Imaging of the optic disc and retinal nerve fiber layer: the effects of age, optic disc area, refractive error, and gender.

We cross-sectionally examined the relationship between age, optic disc area, refraction, and gender and optic disc topography and retinal nerve fiber layer (RNFL) measurements, using optical imaging techniques. One eye from each of 155 Caucasian subjects (age range 23.0-80.8 y) without ocular pathology was included. Measurements were obtained by using the Heidelberg Retina Tomography (HRT), the GDx Nerve Fiber Analyzer, and the Optical Coherence Tomograph (OCT). The effects of age were small (R2 < 17%) and were limited to specific HRT, GDx, and OCT parameters. Disc area was significantly associated with most HRT parameters and isolated GDx and OCT parameters. Refraction and gender were not significantly associated with any optic disc or RNFL parameters. Although effects of age on the optic disc and RNFL are small, they should be considered in monitoring ocular disease. Optic disc area should be considered when cross-sectionally evaluating disc topography and, to a lesser extent, RNFL thickness.     

Fair attribution of functional contribution in artificial and biological networks

This letter presents the multi-perturbation Shapley value analysis (MSA), an axiomatic, scalable, and rigorous method for deducing causal function localization from multiple perturbations data. The MSA, based on fundamental concepts from game theory, accurately quantifies the contributions of network elements and their interactions, overcoming several shortcomings of previous function localization approaches. Its successful operation is demonstrated in both the analysis of a neurophysiological model and of reversible deactivation data. The MSA has a wide range of potential applications, including the analysis of reversible deactivation experiments, neuronal laser ablations, and transcranial magnetic stimulation "virtual lesions," as well as in providing insight into the inner workings of computational models of neurophysiological systems.     

Localization of function via lesion analysis

This article presents a general approach for employing lesion analysis to address the fundamental challenge of localizing functions in a neural system. We describe functional contribution analysis (FCA), which assigns contribution values to the elements of the network such that the ability to predict the network's performance in response to multilesions is maximized. The approach is thoroughly examined on neurocontroller networks of evolved autonomous agents. The FCA portrays a stable set of neuronal contributions and accurate multilesion predictions that are significantly better than those obtained based on the classical single lesion approach. It is also used for a detailed synaptic analysis of the neurocontroller connectivity network, delineating its main functional backbone. The FCA provides a quantitative way of measuring how the network functions are localized and distributed among its elements. Our results question the adequacy of the classical single lesion analysis traditionally used in neuroscience and show that using lesioning experiments to decipher even simple neuronal systems requires a more rigorous multilesion analysis.     

Controlled analysis of neurocontrollers with informational lesioning

How does one aim to understand neural information processing? One of the difficult first challenges is to identify the roles of the network's elements. To this end a functional contribution analysis (FCA) method has been developed and applied for studying the neurocontrollers of evolutionary autonomous agents (EAAs). The FCA processes data composed of multiple lesion experiments and the corresponding performance levels that the agent obtains under these lesions. It calculates the contribution values (CVs) of the network's elements such that the ability to predict the agent's performance under new, unseen lesions is maximized. Previous analysis has found a strong dependence of the CVs and the prediction error on the specific type of lesioning method used, i.e. on the way in which the activity of lesioned neurons is disrupted. We present a new, informational lesioning method (ILM), which views a lesion as a noisy channel and applies a controlled lesion to the network by varying the lesioning level from large to arbitrarily small magnitudes. Studying the ILM within the FCA framework, our main results are threefold: first, that lower lesioning levels permit more accurate FCA predictions; second, that the usage of minute ILM lesioning levels can uncover the long-term effects of elements on the network's functioning; and third, that as the lesioning level decreases, the CVs tend to approach limit values, reflecting the importance of these elements in the intact, normal-functioning neurocontroller.     

Lack of Long-Lasting Consequences of Starvation on Eating Pathology in Jewish Holocaust Survivors of Nazi Concentration Camps.

