Effects of exercising before versus after eating on dieting and exercise evaluations: A preliminary investigation.

Psychological processes may play a role in the evaluation of the effectiveness of exercise and subsequent food intake. In order to further investigate this phenomenon, the effects of the timing of exercise relative to an eating opportunity were evaluated. Female undergraduate participants who were of average weight and did not exercise regularly were randomly assigned to one of three conditions (exercise before eating [n = 10], exercise after eating [n = 11], or no exercise [n = 12]). Expectations of the effectiveness of the exercise, value of dieting, and intake were assessed. Participants who exercised after eating had higher expectations of the effectiveness of the exercise than those who exercised before eating, while those who exercised before eating reported valuing dieting more than controls. No effects on intake emerged; therefore, there appears to be a disconnect between dieting appraisals and actual eating behaviour. The results are discussed in relation to theories on conflicting goals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sub-Compartmental Organization of Golgi-Resident N-Glycan Processing Enzymes in Plants

In all eukaryotes, the Golgi apparatus is the main site of protein glycosylation. It is widely     

Steric Crowding Makes Challenging C(sp3)-F Reductive Eliminations Feasible

A high-yielding fluorination of (triphos)Pt-R(+) has been achieved using an array of F(+) sources, with XeF(2) yielding R-F in minutes. The C-F coupling proved to be a stereoretentive process that proceeds via a concerted reductive elimination from a putative dicationic Pt(IV) center. The larger the steric congestion of the (triphos)Pt-C(sp3) (+) complexes, the more efficient the fluorination, seemingly a result of sterically accelerated C-F reductive elimination along with simultaneous deceleration of its competing processes (β-H elimination).     

Room-Temperature Mechanical Properties and Slow Crack Growth Behavior of Mg2Si Thermoelectric Materials

Mg₂Si is of interest as a thermoelectric (TE) material in part due to its low materials cost, lack of toxic components, and low mass density. However, harvesting of waste heat subjects TE materials to a range of mechanical and thermal stresses. To understand and model the material??s response to such stresses, the mechanical properties of the TE material must be known. The Mg₂Si specimens included in this study were powder processed and then sintered via pulsed electrical current sintering. The elastic moduli (Young??s modulus, shear modulus, and Poisson??s ratio) were measured using resonant ultrasound spectroscopy, while the hardness and fracture toughness were examined using Vickers indentation. Also, the Vickers indentation crack lengths were measured as a function of time in room air to determine the susceptibility of Mg₂Si to slow crack growth.     

Polymeric Nanoparticles as a Self-Adjuvanting Peptide Vaccine Delivery System: The Role of Shape

Antigens incorporated in subunit vaccines are typically poorly immunogenic, so a strong immunostimulant (adjuvant) and/or delivery system is required to boost immunogenicity. In this work, the various functional polymer nanostructures, that is, rods, worms, spheres, and tadpoles are used to develop potent peptide antigen delivery systems. The antigen PADRE-J8 (PJ8), derived from Group A Streptococcus (GAS) M-protein, is either physically mixed or chemically conjugated to polymeric nanoparticles of different shapes. The physical mixture of polymeric nanoparticles and antigen is more effective in inducing antibody production than their chemical conjugates. Moreover, rod-shaped polymeric nanoparticles in physical mixture with PJ8 elicited higher and more opsonic antibody titers than powerful complete Freund's adjuvant (CFA)-adjuvanted antigen. Herein, for the first time it is demonstrated that a) the block copolymer, in nanoparticle form, can act as an immune adjuvant, b) nanoparticle shape plays a crucial role in their immunogenicity, and c) antigen conjugation is not required, nor is antigen encapsulation or absorption.     

