NMDA receptor antagonists impair prefrontal cortex function as assessed via spatial delayed alternation performance in rats: modulation by dopamine

The present study was performed to assess the role of excitatory amino acid and dopamine receptors on associative functions of the prefrontal cortex (PFC) of the rat. Spatial delayed alternation was used as a PFC-sensitive cognitive task. In addition, in vivo microdialysis was used to assess the release of dopamine in the PFC. The noncompetitive NMDA antagonists ketamine (10-30 mg/kg) and MK-801 (0.1 and 0.5 mg/kg) dose-dependently impaired the spatial delayed alternation performance compared with the saline-treated control group. Administration of the dopamine antagonists raclopride (0.1 and 0.5 mg/kg), SCH-23390 (0.1 mg/kg), or haloperidol (0.1 mg/kg) was without a significant effect. However, haloperidol and raclopride (but not SCH-23390) reversed the disruptive effect of 30 mg/kg ketamine on spatial delayed alternation performance. Microdialysis studies revealed that this dose of ketamine preferentially increased the release of dopamine in the PFC compared with the striatum. These findings indicate that attenuation of glutamatergic neurotransmission at the NMDA receptor impairs PFC-dependent cognitive functions. Furthermore, activation of dopamine neurotransmission contributes, at least in part, to this impairment.     

Psychological Processes and "The Staircase to Terrorism"

Replies to the comments of Paniagua (see record 2005-15840-016) and Steiner (see record 2005-15840-015) on his original article (see record 2005-01817-002) on terrorism. The author notes that several points raised by Paniagua and Steiner are insightful and help to broaden the range of factors to be considered on the staircase to terrorism. Steiner highlights the role of incitement, and this points to the importance of both research and policies for better understanding, monitoring, and combating voices for hate. Paniagua points out that a number of extremist leaders are not open to negotiation, suggesting that when attempting negotiation with individuals who have reached the final levels of the staircase to terrorism, authorities must selectively try different policies with different terrorist groups and leaders. The author also notes that a subtle but profound theme links the other major points made by the two: that Islamic terrorism is different and has to be treated as a separate phenomenon. Steiner implies this with reference to what he sees as a long history of conflict between the West and the Islamic World; Paniagua suggests this by placing terrorism by various major "terrorist organizations" in the category of political terrorism and depicting political terrorism as different from Islamic terrorism. Both of these observations are intriguing, but they should not distract psychologists from the foundational psychological processes that underlie terrorist thought and action. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perfect load balancing on the star interconnection network

In this paper, we use the regular distribution method to design a perfect load balancing algorithm for an n-star with a maximum error of 1 and a time complexity of 3n(n+1). This algorithm is based on the novel notion of leader trees. A second algorithm proposed in this paper as an enhancement to our first algorithm and uses an arbitrary spanning tree as the leader tree and has a worst time complexity of 2.25n ²−3n+0.75. We also discuss the issue of dynamically selecting the leader tree and hybrid load balancing algorithms in general. Furthermore, we present a hybrid algorithm for load balancing on the star interconnection network which benefits from a diffusion load balancing preprocessing phase and shows a smaller mean time complexity than our two first algorithms.     

A novel evolutionary approach for optimizing content-based image indexing algorithms.

Optimization of content-based image indexing and retrieval (CBIR) algorithms is a complicated and time-consuming task since each time a parameter of the indexing algorithm is changed, all images in the database should be indexed again. In this paper, a novel evolutionary method called evolutionary group algorithm (EGA) is proposed for complicated time-consuming optimization problems such as finding optimal parameters of content-based image indexing algorithms. In the new evolutionary algorithm, the image database is partitioned into several smaller subsets, and each subset is used by an updating process as training patterns for each chromosome during evolution. This is in contrast to genetic algorithms that use the whole database as training patterns for evolution. Additionally, for each chromosome, a parameter called age is defined that implies the progress of the updating process. Similarly, the genes of the proposed chromosomes are divided into two categories: evolutionary genes that participate to evolution and history genes that save previous states of the updating process. Furthermore, a new fitness function is defined which evaluates the fitness of the chromosomes of the current population with different ages in each generation. We used EGA to optimize the quantization thresholds of the wavelet-correlogram algorithm for CBIR. The optimal quantization thresholds computed by EGA improved significantly all the evaluation measures including average precision, average weighted precision, average recall, and average rank for the wavelet-correlogram method.     

Regions-of-Interest and Spatial Layout for Content-Based Image Retrieval

To date most content-based image retrieval (CBIR) techniques rely on global attributes such as color or texture histograms which tend to ignore the spatial composition of the image. In this paper, we present an alternative image retrieval system based on the principle that it is the user who is most qualified to specify the query content and not the computer. With our system, the user can select multiple regions-of-interest and can specify the relevance of their spatial layout in the retrieval process. We also derive similarity bounds on histogram distances for pruning the database search. This experimental system was found to be superior to global indexing techniques as measured by statistical sampling of multiple users' satisfaction ratings.     

