Unification Grammars and Off-Line Parsability

Unification grammars are known to be Turing-equivalent; given a grammar G and a word w, it is undecidable whether w L(G). In order to ensure decidability, several constraints on grammars, commonly known as off-line parsability (OLP), were suggested, such that the recognition problem is decidable for grammars which satisfy OLP. An open question is whether it is decidable if a given grammar satisfies OLP. In this paper we investigate various definitions of OLP and discuss their interrelations, proving that some of the OLP variants are indeed undecidable. We then present a novel, decidable OLP constraint which is more liberal than the existing decidable ones.     

Silver carboxylate nanostructure nucleation and growth on AgBr crystals

The initial stage of the reaction between sodium stearate (NaSt) and AgNO(3) produces silver stearate (AgSt) micelles, [(C(18)H(35)O(2))(x)(Na(x-y))(Ag(y))(H(2)O)(z)], and aggregations of these AgSt micelles in the form of cubic pre-AgSt crystals. When cubic grains of 50?nm AgBr are added to the NaSt dispersion prior to the AgNO(3), the reaction proceeds to form the silver stearate micelles, but not the aggregation of those micelles. Instead, the {111} silver ion planes of the cubic AgBr crystal corners provide nucleation sites for silver stearate micelle deposition and crystal growth. After nucleation, the AgSt micelles evolve into nanostructured bud-like formations via an epitaxial interface on one or several corners of each AgBr cubic crystal. Over time, additional AgSt micelle deposition enables the buds to grow longer into strand-like structures, which then connect to form the beginnings of the ultimate silver stearate crystal plates.     

Algorithm design for a class of base station location problems in sensor networks

Base station placement has significant impact on sensor network performance. Despite its significance, results on this problem remain limited, particularly theoretical results that can provide performance guarantee. This paper proposes a set of procedure to design (1− ε) approximation algorithms for base station placement problems under any desired small error bound ε > 0. It offers a general framework to transform infinite search space to a finite-element search space with performance guarantee. We apply this procedure to solve two practical problems. In the first problem where the objective is to maximize network lifetime, an approximation algorithm designed through this procedure offers 1/ε² complexity reduction when compared to a state-of-the-art algorithm. This represents the best known result to this problem. In the second problem, we apply the design procedure to address base station placement problem when the optimization objective is to maximize network capacity. Our (1− ε) approximation algorithm is the first theoretical result on this problem. Yi Shi received his B.S. degree from University of Science and Technology of China, Hefei, China, in 1998, a M.S. degree from Institute of Software, Chinese Academy of Science, Beijing, China, in 2001, and a second M.S. degree from Virginia Tech, Blacksburg, VA, in 2003, all in computer science. He is currently working toward his Ph.D. degree in electrical and computer engineering at Virginia Tech. While in undergraduate, he was a recipient of Meritorious Award in International Mathematical Contest in Modeling and 1997 and 1998, respectively. His current research focuses on algorithms and optimizations for wireless sensor networks, wireless ad hoc networks, UWB-based networks, and SDR-based networks. His work has appeared in journals and highly selective international conferences (ACM Mobicom, ACM Mobihoc, and IEEE Infocom). Y. Thomas Hou received the B.E. degree from the City College of New York in 1991, the M.S. degree from Columbia University in 1993, and the Ph.D. degree from Polytechnic University, Brooklyn, New York, in 1998, all in Electrical Engineering. Since Fall 2002, he has been an Assistant Professor at Virginia Tech, the Bradley Department of Electrical and Computer Engineering, Blacksburg, VA. His current research interests are radio resource (spectrum) management and networking for software-defined radio wireless networks, optimization and algorithm design for wireless ad hoc and sensor networks, and video communications over dynamic ad hoc networks. From 1997 to 2002, Dr. Hou was a Researcher at Fujitsu Laboratories of America, Sunnyvale, CA, where he worked on scalable architectures, protocols, and implementations for differentiated services Internet, service overlay networking, video streaming, and network bandwidth allocation policies and distributed flow control algorithms. Prof. Hou is a recipient of an Office of Naval Research (ONR) Young Investigator Award (2003) and a National Science Foundation (NSF) CAREER Award (2004). He is a Co-Chair of Technical Program Committee of the Second International Conference on Cognitive Radio Oriented Wireless Networks and Communications (CROWNCOM 2007), Orlando, FL, August 1–3, 2007. He also was the Chair of the First IEEE Workshop on Networking Technologies for Software Defined Radio Networks, September 25, 2006, Reston, VA. Prof. Hou holds two U.S. patents and has three more pending. Alon Efrat earned his Bachelor in Applied Mathematics from the Technion (Israel’s Institute of Technology) in 1991, his Master in Computer Science from the Technion in 1993, and his Ph.D in Computer Science from Tel-Aviv University in 1998. During 1998–2000 he was a Post Doctorate Research Associate at the Computer Science Department of Stanford University, and at IBM Almaden Research Center. Since 2000, he is an assistant professor at the Computer Science Department of the University of Arizona. His main research areas are Computational Geometry, and its applications to sensor networks and medical imaging.     

