Solitonic dispersive hydrodynamics: theory and observation

Ubiquitous nonlinear waves in dispersive media include localized solitons and extended hydrodynamic states such as dispersive shock waves. Despite their physical prominence and the development of thorough theoretical and experimental investigations of each separately, experiments and a unified theory of solitons and dispersive hydrodynamics are lacking. Here, a general soliton-mean field theory is introduced and used to describe the propagation of solitons in macroscopic hydrodynamic flows. Two universal adiabatic invariants of motion are identified that predict trapping or transmission of solitons by hydrodynamic states. The result of solitons incident upon smooth expansion waves or compressive, rapidly oscillating dispersive shock waves is the same, an effect termed hydrodynamic reciprocity. Experiments on viscous fluid conduits quantitatively confirm the soliton-mean field theory with broader implications for nonlinear optics, superfluids, geophysical fluids, and other dispersive hydrodynamic media.Comment: 8 pages, 5 figure

New Territories in Adult Education: Game-based Learning for Adult Learners

The purpose of this paper is to address the different approaches to game-based learning by focusing on applied examples and implications for adult education

Issues and Design Drivers for Deep Space Habitats

A cross-disciplinary team of scientists and engineers applied expertise gained in Lunar Lander development to the conceptual design of a long-duration, deep space habitat for Near Earth Asteroid (NEA) missions. The design reference mission involved two launches to assemble a 5-module vehicle for a 380-day round trip mission carrying 4 crew members. The conceptual design process yielded a number of interesting debates, some of which could be significant design drivers in a detailed Deep Space Habitat (DSH) design. These issues include: a) Launch loads: Potentially drives layout of equipment mounted to module floors or walls, and whether temporary internal structure is required to distribute launch loads to minimize shell mass; b) Unmanned loiter time: When added to an already lengthy mission, loiter time further drives risk and reliability, and poses issues for equipment shelf life such as material degradation or cryogenic fluids boil-off; c) Pointing and Visibility: A habitat embedded in a 5-module stack may drive Communications, Tracking, Guidance, and Navigation equipment out onto long booms to maintain line-of-sight visibility with targets. However, long booms will be more susceptible to disruption from exercise-induced vibration, potential damage during docking/undocking operations, and increased power distribution mass; d) Water: although it is assumed that a water processor will collect and recycle water, several interesting question were posed, such as: How much water to start with? Should potable water serve double-duty as radiation protection? And if so, should it be stowed in a single large tank, or smaller, portable containers? e) Design for repairability: one of the worst-case scenarios identified was a cabin depressurization that required suited repair from inside the module, potentially driving the need for long umbilical hoses or special equipment to allow smaller, mated modules to be used as safe havens for up to 180 days

Hepatocytes Traffic and Export Hepatitis B Virus Basolaterally by Polarity-Dependent Mechanisms

Viruses commonly utilize the cellular trafficking machinery of polarized cells to effect viral export. Hepatocytes are polarized in vivo, but most in vitro hepatocyte models are either nonpolarized or have morphology unsuitable for the study of viral export. Here, we investigate the mechanisms of trafficking and export for the hepadnaviruses hepatitis B virus (HBV) and duck hepatitis B virus (DHBV) in polarized hepatocyte-derived cell lines and primary duck hepatocytes. DHBV export, but not replication, was dependent on the development of hepatocyte polarity, with export significantly abrogated over time as primary hepatocytes lost polarity. Using Transwell cultures of polarized N6 cells and adenovirus-based transduction, we observed that export of both HBV and DHBV was vectorially regulated and predominantly basolateral. Monitoring of polarized N6 cells and nonpolarized C11 cells during persistent, long-term DHBV infection demonstrated that newly synthesized sphingolipid and virus displayed significant colocalization and fluorescence resonance energy transfer, implying cotransportation from the Golgi complex to the plasma membrane. Notably, 15% of virus was released apically from polarized cells, corresponding to secretion into the bile duct in vivo, also in association with sphingolipids. We conclude that DHBV and, probably, HBV are reliant upon hepatocyte polarity to be efficiently exported and this export is in association with sphingolipid structures, possibly lipid rafts. This study provides novel insights regarding the mechanisms of hepadnavirus trafficking in hepatocytes, with potential relevance to pathogenesis and immune tolerance. © 2011, American Society for Microbiology

One Family at a Time: A Prevention Program for At-Risk Parents

The purpose of this study was to examine the effectiveness of a psychoeducational parenting program with at-risk parents of young children. At-risk was defined as excessive parental use of verbal and corporal punishment combined with low-income status. All families were seen for 10 weeks, either individually or in very small groups. Results showed that compared with the control group, parents participating in the program significantly decreased their levels of verbal and corporal punishment, anger, stress, and reported child behavior problems; results were maintained at follow-up. Implications for counselors are provided

A comparison study of the degradative effects and safety implications of UVC and 405 nm germicidal light sources for endoscope storage

Storage of flexible endoscopes under germicidal ultraviolet (UVC) light has been associated with degradation of device material leading to failure and increased risk to patients. 405 nm germicidal light presents a possible alternative, potentially providing effective bacterial inactivation without material damage. Samples of endoscope material were exposed to UVC and 405 nm germicidal light sources and a broad spectrum light source control. Material properties were monitored using FTIR, AFM, contact angle and confocal microscopy. Significant changes were observed with samples exposed to the UVC source, with variations in FTIR spectra indicative of side chain scission, a decrease in contact angle from 82.6° to 61.4°, an increase in average surface roughness from 2.34 nm to 68.7 nm and visible cracking of the surface. In contrast samples exposed to the 405 nm light source showed little to no changes, with any variations being comparable to those seen on samples exposed to the broad spectrum control. Bacterial adhesion tests on samples showed an 86.8% increase in Pseudomonas aeruginosa adhesion on UVC exposed samples and no significant increase in adhesion with samples exposed to the other light sources. 405 nm germicidal light therefore potentially represents a safer alternative to UVC light for use in flexible endoscope storage