bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of GluR1 expression in nucleus accumbens neurons in cocaine sensitization and cocaine‐seeking behavior
Authors: Bachtell Ryan K. , Choi Kwang‐Ho , Simmons Diana L. , Falcon Edgardo , Monteggia Lisa M. , Neve Rachael L. , Self David W.
Published: April 2008

Chronic cocaine use reduces glutamate levels in the nucleus accumbens (NAc), and is associated with experience‐dependent changes in (±)‐α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionic acid (AMPA) glutamate receptor membrane expression in NAc neurons. These changes accompany behavioral sensitization to cocaine and increased susceptibility to cocaine relapse. The functional relationship between neuroplasticity in AMPA receptors and the behavioral manifestation of cocaine addiction remains unclear. Thus, we examined the behavioral effects of up‐ and downregulating basal AMPA receptor function in the NAc core and shell using viral‐mediated gene transfer of wild‐type glutamate receptor 1 (wt‐GluR1) or a dominant‐negative pore‐dead GluR1 (pd‐GluR1), respectively. Transient increases in wt‐GluR1 during or after cocaine treatments diminished the development of cocaine sensitization, while pd‐GluR1 expression exacerbated cocaine sensitization. Parallel changes were found in D2, but not D1, receptor‐mediated behavioral responses. As a correlate of the sensitization experiments, we overexpressed wt‐ or pd‐GluR1 in the NAc core during cocaine self‐administration, and tested the effects on subsequent drug‐seeking behavior 3 weeks after overexpression declined. wt‐GluR1 overexpression during self‐administration had no effect on cocaine intake, but subsequently reduced cocaine seeking in extinction and cocaine‐induced reinstatement, whereas pd‐GluR1 facilitated cocaine‐induced reinstatement. When overexpressed during reinstatement tests, wt‐GluR1 directly attenuated cocaine‐ and D2 agonist‐induced reinstatement, while pd‐GluR1 enhanced reinstatement. In both experimental procedures, neither wt‐ nor pd‐GluR1 expression affected cue‐induced reinstatement. Together, these results suggest that degrading basal AMPA receptor function in NAc neurons is sufficient to facilitate relapse via sensitization in D2 receptor responses, whereas elevating basal AMPA receptor function attenuates these behaviors.
Movement‐related synchronization of gamma activity is lateralized in patients with dystonia
Authors: Brücke Christof , Kempf Florian , Kupsch A. , Schneider Gerd‐Helge , Krauss Joachim K. , Aziz Tipu , Yarrow Kielan , Pogosyan Alek , Brown Peter , Kühn Andrea A.
Published: April 2008

There is evidence for synchronization at frequencies both under 30 Hz and over 60–80 Hz in the so‐called gamma frequency band in patients with Parkinson's disease (PD). Gamma activity increases after dopaminergic therapy and during voluntary movement, suggesting that it might be physiological and relate to motor processing in the basal ganglia (BG). We recorded local field potential (LFP) activity during a choice reaction time task in 11 patients with dystonia undergoing implantation of the internal globus pallidus for therapeutic stimulation. The spectral content of the LFP was averaged with respect to movement onset over 6–11 Hz, 18–25 Hz and 60–80 Hz, separately for responses ipsilateral and contralateral to movement. There was a perimovement increase in 60–80 Hz activity in the LFP, but only contralateral to movement. In contrast, low‐frequency LFP activity decreased symmetrically during movement. This occurred earlier in the 18–25 Hz band than in the 6–11 Hz band, and was followed by a postmovement increase in oscillatory activity in the 18–25 Hz band that was contralateral to movement. The presence of a lateralized movement‐related increase in gamma activity in the BG of patients with dystonia, similar to that recorded in patients with treated PD, suggests that this may be a residual feature of normal BG function. Moreover, the results provide further support for functional distinctions between BG oscillatory activities of different frequency.
Ant predation on red oak borer confirmed by field observation and molecular gut‐content analysis
Authors: Muilenburg Vanessa L. , Goggin Fiona L. , Hebert Stephanie L. , Jia Lingling , Stephen Fred M.
Published: April 2008

1 Populations of an indigenous longhorn beetle, the red oak borer Enaphalodes rufulus (Haldeman) (Coleoptera: Cerambycidae), recently reached epidemic levels in the Ozark National Forests of Arkansas and Missouri, resulting in extensive tree mortality.

2 The factors regulating E. rufulus populations are largely unknown. Ants appear to be the most abundant potential predators in the Ozarks and have been shown to play a role in regulating populations of other forest insects.

3 The main objective of the present study was to determine whether ants are predators of early E. rufulus life stages by direct observation of E. rufulus eggs artificially placed on tree trunks and by development of molecular tools to detect E. rufulus DNA within ant gut contents.

4 Three hundred and eighty E. rufulus eggs were applied to ten northern red oaks. Ants ate or carried away 72% of the eggs within 1 h. Camponotus pennsylvanicus (De Geer) and Aphaenogaster tennesseensis (Mayr) were identified as the two primary ant species observed in the study.