Completeness in Two-Party Secure Computation: A Computational View

A Secure Function Evaluation (SFE) of a two-variable function f(·,·) is a protocol that allows two parties with inputs x and y to evaluate f(x,y) in a manner where neither party learns "more than is necessary". A rich body of work deals with the study of completeness for secure two-party computation. A function f is complete for SFE if a protocol for securely evaluating f allows the secure evaluation of all (efficiently computable) functions. The questions investigated are which functions are complete for SFE, which functions have SFE protocols unconditionally and whether there are functions that are neither complete nor have efficient SFE protocols. The previous study of these questions was mainly conducted from an information theoretic point of view and provided strong answers in the form of combinatorial properties. However, we show that there are major differences between the information theoretic and computational settings. In particular, we show functions that are considered as having SFE unconditionally by the combinatorial criteria but are actually complete in the computational setting. We initiate the fully computational study of these fundamental questions. Somewhat surprisingly, we manage to provide an almost full characterization of the complete functions in this model as well. More precisely, we present a computational criterion (called computational row non-transitivity) for a function f to be complete for the asymmetric case. Furthermore, we show a matching criterion called computational row transitivity for f to have a simple SFE (based on no additional assumptions). This criterion is close to the negation of the computational row non-transitivity and thus we essentially characterize all "nice" functions as either complete or having SFE unconditionally.     

光学检测系统的优化和评估的新方法

PCB厂商使用自动光学检测仪的目的是为了检测到重要的缺陷,而对于一些特殊设计和装饰性设计则不需要检测。如果要达到这一效果,就必须适当调整系统的检测参数。提供一种衡量AOI侦测性能的新颖方法。此种方法可以尽可能的减少漏测或误报产生的几率,通过考量漏测与误报的各自的成本,客户可据此结果来决定特定的机器的配备。关于自动检测设备选型机制示意图和方法,相关的实用工具及生产领域的简易实施方法也作了说明。     

Cost optimization of cross-laminated timber panels in one-way bending

European Journal of Wood and Wood Products - For the purposes of structural design, cross-laminated timber (CLT) panels are typically chosen from tables detailing standardized layups. While this is...     

