapes taken of an active Army combat unit engaging in a combat simulation exercise. Coding of 135 out of 1035 minutes of simulated combat in an artillery Tactical Operations Center seems to indicate that information flow in such a task environment is constant, diverse, both directional and omnidirectional, both focused and generalized, and germane to multiple levels of situational awareness at the same time

Direct excitation of the forbidden clock transition in neutral 174Yb atoms confined to an optical lattice

We report direct single-laser excitation of the strictly forbidden (6s^2)^1S_0 -(6s6p)^3P_0 clock transition in the even 174Yb isotope confined to a 1D optical lattice. A small (~1.2 mT) static magnetic field was used to induce a nonzero electric dipole transition probability between the clock states at 578.42 nm. Narrow resonance linewidths of 20 Hz (FHWM) with high contrast were observed, demonstrating a record neutral-atom resonance quality factor of 2.6x10^13. The previously unknown ac Stark shift-canceling (magic) wavelength was determined to be 759.35+/-0.02 nm. This method for using the metrologically superior even isotope can be easily implemented in current Yb and Sr lattice clocks, and can create new clock possibilities in other alkaline earth-like atoms such as Mg and Ca.Comment: Submitted to Physics Review Letter

Impact on follow-up strategies in patients with primary sclerosing cholangitis.

BACKGROUND & AIMS Evidence for the benefit of scheduled imaging for early detection of hepatobiliary malignancies in primary sclerosing cholangitis (PSC) is limited. We aimed to compare different follow-up strategies in PSC with the hypothesis that regular imaging improves survival. METHODS We collected retrospective data from 2975 PSC patients from 27 centres. Patients were followed from the start of scheduled imaging or in case of clinical follow-up from 1 January 2000, until death or last clinical follow-up alive. The primary endpoint was all-cause mortality. RESULTS A broad variety of different follow-up strategies were reported. All except one centre used regular imaging, ultrasound (US) and/or magnetic resonance imaging (MRI). Two centres used scheduled endoscopic retrograde cholangiopancreatography (ERCP) in addition to imaging for surveillance purposes. The overall HR (CI95%) for death, adjusted for sex, age and start year of follow-up, was 0.61 (0.47-0.80) for scheduled imaging with and without ERCP; 0.64 (0.48-0.86) for US/MRI and 0.53 (0.37-0.75) for follow-up strategies including scheduled ERCP. The lower risk of death remained for scheduled imaging with and without ERCP after adjustment for cholangiocarcinoma (CCA) or high-grade dysplasia as a time-dependent covariate, HR 0.57 (0.44-0.75). Hepatobiliary malignancy was diagnosed in 175 (5.9%) of the patients at 7.9 years of follow-up. Asymptomatic patients (25%) with CCA had better survival if scheduled imaging had been performed. CONCLUSIONS Follow-up strategies vary considerably across centres. Scheduled imaging was associated with improved survival. Multiple factors may contribute to this result including early tumour detection and increased endoscopic treatment of asymptomatic benign biliary strictures