5 A portion of the mitochondrial 16S rRNA gene of E. rufulus was sequenced and polymerase chain reaction primers were developed to detect E. rufulus DNA in the guts of C. pennsylvanicus. Enaphalodes rufulus DNA persisted in ant gut contents for at least 24 h after ingestion under laboratory conditions, and E. rufulus DNA was detected in field‐collected ant populations, suggesting the natural occurrence of ant predation on this insect.
Field‐based and laboratory stable isotope probing surveys of the identities of both aerobic and anaerobic benzene‐metabolizing microorganisms in freshwater sediment
Authors: Liou J. S.‐C. , DeRito C. M. , Madsen E. L.
Published: April 2008

Laboratory incubations of coal‐tar waste‐contaminated sediment microbial communities under relatively controlled physiological conditions were used to interpret results of a field‐based stable isotope probing (SIP) assay. Biodegradation activity of 13C‐benzene was examined by GC/MS determination of net 13CO2 production and by GC headspace analysis of benzene loss. Key experimental variables were: the site of the assays (laboratory serum‐bottle incubations and in situ field sediments), benzene concentration (10, 36 or 200 p.p.m. in laboratory assays), and physiological conditions (anaerobic with or without sulfate or nitrate additions versus aerobic headspace or the uncontrolled field). In anaerobic laboratory incubations of benzene at 10 p.p.m., greater than 60% of the substrate was eliminated within 15 days. During anaerobic incubations of 200 p.p.m. benzene (70 days), 0.9% benzene mineralization occurred. When benzene (36 p.p.m.) was added to sediment with air in the serum‐bottle headspace, 14% of the initial 13C was mineralized to 13CO2 in 2.5 days. In the field experiment (178 μg 13C‐benzene dosed to undisturbed sediments), net 13CO2 production reached 0.3% within 8.5 h. After isopycnic separation of 13C (heavy)‐labelled DNA from the above biodegradation assays, sequencing of 13C‐DNA clone libraries revealed a broad diversity of taxa involved in benzene metabolism and distinctive libraries for each biodegradation treatment. Perhaps most importantly, in the field SIP experiment the clone libraries produced were dominated by Pelomonas (betaproteobacteria) sequences similar to those found in the anaerobic 10 p.p.m. benzene laboratory experiment. These data indicate that the physiological conditions that prevail and govern in situ biodegradation of pollutants in the field may be interpreted by knowing the physiological preferences of potentially active populations.
Phytophthora parasitica biofilm formation: installation and organization of microcolonies on the surface of a host plant
Authors: Galiana Eric , Fourré Sandra , Engler Gilbert
Published: April 2008

Zoospores of the oomycete Phytophthora parasitica establish microbial spheroid microcolonies and biofilms on the surface of wounded leaves of their host, Nicotiana tabacum. The formation of microcolonies involves the movement of some zoospores towards attractants from wound sites, followed by their irreversible adsorption and the formation of a cluster of cells. These cells drive the migration of a second wave of zoospores (several hundreds cells) by setting up an external chemotactic gradient leading to massive zoospore encystment and cyst‐orientated germination. Zoospores that are still swimming at this stage circulate within the nascent biofilm by opening channels. Concomitantly, the cell population secretes various substances to elaborate an extracellular mucilage. Embedded within the extracellular matrix, biofilm cells are organized into a structured community as coacervates. The granular surface is composed of individual cysts, located on the outside of the microcolony. Hyphae from these cysts plunge downwards towards the dense core formed by the founder cells. This report is the first to show the installation and organization of a biofilm formed by eukaryotic cells on plant surfaces. The P. parasitica microcolonies constitute heterogeneous microenvironments for the embedded and circulating cells. They may affect plant–pathogen interactions by serving as reservoirs for pathogenic microorganisms, as protecting niche against host defences or as structures for infecting populations.
Feline early life ocular disease
Authors: Jacobi Susan , Dubielzig Richard R.
Published: April 2008

Objectives   Histomorphologic changes in six globes from six cats, which experienced early life ocular disease of undetermined etiology, are described.

Design   A retrospective morphologic study of six eyes from six cats with early life ocular surface disease of unknown etiology, from 2002 to 2006 extracted from a pathology collection, which includes 2200 feline submissions.

Procedure   Sections of affected globes, stained with H&E were examined with a light microscope.

Results   The mean age of the affected cats, at the time of enucleation, was 7.5 months ranging from 7 weeks to 2 years. The cats were one male, one female, one male neutered, and one female spayed cat. For the remaining two cats the sex was not known. All cats were DSH. Significant histomorphologic findings included collapse of the globe in all cases and a broad corneal perforation with protrusion of the anterior uvea, which was epithelialized in all cases. Three cases revealed uveal hematopoiesis in the anterior and posterior uvea. All cases had recognizable corneal tissue at the limbus on both sides. Inflammation in all cases consisted of variable but generally mild uveitis and no eyes had endophthalmitis. Four of the globes had no recognizable lens tissue. Three of the cats had symblepharon formation described as part of the clinical condition. The other three cases had no mention of symblepharon.