The purpose of the present study was to investigate whether Holocaust survivors will show the same eating pathologies that were found in other participants who had also undergone starvation. Fifty-five Holocaust survivors and 43 matched control participants answered a questionnaire designed to explore eating problems and pathologies described in the literature as lasting for decades after a period of severe food restriction. Confirmation of the survivors' reports was obtained from their children. No significant differences in current eating habits were found between the Holocaust survivors and their matched controls. Prolonged starvation in Holocaust survivors did not lead to disordered eating habits in the sample. These results conflict with the notion that severe starvation consistently leads to food preoccupation and disordered eating. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Global Communication and Foreign Policy

This study investigated the effects global communication is having on the formulation and conduct of foreign policy and showed that it both constrains leaders and officials yet provides them with opportunities to advance their goals. The article presents a taxonomy where global communication is viewed as an actor in the policy process with corresponding attributes of type, activity, context, and concept. Four types of actors are identified: controlling, constraining, intervening, and instrumental. The article critically and respectively examines concepts developed to explain each type: the "CNN Effect theory,""real-time policy,""international political brokerage," and "media diplomacy." Although some of these concepts were found to be useful, major progress in this field requires interdisciplinary research based on joint application of theories and models from both communication and international relations.     

Prefrontal and parietal regions are involved in naming of objects seen from unusual viewpoints.

Object naming is commonly used for demonstrating semantic memory abilities, known to be affected in normal aging. Yet, neuropsychological assessments of older people do not reflect irregularities. The authors used a test with 2 levels of naming complexity by 2 kinds of stimuli: common objects pictured from a conventional viewpoint (usual condition) or from an unconventional viewpoint (unusual condition). The authors studied naming performance with 129 healthy participants, aged 20-85 years. For the usual stimuli, the success rate was high (90.9%), with no reduction in performance until 65 years of age. However, for the unusual stimuli, there was a marked reduction in performance with age. Brain activity was studied on 11 healthy young participants (20-30 years of age) using functional magnetic resonance imaging. The usual condition activated brain regions associated with visual perception, language, and memory. Additional brain regions associated with semantic searching and decision making were obtained in the unusual condition in the prefrontal cortex (Brodmann's area [BA] 9 and BA 47) and anterior cingulate (BA 32). The results suggest that the poor naming performance for unusual-viewed objects in older people might be related to the shrinkage of frontal gray matter with age. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Minimum energy transmission scheduling subject to deadline constraints

We consider the problem of transmission scheduling of data over a wireless fading channel with hard deadline constraints. Our system consists of N users, each with a fixed amount of data that must be served by a common deadline. Given that, for each user, the channel fade state determines the throughput per unit of energy expended, our objective is to minimize the overall expected energy consumption while satisfying the deadline constraint. We consider both a linear and a strictly convex rate-power curve and obtain optimal solutions, based on dynamic programming (DP), and tractable approximate heuristics in both cases. For the special non-fading channel case with convex rate-power curve, an optimal solution is obtained based on the Shortest Path formulation. In the case of a linear rate-power curve, our DP solution has a nice “threshold” form; while for the convex rate-power curve we are able to obtain a heuristic algorithm with comparable performance with that of the optimal scheduling scheme. Alessandro Tarello received his M.Sc. and Ph.D. degrees in Electrical and Communication Engineering from Politecnico di Torino, Torino, Italy, in 2002 and 2006 respectively. He currently holds a Postdoctoral position at Politecnico di Torino. He visited the Laboratory for Information and Decision Systems at MIT, Cambridge, MA, USA, in 2004 and 2005. During Summer 2005 he also visited the Jet Propulsion Laboratory, Pasadena, CA, USA. He received the best student paper award at the Third International Symposium on Modeling and Optimization in Mobile, Ad-Hoc and Wireless Networks (WiOPT’05). His research interests are in the fields of stochastic and fluid models for performance evaluation of packet networks and optimization techniques for wireless and ad-hoc networks. Jun Sun received his B.S. degree in Computer Engineering from University of Florida in 1997 and his M.S. in Electrical Engineering from Massachusetts Institute of Technology in 2002. He is currently a Ph.D. student in the Laboratory for Information and Decision Systems at MIT. His research interest is on communication networks with emphasis on satellite and wireless networks. Murtaza Zafer received his B.Tech degree in Electrical Engineering from the Indian Institute of Technology (IIT), Madras, India, in 2001 and his M.S. degree in Electrical Engineering and Computer Science from the Massachusetts Institute of Technology (MIT), MA, USA, in 2003. Currently, he is pursuing his doctoral studies at the Laboratory for Information and Decision Systems (LIDS) in the department of Electrical Engineering and Computer Science at MIT. He spent the summer of 2004 at the Mathematical Sciences Research center, Bell Laboratories and the summer of 2003 at Qualcomm, Inc. His research interests lie in queueing theory, information theory, control and optimization theory and its applications to wireless communication networks. He is the co-recipient of the best Student Paper award at WiOpt, 2005. He also received the Siemens (India) and Philips (India) award for academic excellence. Eytan Modiano received his B.S. degree in Electrical Engineering and Computer Science from the University of Connecticut at Storrs in 1986 and his M.S. and PhD degrees, both in Electrical Engineering, from the University of Maryland, College Park, MD, in 1989 and 1992 respectively. He was a Naval Research Laboratory Fellow between 1987 and 1992 and a National Research Council Post Doctoral Fellow during 1992–1993. Between 1993 and 1999 he was with MIT Lincoln Laboratory where he was the project leader for MIT Lincoln Laboratory’s Next Generation Internet (NGI) project. Since 1999 he has been on the faculty at MIT; where he is presently an Associate Professor. His research is on communication networks and protocols with emphasis on satellite, wireless, and optical networks. He is currently an Associate Editor for Communication Networks for IEEE Transactions on Information Theory and for The International Journal of Satellite Communications. He had served as a guest editor for IEEE JSAC special issue on WDM network architectures; the Computer Networks Journal special issue on Broadband Internet Access; the Journal of Communications and Networks special issue on Wireless Ad-Hoc Networks; and for IEEE Journal of Lightwave Technology special issue on Optical Networks. He is the Technical Program co-chair for Wiopt 2006, IEEE Infocom 2007, and ACM MobiHoc 2007.     

