General library standards

Paul Evan Peters begins his discussion of library standards with a convincing argument that the acceptance by librarians of the need for order and standards is not a character flaw. Rather, in promoting the use of standards, librarians are efficiently forwarding their missions to build and organize collections and to make them accessible to their clients. Pointing out the economic realities of contemporary libraries, Peters further argues that standards are appealing because they help librarians to control costs. Paul Evan Peters, systems coordinator for the New York Public Library, is vice chairperson of the National Information Standards Organization and principal representative of the American Library Association to Accredited Standards Committee X3 (Information Processing Systems). Address for correspondence.     

Analysis of a laminar-flow diffusional mixer for directed self-assembly of liposomes

The present work describes the operation and simulation of a microfluidic laminar-flow mixer. Diffusive mixing takes place between a core solution containing lipids in ethanol and a sheath solution containing aqueous buffer, leading to self assembly of liposomes. Present device architecture hydrodynamically focuses the lipid solution into a cylindrical core positioned at the center of a microfluidic channel of 125 × 125-μm² cross-section. Use of the device produces liposomes in the size range of 100–300 nm, with larger liposomes forming at greater ionic strength in the sheath solution and at lower lipid concentration in the core solution. Finite element simulations compute the concentration distributions of solutes at axial distances of greater than 100 channel widths. These simulations reduce computation time and enable computation at long axial distances by utilizing long hexahedral elements in the axial flow region and fine tetrahedral elements in the hydrodynamic focusing region. Present meshing technique is generally useful for simulation of long microfluidic channels and is fully implementable using comsol Multiphysics. Confocal microscopy provides experimental validation of the simulations using fluorescent solutions containing fluorescein or enhanced green fluorescent protein.     

Discrepancies in accelerometer-measured physical activity in children due to cut-point non-equivalence and placement site

Abstract This study examined dissonance in physical activity (PA) between two youth-specific hip-derived intensity cut-points for the Actiwatch (AW), and compared PA between hip and wrist placements using site-specific cut-points. Twenty-four children aged 11.2?±?0.5 years wore the AW on the right hip and non-dominant wrist during a typical school day. Minutes of sedentary behaviour and vigorous activity were greater using Puyau et al. (2002) cut-points, but light, moderate, and moderate-to-vigorous (MVPA) were greater when derived using Puyau et al. (2004) cut-points (P?相似文献