Conclusions   These cases are considered to represent changes associated with early life corneal ablation of unknown etiology. Uveal prolapse, mild inflammation, and symblepharon are considered to be either secondary or caused by the same destructive primary event that affected the cornea. These cases are the first cases we are aware of with uveal extramedullary hematopoiesis in cats. Careful consideration of cell morphology is necessary to distinguish this condition from round cell neoplasms or inflammation.
Positive surgical margins during robotic radical prostatectomy: a contemporary analysis of risk factors
Authors: Liss Michael , Osann Kathryn , Ornstein David
Published: April 2008

OBJECTIVE

To determine the risk factors (clinical, pathological and technical) for positive surgical margins (PSMs) after robotically assisted radical prostatectomy (RARP), as a PSM is associated with an increased risk of biochemical recurrence and often responsible for significant patient anxiety.

PATIENTS AND METHODS

Between November 2003 and March 2007, 216 consecutive patients had an RARP by one fellowship‐trained urological oncologist. The surgical pathological specimens were fixed and processed using standard techniques, and assessed by a pathologist at the same institution. A PSM was defined as the presence of cancer adjacent to the inked margin. The clinical charts were reviewed retrospectively under an approved institutional review board protocol. Univariable and multivariable methods, including logistic regression models, were used to analyse the clinical, pathological and technical risk factors for PSM.

RESULTS

The overall prevalence of PSM was 14.8% (32/216), and 5.4% (8/149) for pT2 cancers. The only preoperative factor that was associated with a greater risk of a PSM was the serum prostate‐specific antigen (PSA) level (P = 0.012) and PSA density (P = 0.005). Age, clinical stage and clinical Gleason grade were not predictors of a PSM. The overall and pT2 PSM rate remained constant throughout the series of 216 patients (P = 0.371), indicating that the initial experience for RARP was not associated with a significantly greater risk of a PSM. However, there was a small independent ‘learning curve’ effect, with a lower rate of PSM associated with each increment of 25 patients (odds ratio 0.8, 95% confidence interval 0.6–1.0), supported by the significantly decreasing trend in PSM for pT3 cancers over time (P = 0.031) Although there was no significant increase over time in PSM with the use of an endostapler to control the dorsal venous complex (DVC), there was a significant learning effect, with a decrease in the PSM rate specifically in pT3 cancers using the suture technique (P = 0.005). A nerve‐sparing procedure increased the risk of PSM in multivariable analysis (P = 0.03). As expected, pathological stage and pathological Gleason grade were the strongest predictors of PSM (P < 0.001).

CONCLUSION

The most important risk factors for a PSM after RARP are the preoperative PSA level, PSA density, pathological stage and Gleason grade. PSM rates for a surgeon in their initial experience can be comparable to that of a surgeon experienced in RARP. Using a stapling device to control the DVC does not appear to increase the risk of a PSM, although nerve‐sparing increases the rates of PSM in extraprostatic prostate cancer.
The greening and browning of Alaska based on 1982–2003 satellite data
Authors: Verbyla David
Published: April 2008

Aim To examine the trends of 1982–2003 satellite‐derived normalized difference vegetation index (NDVI) values at several spatial scales within tundra and boreal forest areas of Alaska.

Location Arctic and subarctic Alaska.

Methods Annual maximum NDVI data from the twice monthly Global Inventory Modelling and Mapping Studies (GIMMS) NDVI 1982–2003 data set with 64‐km2pixels were extracted from a spatial hierarchy including three large regions: ecoregion polygons within regions, ecozone polygons within boreal ecoregions and 100‐km climate station buffers. The 1982–2003 trends of mean annual maximum NDVI values within each area, and within individual pixels, were computed using simple linear regression. The relationship between NDVI and temperature and precipitation was investigated within climate station buffers.

Results  At the largest spatial scale of polar, boreal and maritime regions, the strongest trend was a negative trend in NDVI within the boreal region. At a finer scale of ecoregion polygons, there was a strong positive NDVI trend in cold arctic tundra areas, and a strong negative trend in interior boreal forest areas. Within boreal ecozone polygons, the weakest negative trends were from areas with a maritime climate or colder mountainous ecozones, while the strongest negative trends were from warmer basin ecozones. The trends from climate station buffers were similar to ecoregion trends, with no significant trends from Bering tundra buffers, significant increasing trends among arctic tundra buffers and significant decreasing trends among interior boreal forest buffers. The interannual variability of NDVI among the arctic tundra buffers was related to the previous summer warmth index. The spatial pattern of increasing tundra NDVI at the pixel level was related to the west‐to‐east spatial pattern in changing climate across arctic Alaska. There was no significant relationship between interannual NDVI and precipitation or temperature among the boreal forest buffers. The decreasing NDVI trend in interior boreal forests may be due to several factors including increased insect/disease infestations, reduced photosynthesis and a change in root/leaf carbon allocation in response to warmer and drier growing season climate.