A Novel Benzocyclobutene-Based Device for Studying the Dynamics of Heat Transfer During the Nucleation Process

A novel microelectromechanical device has been developed to study the details of the heat transfer mechanisms involved at the nucleation site for the nucleate boiling process. This device enables quantifying the magnitude, time period of activation, and specific areas of influence of different mechanisms of heat transfer from the surface with a resolution several times greater than previously reported. This is achieved through the use of an array of embedded temperature sensors within a carefully designed dual-layer (silicon and benzocyclobutene) wall which allows for the accurate calculation of local heat flux, circumventing difficulties encountered when using existing methods. The sensors are radially distributed around the nucleation site. Heat is supplied to the wall by a thin film heater fabricated on the outer nonwetted surface. Single bubbles are generated at the center of the array while the temperatures and the bubble images are recorded with a sampling frequency of 8 kHz. The temperature data provided the necessary thermal boundary conditions to numerically calculate the surface heat flux with an unprecedented radial resolution of 22-40 mum. Fabrication, characterization, and the ability of the developed device to elucidate the heat transfer aspects of the nucleation process are demonstrated.     

Sound absorption characteristics of needle-punched sustainable Typha /polypropylene non-woven

Natural fibers are the acoustical sustainable materials used in blends with polypropylene as carded needle-punched non-woven for the automobile industry. Among the variety of natural fibers, studying the noise-absorptive properties of a novelty introduced fiber called Leafiran extracted from the Typha Australis plant has been aimed in this paper. Typha natural fibers were blended with polypropylene fibers in order to investigate the effect of this newly known natural fiber on the acoustic performance of producing non-woven composite structures. For this aim, five different blend ratios of Typha/polypropylene including 0:100, 30:70, 50:50, 70:30, and 100:0 were prepared. The non-woven porosity, areal density, and sound absorption properties were studied. Impedance Tube Method, which provides the normal incidence sound absorption coefficient (SAC) of materials, was used for determining the acoustic properties of produced non-woven samples. The results of SACs of Typha non-woven revealed that the Typha fibers have good acoustic performance with normal incidence absorption coefficient greater than 0.6 from 500 to 4 kHz. Finally, according to the obtained results from this research, it is claimed that Typha natural fibers could be an acceptable choice for sound reduction applications.     

New formulation for the simulation of the conjugate heat transfer at the curved interfaces based on the ghost fluid lattice Boltzmann method

ABSTRACT

In the present study, a new method for simulation of the conjugate heat transfer conditions at the curved interface of two media with different thermal properties is proposed based on the ghost fluid lattice Boltzmann method (GF-LBM). The proposed method significantly benefits from the inherent feature of the GF-LBM in availability of the temperature gradient normal to the interface. To test the accuracy of the presented method, three different case studies are simulated. The results revealed the second-order accuracy of the proposed conjugate heat transfer formulation. Furthermore, when compared to the available analytical solutions, the results of this study showed better agreement compared to the results of the other available methods.     

Lyotropic liquid crystalline self-assembly material behavior and nanoparticulate dispersions of a phytanyl pro-drug analogue of capecitabine-a chemotherapy agent

An amphiphile prodrug, 5'-deoxy-5-fluoro-N?-(phytanyloxycarbonyl) cytidine (5-FCPhy) has been prepared and investigated for its self-assembly material properties, in vitro cytotoxicity, and in vivo efficacy as a chemotherapy agent. The phase transitions and stability of the neat amphiphile were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). X-ray diffraction (XRD) was used to confirm the structure of the neat amphiphile, which was an amorphous glassy material. The lyotropic liquid crystalline self-assembly behavior of the amphiphile prodrug in water was examined by cross polarizing optical microscopy (POM) and small-angle X-ray scattering (SAXS). Under excess water conditions at room temperature, the amphiphile prodrug self-assembles into lyotropic liquid crystalline mesophases of inverse bicontinuous cubic symmetry. Upon aging, the inverse cubic phase slowly transformed to an inverse hexagonal phase. This amphiphile was successfully dispersed into nanoparticles of cubic and hexagonal symmetry. The in vitro cytotoxicity of dispersed nanoparticles was evaluated in seven different normal and cancer cell types and exhibited IC?? values between 70 and 90 μM for all cell types. Evaluation of 5-FCPhy in vivo against a mouse 4T1 breast tumor model displayed a trend of increasing efficacy with increasing dose. Furthermore, after 21 days, tumor volumes in the 0.5 mmol 5-FCPhy treatment group were significantly smaller than all other treatment groups including mice receiving a short chain water-soluble analogue, Capecitabine (a commercially available oral chemotherapy agent), delivered at the same dosage.