Regiocontrolled Synthesis of 4-Halo-5,6-Dihydro-4H-1,2-Oxazines; A Novel Route for α-Fluorovinyl Ketones

Regiocontrolled deprotonation (e.g. lithiation) of 3-methyl-4-H-5,6-dihydro-1,2-oxazine 1 is achieved at −65°C. The lithiated compound reacts cleanly with the halogens Cl₂, Br₂ and I₂ at low temperatures (−65°C) to give the corresponding 4-halo derivatives. Reaction of the 4-iodo compound 2a with KF in diethyleneglycol gives the elimination product 4 whereas the bromo compound 2b reacts under substitution to the 4-fluoro derivatives 5. The fluorooxazine derivatives 8a-c were converted to the αfluoroenones 11 a-c via the oxoiminium salts 10a-c. The U.V. and ¹HNMR of the novel series of halides 2a-c and 5 were studied.     

Flip-flop of doxorubicin across erythrocyte and lipid membranes

Doxorubicin, an anticancer drug, is extruded from multidrug resistant (MDR) cells and from the brain by P-glycoprotein located in the plasma membrane and the blood-brain barrier, respectively. MDR-type drugs are hydrophobic and, as such, enter cells by diffusion through the membrane without the requirement for a specific transporter. The apparent contradiction between the presumably free influx of MDR-type drugs into MDR cells and the efficient removal of the drugs by P-glycoprotein, an enzyme with a limited ATPase activity, prompted us to examine the mechanism of passive transport within the membrane. The kinetics of doxorubicin transport demonstrated the presence of two similar sized drug pools located in the two leaflets of the membrane. The transbilayer movement of doxorubicin occurred by a flip-flop mechanism of the drug between the two membrane leaflets. At 37 degrees, the flip-flop exhibited a half-life of 0.7 min, in both erythrocyte membranes and cholesterol-containing lipid membranes. The flip-flop was inhibited by cholesterol and accelerated by high temperatures and the fluidizer benzyl alcohol. The rate of doxorubicin flux across membranes is determined by both the massive binding to the membranes and the slow flip-flop across the membrane. The long residence-time of the drug in the inner leaflet of the plasma membrane allows P-glycoprotein a better opportunity to remove it from the cell.