Main conclusions There was a contrast in trends of 1982–2003 annual maximum NDVI, with cold arctic tundra significantly increasing in NDVI and relatively warm and dry interior boreal forest areas consistently decreasing in NDVI. The annual maximum NDVI from arctic tundra areas was strongly related to a summer warmth index, while there were no significant relationships in boreal areas between annual maximum NDVI and precipitation or temperature. Annual maximum NDVI was not related to spring NDVI in either arctic tundra or boreal buffers.
The lack of a systematic validation of reference genes: a serious pitfall undervalued in reverse transcription‐polymerase chain reaction (RT‐PCR) analysis in plants
Authors: Gutierrez Laurent , Mauriat Mélanie , Guénin Stéphanie , Pelloux Jérôme , Lefebvre Jean‐François , Louvet Romain , Rusterucci Christine , Moritz Thomas , Guerineau François , Bellini Catherine , Van Wuytswinkel Olivier
Published: April 2008

Reverse transcription‐polymerase chain reaction (RT‐PCR) approaches have been used in a large proportion of transcriptome analyses published to date. The accuracy of the results obtained by this method strongly depends on accurate transcript normalization using stably expressed genes, known as references. Statistical algorithms have been developed recently to help validate reference genes, and most studies of gene expression in mammals, yeast and bacteria now include such validation. Surprisingly, this important approach is under‐utilized in plant studies, where putative housekeeping genes tend to be used as references without any appropriate validation. Using quantitative RT‐PCR, the expression stability of several genes commonly used as references was tested in various tissues of Arabidopsis thaliana and hybrid aspen (Populus tremula × Populus tremuloides). It was found that the expression of most of these genes was unstable, indicating that their use as references is inappropriate. The major impact of the use of such inappropriate references on the results obtained by RT‐PCR is demonstrated in this study. Using aspen as a model, evidence is presented indicating that no gene can act as a universal reference, implying the need for a systematic validation of reference genes. For the first time, the extent to which the lack of a systematic validation of reference genes is a stumbling block to the reliability of results obtained by RT‐PCR in plants is clearly shown.
Conditional Belonging: Farm Workers and the Cultural Politics of Recognition in Zimbabwe
Authors: Rutherford Blair
Published: April 2008

This article examines Zimbabwean land politics and the study of rural interventions, including agrarian reform, more broadly, using the analytical framework of territorialized ‘modes of belonging’ and their ‘cultural politics of recognition’. Modes of belonging are the routinized discourses, social practices and institutional arrangements through which people make claims for resources and rights, the ways through which they become ‘incorporated’ in particular places. In these spatialized forms of power and authority, particular cultural politics of recognition operate; these are the cultural styles of interaction that become privileged as proper forms of decorum and morality informing dependencies and interdependencies. The author traces a hegemonic mode of belonging identified as ‘domestic government’, put in place on European farms in Zimbabwe's colonial period, and shows how it was shaped by particular political and economic conjunctures in the first twenty years of Independence after 1980. Domestic government provided a conditional belonging for farm workers in terms of claims to limited resources on commercial farms while positioning them in a way that made them marginal citizens in the nation at large. This is the context for the behaviour of land‐giving authorities which have actively discriminated against farm workers during the politicized and violent land redistribution processes that began in 2000. Most former farm workers are now seeking other forms of dependencies, typically more precarious and generating fewer resources and services than they had accessed on commercial farms, with their own particular cultural politics of recognition, often tied to demonstrating support to the ruling political party.
Explaining the Failure of Thailand's Anti‐corruption Regime
Authors: Mutebi Alex M.
Published: April 2008

Despite the presence of strong anti‐corruption policies, state and regulatory capture may persist and thrive in the highest echelons of government. This article explores such a case, that of Thailand under former Prime Minister, Thaksin Shinawatra. The author argues that the primary explanation for this contradiction lies in Thailand's post‐1997 anti‐corruption framework. Because of the ascendancy of a business–politics nexus more powerful in blocking reform than Thai constitutional drafters had anticipated, and because of the decline in political contestability as a result of Thaksin's control of both the legislature and the executive, the stage was set for a dramatic increase in the levels of state capture. The author suggests that effective control of such political corruption calls for a strategy which extends far beyond the technocratic approaches used by Thai reformers in the mid to late 1990s.
Corruption in emergency procurement
Authors: Schultz Jessica , Søreide Tina
Published: April 2008

Corruption in emergency procurement reduces the resources available for life‐saving operations, lowers the quality of products and services provided, and diverts aid from those who need it most.1 It also negatively influences public support for humanitarian relief, both in the affected country and abroad. This paper aims to unpack and analyse the following question in order to mitigate risk: how and where does corruption typically occur, and what can be done? Suggested strategies reflect a multi‐layered approach that stresses internal agency control mechanisms, conflict‐sensitive management, and the need for common systems among operators.
THE AGRICULTURAL TERMS OF TRADE IN BANGLADESH: AN ECONOMETRIC ANALYSIS OF TRENDS AND MOVEMENTS, 1952–2006
Authors: AKHTAR HOSSAIN AKHAND
Published: April 2008