In vivo performances of pure Zn and Zn–Fe alloy as biodegradable implants

The disadvantage of current biodegradable metals such as Mg and Fe is the release of hydrogen gas in vivo that can cause gas embolism and the production of voluminous iron oxide that can cause inflammation, respectively. Such considerations have turned focus towards Zn as an alternative. This is based on the fact that Zn plays a crucial role in many physiological processes, as well as potentially being biocompatible and capable of with biodegradation. As such, the purpose of the present study was to evaluate the in vivo performance of pure Zinc and Zn–2%Fe implants. The use of iron as an alloying element was aimed at accelerating the corrosion rate of pure zinc by a micro-galvanic effect so as to maintain the post-implantation biodegradation characteristics of the implant. In vivo assessment was carried out using cylindrical disks implanted in the back midline of 16 male Wistar rats for up to 24 weeks. Post-implantation evaluation included monitoring the well-being of rats, weekly examination of hematological parameters: serum Zn levels, red and white blood cell counts and hemoglobin levels, X-ray radiography, histological analysis and corrosion rate assessment. The results obtained in terms of well-being, hematological tests and histological analysis of the rats indicate that the in vivo behavior of pure Zn and Zn–2%Fe implants was adequate and in line with the results obtained by the control group containing inert Ti–6Al–4V alloy implants. The corrosion rate of Zn–2%Fe alloy in in vivo conditions was relatively increased compared to pure Zn due to micro-galvanic corrosion.

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High Performance Core/Shell Ni/Ni(OH)2 Electrospun Nanofiber Anodes for Decoupled Water Splitting

Decoupled water splitting is a promising new path for renewable hydrogen production, offering many potential advantages such as stable operation under partial-load conditions, high-pressure hydrogen production, overall system robustness, and higher safety levels. Here, the performance of electrospun core/shell nickel/nickel hydroxide anodes is demonstrated in an electrochemical-thermally activated chemical decoupled water splitting process. The high surface area of the hierarchical porous electrode structure improves the utilization efficiency, charge capacity, and current density of the redox anode while maintaining high process efficiency. The anodes reach average current densities as high as 113 mA cm⁻² at a working potential of 1.48 V_RHE and 64 mA cm⁻² at 1.43 V_RHE, with a Faradaic efficiency of nearly 100% and no H₂/O₂ intermixing in a membrane-free cell.     

Conductivity of a single DNA duplex bridging a carbon nanotube gap

We describe a general method to integrate DNA strands between single-walled carbon nanotube electrodes and to measure their electrical properties. We modified DNA sequences with amines on either the 5' terminus or both the 3' and 5' termini and coupled these to the single-walled carbon nanotube electrodes through amide linkages, enabling the electrical properties of complementary and mismatched strands to be measured. Well-matched duplex DNA in the gap between the electrodes exhibits a resistance on the order of 1 M(Omega). A single GT or CA mismatch in a DNA 15-mer increases the resistance of the duplex approximately 300-fold relative to a well-matched one. Certain DNA sequences oriented within this gap are substrates for Alu I, a blunt end restriction enzyme. This enzyme cuts the DNA and eliminates the conductive path, supporting the supposition that the DNA is in its native conformation when bridging the ends of the single-walled carbon nanotubes.     

Neuroprotective Effect of Glatiramer Acetate on Neurofilament Light Chain Leakage and Glutamate Excess in an Animal Model of Multiple Sclerosis

Axonal and neuronal pathologies are a central constituent of multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), induced by the myelin oligodendrocyte glycoprotein (MOG) 35–55 peptide. In this study, we investigated neurodegenerative manifestations in chronic MOG 35–55 induced EAE and the effect of glatiramer acetate (GA) treatment on these manifestations. We report that the neuronal loss seen in this model is not attributed to apoptotic neuronal cell death. In EAE-affected mice, axonal damage prevails from the early disease phase, as revealed by analysis of neurofilament light (NFL) leakage into the sera along the disease duration, as well as by immunohistological examination. Elevation of interstitial glutamate concentrations measured in the cerebrospinal fluid (CSF) implies that glutamate excess plays a role in the damage processes inflicted by this disease. GA applied as a therapeutic regimen to mice with apparent clinical symptoms significantly reduces the pathological manifestations, namely apoptotic cell death, NFL leakage, histological tissue damage, and glutamate excess, thus corroborating the neuroprotective consequences of this treatment.