Depression ratings, reported sexual risk behaviors, and methamphetamine use: Latent growth curve models of positive change among gay and bisexual men in an outpatient treatment program.

Although the cessation of substance use is the principal concern of drug treatment programs, many individuals in treatment experience co-occurring problems such as mood disruptions and sexual risk behaviors that may complicate their recovery process. This study assessed relationships among dynamic changes tracked over time in methamphetamine use, depression symptoms, and sexual risk behaviors (unprotected anal intercourse) in a sample of 145 methamphetamine-dependent gay and bisexual males enrolled in a 16-week outpatient drug treatment research program. Participants were randomly assigned into 1 of 4 conditions: contingency management (CM), cognitive behavioral therapy (CBT; the control condition), combined CM and CBT, and a tailored gay-specific version of the CBT condition. Using latent growth curve models, the authors assessed the relationship of means (intercepts) and the slopes of the 3 measures of interest over time to test whether changes in methamphetamine use predicted declining rates of depression and risky sexual behavior in tandem. Participants with the greatest downward trajectory in methamphetamine use (urine verified) reported the greatest and quickest decreases in reported depressive symptoms and sexual risk behaviors. The control group reported the most methamphetamine use over the 16 weeks; the tailored gay-specific group reported a more rapidly decreasing slope in methamphetamine use than the other participants. Findings indicate that lowering methamphetamine use itself has a concurrent and synergistic effect on depressive symptoms and risky sexual behavior patterns. This suggests that some users who respond well to treatment may show improvement in these co-occurring problems without a need for more intensive targeted interventions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the depth complexity of formulas

The problem of minimizing the depth of formulas by equivalence preserving transformations is formalized in a general algebraic setting. For a particular algebraic system ∑₀ specific methods of a dynamic programming nature are developed for proving lower bounds on depth. Such lower bounds for ∑₀ automatically imply the same results for the systems of (i) arithmetic computations with addition and multiplication only, and (ii) computations over finite languages using union and concatenation. The specific lower bounds obtained are (i) depth 2n?o(n) for the permanent, (ii) depth (0.25+o(1))log² n for the symmetric polynomials and (iii) depth 1.16logn for a problem of formula sizen.     

Embedding cryptographic trapdoors in arbitrary knapsack systems

In this paper we show that after sufficiently many modular multiplications, any knapsack system becomes a trapdoor system that can be used in public-key cryptography.     

Electrochemical Properties of La0.5Sr0.5Co0.8M0.2O3–δ (M=Mn,Fe, Ni,Cu) Perovskite Cathodes for IT‐SOFCs

The electrochemical properties of La_0.5Sr_0.5Co_0.8M_0.2O_3–δ (M=Mn, Fe, Ni, Cu) cathodes are investigated with chemical bulk diffusion coefficients (D_chem) and polarization resistances. The electrochemical performance of long‐term testing for La_0.5Sr_0.5Co_0.8Cu_0.2O_3–δ cathode was carried out to investigate its electrochemical stability. In this work, an anode‐supported single cell with a thick‐film SDC electrolyte (30 μm), a Ni‐SDC cermet anode (1 mm), and a La_0.5Sr_0.5Co_0.8Cu_0.2O_3–δ cathode (10 μm) reaches a maximum peak power density of 983 mW/cm² at 700°C. Obviously, Cu substitution for B‐site of La_0.5Sr_0.5CoO_3–δ cathode reduced thermal expansion coefficient (TEC) value and enhanced oxygen bulk diffusion and electrochemical properties. La_0.5Sr_0.5Co_0.8Cu_0.2O_3–δ is a promising cathode material for intermediate temperature solid oxide fuel cells (IT‐SOFC).     

Robust MIMO H∞ Integral-Backstepping PID Controller for Hovering Control of Unmanned Model Helicopter

The problem of stabilization of a model helicopter in a hover configuration subject to parametric uncertainty and external disturbances is addressed. Multiinput multioutput (MIMO) proportional-integral-derivative (PID) control law is reformulated into a full-state feedback control law to synthesize the controller by using robust H∞ control theory. In full-state feedback representation, PID control has implicit integral-backstepping structure. Therefore a new parameter, ρ, can be introduced that acts on the derivative of the control signal. The parameters of MIMO PID controller are then obtained with solving the algebraic Riccati equation with selecting the values of ρ and γ. Model helicopter simulation is carried out to verify the performance of the proposed controller to stabilize the uncertain helicopter model and to suppress external disturbances.     

A Practical-Time Related-Key Attack on the KASUMI Cryptosystem Used in GSM and 3G Telephony

Over the last 20 years, the privacy of most GSM phone conversations was protected by the A5/1 and A5/2 stream ciphers, which were repeatedly shown to be cryptographically weak. They are being replaced now by the new A5/3 and A5/4 algorithms, which are based on the block cipher KASUMI. In this paper we describe a new type of attack called a sandwich attack, and use it to construct a simple related-key distinguisher for 7 of the 8 rounds of KASUMI with an amazingly high probability of 2^?14. By using this distinguisher and analyzing the single remaining round, we can derive the complete 128-bit key of the full KASUMI with a related-key attack which uses only 4 related keys, 2²⁶ data, 2³⁰ bytes of memory, and 2³² time. These completely practical complexities were experimentally verified by performing the attack in less than two hours on a single-core of a PC. Interestingly, neither our technique nor any other published attack can break the original MISTY block cipher (on which KASUMI is based) significantly faster than exhaustive search. Our results thus indicate that the modifications made by ETSI’s SAGE group in moving from MISTY to KASUMI made it extremely weak when related-key attacks are allowed, but do not imply anything about its resistance to single-key attacks. Consequently, there is no indication that the way KASUMI is implemented in GSM and 3G networks is practically vulnerable in any realistic attack model.     

Immobilization of Co(III) using tethered cyclam ligand on SBA-15 mesoporous silica for aerial oxidation of ethylbenzene

Cyclam type macrocyclic ligand was tethered onto mesoporous silica surface through N-functionalization of the cyclam. The mesoporous silica was synthesized directly with in-built chloropropyl functional group by applying microwave synthesis approach and the cyclam ligand was tethered via the surface substitution reaction of the chloro group. The tethered cyclam ligand was proven to facilely accommodate Co(III) cation into its cavity. This Co(III)cyclam-functionalized mesoporous silica showed good catalytic activity in the aerial oxidation of ethylbenzene to give acetophenone as the major product, which exceeded 60%. The presence of pyridine ligand which bounded to the axial sites of the tethered Co(III)cyclam complex enhanced the activity of the catalyst with sustaining the selectivity.     

Computing Derivatives of Noisy Signals Using Orthogonal Functions Expansions

In many applications noisy signals are measured. These signals have to be filtered and, sometimes, their derivative has to be computed. In this paper a method for filtering the signals and computing the derivatives is presented. This method is based on expansion onto transformed Legendre polynomials. Numerical examples demonstrate the efficacy of the method as well as the theoretical estimates. This research was supported by the ISRAEL SCIENCE FOUNDATION (grant No. 1364/04) and the UNITED STATES-ISRAEL BINATIONAL SCIENCE FOUNDATION (grant No. 2004099).