This paper investigates the trends and movements of agricultural prices, industrial prices and the agricultural terms of trade in Bangladesh with annual data for the period 1952–2006. The ADF and KPSS tests results suggest that both agricultural and industrial prices have a unit root while the agricultural terms of trade is trend‐stationary. These results remain unchanged if allowance is made in the unit root test for the possibility of a structural break during 1971–1975 (when Bangladesh gained independence from Pakistan and experienced economic shocks) by applying the two‐step procedure of Perron (1989). A simple Nerlovian agricultural price determination model is specified within the framework of aggregate demand and aggregate supply. The Johansen cointegration test results for the periods 1953–2006 and 1973–2006 suggest that there exists a cointegral relationship between agricultural prices, industrial prices, per‐capita real income and the real exchange rate between the Bangladeshi taka and the US dollar under the restriction that per‐capita real income and the real exchange rate are ‘long‐run forcing variables’ in the sense of Pesaran and Shin (1995), and Pesaran, Shin and Smith (1996). The paper estimates a four‐variable vector error‐correction (VEC) model and conducts an impulse response analysis for the post‐independence period, 1973–2006.
A MACROECONOMIC PERSPECTIVE ON SKILL SHORTAGES AND THE SKILL PREMIUM IN NEW ZEALAND*
Authors: RAZZAK WESHAH A. , TIMMINS JASON C.
Published: April 2008

Qualification and occupation‐based measures of skilled labour are constructed to explain the skill premium – the wage of skilled labour relative to unskilled labour in New Zealand. The data exhibit a more rapid growth in the supply of skilled labour than the skill premium, and a very large increase in the real minimum wage over the period from 1986 to 2005. We estimate the rate of increase in the relative demand for skills and the elasticity of substitution. The data are consistent with skill shortages and a skill‐bias technical change. We examine the effects of the minimum wage, capital complementarity, and the exchange rate on the skill premium. We also test whether the demand for skills and the elasticity of substitution varied across industries and over time.
Reduced Depth and Visual Hulls of Complex 3D Scenes
Authors: Bogomjakov Alexander , Gotsman Craig
Published: April 2008

Depth and visual hulls are useful for quick reconstruction and rendering of a 3D object based on a number of reference views. However, for many scenes, especially multi‐object, these hulls may contain significant artifacts known as phantom geometry. In depth hulls the phantom geometry appears behind the scene objects in regions occluded from all the reference views. In visual hulls the phantom geometry may also appear in front of the objects because there is not enough information to unambiguously imply the object positions.

In this work we identify which parts of the depth and visual hull might constitute phantom geometry. We define the notion of reduced depth hull and reduced visual hull as the parts of the corresponding hull that are phantom‐free. We analyze the role of the depth information in identification of the phantom geometry. Based on this, we provide an algorithm for rendering the reduced depth hull at interactive frame‐rates and suggest an approach for rendering the reduced visual hull. The rendering algorithms take advantage of modern GPU programming techniques.

Our techniques bypass explicit reconstruction of the hulls, rendering the reduced depth or visual hull directly from the reference views.
Effect of Character Animacy and Preparatory Motion on Perceptual Magnitude of Errors in Ballistic Motion
Authors: Reitsma P. S. A. , Andrews J. , Pollard N. S.
Published: April 2008

An increasing number of projects have examined the perceptual magnitude of visible artifacts in animated motion. These studies have been performed using a mix of character types, from detailed human models to abstract geometric objects such as spheres. We explore the extent to which character morphology influences user sensitivity to errors in a fixed set of ballistic motions replicated on three different character types. We find user sensitivity responds to changes in error type or magnitude in a similar manner regardless of character type, but that users display a higher sensitivity to some types of errors when these errors are displayed on more human‐like characters. Further investigation of those error types suggests that being able to observe a period of preparatory motion before the onset of ballistic motion may be important. However, we found no evidence to suggest that a mismatch between the preparatory phase and the resulting ballistic motion was responsible for the higher sensitivity to errors that was observed for the most humanlike character.
CHC++: Coherent Hierarchical Culling Revisited
Authors: Mattausch Oliver , Bittner Jiří , Wimmer Michael
Published: April 2008

We present a new algorithm for efficient occlusion culling using hardware occlusion queries. The algorithm significantly improves on previous techniques by making better use of temporal and spatial coherence of visibility. This is achieved by using adaptive visibility prediction and query batching. As a result of the new optimizations the number of issued occlusion queries and the number of rendering state changes are significantly reduced. We also propose a simple method for determining tighter bounding volumes for occlusion queries and a method which further reduces the pipeline stalls. The proposed method provides up to an order of magnitude speedup over the previous state of the art. The new technique is simple to implement, does not rely on hardware calibration and integrates well with modern game engines.
Augmented Panoramic Video
Authors: Hermans C. , Vanaken C. , Mertens T. , Van Reeth F. , Bekaert P.
Published: April 2008