Accelerated Ionic Motion in Amorphous Memristor Oxides for Nonvolatile Memories and Neuromorphic Computing

Memristive devices based on mixed ionic–electronic resistive switches have an enormous potential to replace today's transistor‐based memories and Von Neumann computing architectures thanks to their ability for nonvolatile information storage and neuromorphic computing. It still remains unclear however how ionic carriers are propagated in amorphous oxide films at high local electric fields. By using memristive model devices based on LaFeO₃ with either amorphous or epitaxial nanostructures, we engineer the structural local bonding units and increase the oxygen‐ionic diffusion coefficient by one order of magnitude for the amorphous oxide, affecting the resistive switching operation. We show that only devices based on amorphous LaFeO₃ films reveal memristive behavior due to their increased oxygen vacancy concentration. We achieved stable resistive switching with switching times down to microseconds and confirm that it is predominantly the oxygen‐ionic diffusion character and not electronic defect state changes that modulate the resistive switching device response. Ultimately, these results show that the local arrangement of structural bonding units in amorphous perovskite films at room temperature can be used to largely tune the oxygen vacancy (defect) kinetics for resistive switches (memristors) that are both theoretically challenging to predict and promising for future memory and neuromorphic computing applications.     

Mobile ad hoc networking: imperatives and challenges

Mobile ad hoc networks (MANETs) represent complex distributed systems that comprise wireless mobile nodes that can freely and dynamically self-organize into arbitrary and temporary, “ad-hoc” network topologies, allowing people and devices to seamlessly internetwork in areas with no pre-existing communication infrastructure, e.g., disaster recovery environments. Ad hoc networking concept is not a new one, having been around in various forms for over 20 years. Traditionally, tactical networks have been the only communication networking application that followed the ad hoc paradigm. Recently, the introduction of new technologies such as the Bluetooth, IEEE 802.11 and Hyperlan are helping enable eventual commercial MANET deployments outside the military domain. These recent evolutions have been generating a renewed and growing interest in the research and development of MANET. This paper attempts to provide a comprehensive overview of this dynamic field. It first explains the important role that mobile ad hoc networks play in the evolution of future wireless technologies. Then, it reviews the latest research activities in these areas, including a summary of MANET’s characteristics, capabilities, applications, and design constraints. The paper concludes by presenting a set of challenges and problems requiring further research in the future.     

Syndrome: a light‐weight approach to improving TCP performance in mobile wireless networks

It is well known that the performance of TCP deteriorates in a mobile wireless environment. This is due to the fact that although the majority of packet losses are results of transmission errors over the wireless links, TCP senders still take packet loss as an indication of congestion, and adjust their congestion windows according to the additive increase and multiplicative decrease (AIMD) algorithm. As a result, the throughput attained by TCP connections in the wireless environment is much less than it should be. The key problem that leads to the performance degradation is that TCP senders are unable to distinguish whether packet loss is a result of congestion in the wireline network or transmission errors on the wireless links. In this paper, we propose a light‐weight approach, called syndrome, to improving TCP performance in mobile wireless environments. In syndrome, the BS simply counts, for each TCP connection, the number of packets that it relays to the destination host so far, and attaches this number in the TCP header. Based on the combination of the TCP sequence number and the BS‐attached number and a solid theoretical base, the destination host will be able to tell where (on the wireline or wireless networks) packet loss (if any) occurs, and notify TCP senders (via explicit loss notification, ELN) to take appropriate actions. If packet loss is a result of transmission errors on the wireless link, the sender does not have to reduce its congestion window. Syndrome is grounded on a rigorous, analytic foundation, does not require the base station to buffer packets or keep an enormous amount of states, and can be easily incorporated into the current protocol stack as a software patch. Through simulation studies in ns‐2 (UCB, LBNL, VINT network simulator, http://www‐mash.cs.berkeley.edu/ns/ ), we also show that syndrome significantly improves the TCP performance in wireless environments and the performance gain is comparable to the heavy‐weight SNOOP approach (either with local retransmission or with ELN) that requires the base station to buffer, in the worst case, a window worth of packets or states. Copyright © 2001 John Wiley & Sons, Ltd.