Many video sequences consist of a locally dynamic background containing moving foreground subjects. In this paper we propose a novel way of re‐displaying these sequences, by giving the user control over a virtual camera frame. Based on video mosaicing, we first compute a static high quality background panorama. After segmenting and removing the foreground subjects from the original video, the remaining elements are merged into a dynamic background panorama, which seamlessly extends the original video footage. We then re‐display this augmented video by warping and cropping the panorama. The virtual camera can have an enlarged field‐of‐view and a controlled camera motion. Our technique is able to process videos with complex camera motions, reconstructing high quality panoramas without parallax artefacts, visible seams or blurring, while retaining repetitive dynamic elements.
Zippy: A Framework for Computation and Visualization on a GPU Cluster
Authors: Fan Zhe , Qiu Feng , Kaufman Arie E.
Published: April 2008

Due to its high performance/cost ratio, a GPU cluster is an attractive platform for large scale general‐purpose computation and visualization applications. However, the programming model for high performance general‐purpose computation on GPU clusters remains a complex problem. In this paper, we introduce the Zippy frame‐work, a general and scalable solution to this problem. It abstracts the GPU cluster programming with a two‐level parallelism hierarchy and a non‐uniform memory access (NUMA) model. Zippy preserves the advantages of both message passing and shared‐memory models. It employs global arrays (GA) to simplify the communication, synchronization, and collaboration among multiple GPUs. Moreover, it exposes data locality to the programmer for optimal performance and scalability. We present three example applications developed with Zippy: sort‐last volume rendering, Marching Cubes isosurface extraction and rendering, and lattice Boltzmann flow simulation with online visualization. They demonstrate that Zippy can ease the development and integration of parallel visualization, graphics, and computation modules on a GPU cluster.
Texture Synthesis From Photographs
Authors: Eisenacher C. , Lefebvre S. , Stamminger M.
Published: April 2008

The goal of texture synthesis is to generate an arbitrarily large high‐quality texture from a small input sample. Generally, it is assumed that the input image is given as a flat, square piece of texture, thus it has to be carefully prepared from a picture taken under ideal conditions. Instead we would like to extract the input texture from any surface from within an arbitrary photograph. This introduces several challenges: Only parts of the photograph are covered with the texture of interest, perspective and scene geometry introduce distortions, and the texture is non‐uniformly sampled during the capture process. This breaks many of the assumptions used for synthesis.

In this paper we combine a simple novel user interface with a generic per‐pixel synthesis algorithm to achieve high‐quality synthesis from a photograph. Our interface lets the user locally describe the geometry supporting the textures by combining rational Bézier patches. These are particularly well suited to describe curved surfaces under projection. Further, we extend per‐pixel synthesis to account for arbitrary texture sparsity and distortion, both in the input image and in the synthesis output. Applications range from synthesizing textures directly from photographs to high‐quality texture completion.
Real‐Time Translucent Rendering Using GPU‐based Texture Space Importance Sampling
Authors: Chang Chih‐Wen , Lin Wen‐Chieh , Ho Tan‐Chi , Huang Tsung‐Shian , Chuang Jung‐Hong
Published: April 2008

We present a novel approach for real‐time rendering of translucent surfaces. The computation of subsurface scattering is performed by first converting the integration over the 3D model surface into an integration over a 2D texture space and then applying importance sampling based on the irradiance stored in the texture. Such a conversion leads to a feasible GPU implementation and makes real‐time frame rate possible. Our implementation shows that plausible images can be rendered in real time for complex translucent models with dynamic light and material properties. For objects with more apparent local effect, our approach generally requires more samples that may downgrade the frame rate. To deal with this case, we decompose the integration into two parts, one for local effect and the other for global effect, which are evaluated by the combination of available methods [DS03, MKB* 03a] and our texture space importance sampling, respectively. Such a hybrid scheme is able to steadily render the translucent effect in real time with a fixed amount of samples.
Image‐based Aging Using Evolutionary Computing
Authors: Hubball Daniel , Chen Min , Grant Phil W.
Published: April 2008

Aging has considerable visual effects on the human face and is difficult to simulate using a universally‐applicable global model. In this paper, we focus on the hypothesis that the patterns of age progression (and regression) are related to the face concerned, as the latter implicitly captures the characteristics of gender, ethnic origin, and age group, as well as possibly the person‐specific development patterns of the individual. We use a data‐driven framework for automatic image‐based facial transformation in conjunction with a database of facial images. We build a novel parameterized model for encoding age‐transformation in addition with the traditional model for face description. We utilize evolutionary computing to learn the relationship between the two models. To support this work, we also developed a new image warping algorithm based on non‐uniform radial basis functions (NURBFs). Evolutionary computing was also used to handle the large parameter space associated with NURBFs. In comparison with several different methods, it consistently provides the best results against the ground truth.
Prediction Error Estimation Under Bregman Divergence for Non‐Parametric Regression and Classification
Authors: ZHANG CHUNMING
Published: April 2008

Abstract. Prediction error is critical to assess model fit and evaluate model prediction. We propose the cross‐validation (CV) and approximated CV methods for estimating prediction error under the Bregman divergence (BD), which embeds nearly all of the commonly used loss functions in the regression, classification procedures and machine learning literature. The approximated CV formulas are analytically derived, which facilitate fast estimation of prediction error under BD. We then study a data‐driven optimal bandwidth selector for local‐likelihood estimation that minimizes the overall prediction error or equivalently the covariance penalty. It is shown that the covariance penalty and CV methods converge to the same mean‐prediction‐error‐criterion. We also propose a lower‐bound scheme for computing the local logistic regression estimates and demonstrate that the algorithm monotonically enhances the target local likelihood and converges. The idea and methods are extended to the generalized varying‐coefficient models and additive models.
CONSIDERING THE SOURCE: DOES THE COUNTRY OF ORIGIN OF FDI MATTER TO ECONOMIC GROWTH?*
Authors: Ford Timothy C. , Rork Jonathan C. , Elmslie Bruce T.
Published: April 2008

ABSTRACT It has long been surmised that firms controlled by different countries may have unequal effects on the host economies in which they locate. By looking at the seven major source countries of foreign direct investment (FDI) in the United States, we provide empirical evidence that the state growth effects of FDI differ by source country. We attribute these differential growth effects to the relative differences in factor endowments between the source country and the state. The implication of this result is that technology transfer, believed to be the engine of economic growth, becomes more costly the more dissimilar the endowments.
EUROPEAN UNION REGIONAL PRODUCTIVITY DYNAMICS: A “DISTRIBUTIONAL” APPROACH*
Authors: Fotopoulos Georgios
Published: April 2008

ABSTRACTWorking within the “distributional approach,” this research offers evidence of past and future polarization in aggregate regional labor productivity in EU‐15. This finding is robust to alternative definitions of the spatial units used and does not appear to be the result of regional structural change. Spatial effects are found but are of rather localized nature. Turning to separate sectoral analyses suggests that past and future polarization in labor productivity across European regions may be associated with regional productivity differences in the services sectors.
NEXUS BETWEEN HOUSING AND THE MACRO ECONOMY: THE HONG KONG CASE
Authors: HO LOK SANG , WONG GARY
Published: April 2008

This paper shows that, consistent with the ‘economic base’ theory, exports drive domestic consumption and domestic investment, but housing appears to serve as an important link between exports and domestic expenditures. Focusing on the Hong Kong economy, which is a small open economy with a big population, we found that exports and interest rates drive housing prices over a long period, while housing prices in turn drive domestic expenditures.
Screening for LRRK2 mutations in patients with Parkinson’s disease in Russia: identification of a novel LRRK2 variant
Authors: Pchelina S. N. , Yakimovskii A. F. , Emelyanov A. K. , Ivanova O. N. , Schwarzman A. L. , Singleton A. B.
Published: April 2008

Background and purpose:  Mutations in LRRK2, encoding leucine‐rich repeat kinase 2 (or Dardarin), cause autosomal dominant Parkinson's disease (AdPD) and are also found in sporadic PD (sPD). To investigate the frequency of LRRK2 mutations in a sample of Russian PD patients.

Methods:  We sequenced the complete coding region of LRRK2 in 65 patients with AdPD and in 30 patients with sPD. Furthermore, in 20 patients with AdPD and in 159 patients with sPD we screened several common LRRK2 mutations (G2019S, R1441C/G/H, I2012T and I2020T).

Results:  Five AdPD patients had the LRRK2 G2019S mutation (5.9%, 5/85). In addition, we discovered a novel LRRK2 variant V1613A in a family with a tremor dominant form of AdPD; this variant was not present in controls. We identified two patients with LRRK2 mutations in sPD: one with the G2019S mutation (0.5; 1/189) and another with the previously described R1441C mutation (0,5; 1/189).

Conclusions:  LRRK2 mutations are common amongst patients with PD in Russia. The results also show that the G2019S mutation is the most frequent. We identified one novel mutation in a functional region of LRRK2.
THE ANALYSIS OF EUROPEAN COMPANY ACCOUNTS
Authors: Clay J. P.
Published: April 2008

Numerous details have been given here of the faults (in English eyes) to be found in European accounts, and of the progress that is being made towards overcoming them; but the greatest obstacle to progress is undoubtedly psychological—the failure of many in the financial world to realize that it is desirable for accounts to be accurate, comprehensive and clear. At Courchevel the European analysts discussed with interest the normal English auditors' report, whch attests that the accompanying accounts give ‘a true and fair view’; one remarked admiringly, ‘The English bring sport into everything: even a shareholder must have a fair chance, as though he were a fox’. This attitude, or somethmg like it, is becoming more widespread, but it is still far from universal; until it is more nearly so, it must be expected that progress will continue to be slow.
CUSTOMS UNIONS AND LATIN AMERICAN INTEGRATION
Authors: Griffin Keith , Ffrench‐Davis Ricardo
Published: April 2008

The potential gains from a customs union may be divided into two categories, those which improve the allocation of resources and those which lead to an increase in the quantity of available resources. The former are static, once‐for‐all gains, while the latter are cumulative gains. The static benefits can be represented as derived from changed price relationships along a fixed production frontier and as a movement to the frontier. The dynamic benefits of customs unions, on the other hand, lead to an increase in the rate of economic growth, and can be represented best by a series of shifts of the production frontier. The potential increase in welfare from improved resource allocation is likely to be small. The benefits from dynamic processes, as we try to demonstrate below, may be somewhat larger. Whether these potential benefits are translated into actual gains will depend upon whether the member countries are able to overcome certain problems of short‐run adjustment. There is no certainty they will be able to do this.
Antarctic terrestrial life – challenging the history of the frozen continent?
Authors: Convey Peter , Gibson John A. E. , Hillenbrand Claus‐Dieter , Hodgson Dominic A. , Pugh Philip J. A. , Smellie John L. , Stevens Mark I.
Published: April 2008

Antarctica is a continent locked in ice, with almost 99.7% of current terrain covered by permanent ice and snow, and clear evidence that, as recently as the Last Glacial Maximum (LGM), ice sheets were both thicker and much more extensive than they are now. Ice sheet modelling of both the LGM and estimated previous ice maxima across the continent give broad support to the concept that most if not all currently ice‐free ground would have been overridden during previous glaciations. This has given rise to a widely held perception that all Mesozoic (pre‐glacial) terrestrial life of Antarctica was wiped out by successive and deepening glacial events. The implicit conclusion of such destruction is that most, possibly all, contemporary terrestrial life has colonised the continent during subsequent periods of glacial retreat. However, several recently emerged and complementary strands of biological and geological research cannot be reconciled comfortably with the current reconstruction of Antarctic glacial history, and therefore provide a fundamental challenge to the existing paradigms. Here, we summarise and synthesise evidence across these lines of research. The emerging fundamental insights corroborate substantial elements of the contemporary Antarctic terrestrial biota being continuously isolated in situ on a multi‐million year, even pre‐Gondwana break‐up timescale. This new and complex terrestrial Antarctic biogeography parallels recent work suggesting greater regionalisation and evolutionary isolation than previously suspected in the circum‐Antarctic marine fauna. These findings both require the adoption of a new biological paradigm within Antarctica and challenge current understanding of Antarctic glacial history. This has major implications for our understanding of the key role of Antarctica in the Earth System.
Neurogenic development of the visual areas in the Chinese softshell turtle (Pelodiscus sinensis) and evolutionary implications
Authors: Xi Chao , Zeng ShaoJu , Zhang XinWen , Zuo MingXue
Published: April 2008

To characterize the neurogenic development of the visual areas of the turtle (Pelodiscus sinensis) during embryogenesis, a single dose of [3H]‐thymidine (10 µCi) was injected into egg yolks from stages S11~12 to S21. At hatching, localization of [3H]‐thymidine incorporation was examined, and led to three main observations. (1) Neurogenesis occurred in the stratum griseum centrale of the tectum opticum from S11~12 to S16 with a peak at S12. No obvious gradients of neurogenesis were observed. (2) Neurogenesis in the nucleus rotundus (Rot) and in the dorsal lateral geniculate nucleus (GLd) occurred from S11~12 to S15. Gradients of neurogenesis were detected along ventral–dorsal and lateral–medial axes in the Rot, but only the latter neurogenic gradient occurred in the GLd. (3) In the visual region of the dorsal ventricular ridge, neurogenesis lasted from S11~12 to S16. Similarly, neurogenesis occurred from S11~12 to S16~17 in the dorsal cortex, with a peak at S12 for both telencephalic visual regions. Neurogenesis followed a ventrolateral to dorsomedial gradient in the visual region of the dorsal ventricular ridge, and a superficial to deep gradient in the caudal dorsal cortex. A significant number of neurons in the rostral dorsal cortex followed a deep (earlier arising) to superficial (later arising) pattern of neurogenesis, similar to that in the avian Wulst or in the mammalian isocortex. Finally, we compared the timing and development of neurogenesis in the turtle with birds and mammals to understand the evolutionary implications of these processes.
The optic vesicle promotes cornea to lens transdifferentiation in larval Xenopus laevis
Authors: Cannata Stefano M. , Bernardini Sergio , Filoni Sergio , Gargioli Cesare
Published: April 2008

The outer cornea and pericorneal epidermis (lentogenic area) of larval Xenopus laevis are the only epidermal regions competent to regenerate a lens under the influence of the retinal inducer. However, the head epidermis of the lentogenic area can acquire the lens‐regenerating competence following transplantation of an eye beneath it. In this paper we demonstrate that both the outer cornea and the head epidermis covering a transplanted eye are capable of responding not only to the retinal inducer of the larval eye but also to the inductive action of the embryonic optic vesicle by synthesizing crystallins. As the optic vesicle is a very weak lens inductor, which promotes crystallin synthesis only on the lens biased ectoderm of the embryo, these results indicate that the lens‐forming competence in the outer cornea and epidermis of larval X. laevis corresponds to the persistence and acquisition of a condition similar to that of the embryonic biased ectoderm.