bluuebunny/crossref_metadata_2025 huggingface dataset:
The Roles of Chemokines in Rabies Virus Infection: Overexpression May Not Always Be Beneficial
Authors: Zhao Ling , Toriumi Harufusa , Kuang Yi , Chen Huanchun , Fu Zhen F.
Published: September 2009

It was found previously that induction of innate immunity, particularly chemokines, is an important mechanism of rabies virus (RABV) attenuation. To evaluate the effect of overexpression of chemokines on RABV infection, chemokines macrophage inflammatory protein 1α (MIP-1α), RANTES, and IP-10 were individually cloned into the genome of attenuated RABV strain HEP-Flury. These recombinant RABVs were characterized in vitro for growth properties and expression of chemokines. It was found that all the recombinant viruses grew as well as the parent virus, and each of the viruses expressed the intended chemokine in a dose-dependent manner. When these viruses were evaluated for pathogenicity in the mouse model, it was found that overexpression of MIP-1α further decreased RABV pathogenicity by inducing a transient innate immune response. In contrast, overexpression of RANTES or IP-10 increased RABV pathogenicity by causing neurological diseases, which is due to persistent and high-level expression of chemokines, excessive infiltration and accumulation of inflammatory cells in the central nervous system, and severe enhancement of blood-brain barrier permeability. These studies indicate that overexpression of chemokines, although important in controlling virus infection, may not always be beneficial to the host.
Tryptophan Residues in the Portal Protein of Herpes Simplex Virus 1 Critical to the Interaction with Scaffold Proteins and Incorporation of the Portal into Capsids
Authors: Yang Kui , Baines Joel D.
Published: September 2009

Incorporation of the herpes simplex virus 1 (HSV-1) portal vertex into the capsid requires interaction with a 12-amino-acid hydrophobic domain within capsid scaffold proteins. The goal of this work was to identify domains and residues in the U
L
6-encoded portal protein pU
L
6 critical to the interaction with scaffold proteins. We show that whereas the wild-type portal and scaffold proteins readily coimmunoprecipitated with one another in the absence of other viral proteins, truncation beyond the first 18 or last 36 amino acids of the portal protein precluded this coimmunoprecipitation. The coimmunoprecipitation was also precluded by mutation of conserved tryptophan (W) residues to alanine (A) at positions 27, 90, 127, 163, 241, 262, 532, and 596 of U
L
6. All of these W-to-A mutations precluded the rescue of a viral deletion mutant lacking U
L
6, except W163A, which supported replication poorly, and W596A, which fully rescued replication. A recombinant virus bearing the W596A mutation replicated and packaged DNA normally, and scaffold proteins readily coimmunoprecipitated with portal protein from lysates of infected cells. Thus, viral functions compensated for the W596A mutation's detrimental effects on the portal-scaffold interaction seen during transient expression of portal and scaffold proteins. In contrast, the W27A mutation precluded portal-scaffold interactions in infected cell lysates, reduced the solubility of pU
L
6, decreased incorporation of the portal into capsids, and abrogated viral-DNA cleavage and packaging.
Cleavage of IPS-1 in Cells Infected with Human Rhinovirus
Authors: Drahos Jennifer , Racaniello Vincent R.
Published: September 2009

Rhinoviruses are prevalent human pathogens that are associated with life-threatening acute asthma exacerbations. The innate immune response to rhinovirus infection, which may play an important role in virus-induced asthma induction, has not been comprehensively investigated. We examined the innate immune response in cells infected with human rhinovirus 1a (HRV1a). Beta interferon (IFN-β) mRNA was induced in HRV1a-infected cells at levels significantly lower than in cells infected with Sendai virus. To understand the basis for this observation, we determined whether components of the pathway leading to IFN-β induction were altered during infection. Dimerization of the transcription factor IRF-3, which is required for synthesis of IFN-β mRNA, is not observed in cells infected with HRV1a. Beginning at 7 h postinfection, IPS-1, a protein that is essential for cytosolic sensing of viral RNA, is degraded in HRV1a-infected cells. Induction of apoptosis by puromycin led to the cleavage of IPS-1, but treatment of HRV1a-infected cells with the pan-caspase inhibitor, zVAD, did not block cleavage of IPS-1. IPS-1 is cleaved in vitro by caspase-3 and by the picornaviral proteinases 2A
pro
and 3C
pro
. Expression of HRV1a and polioviral 2A
pro
and 3C
pro
led to degradation of IPS-1 in cells. These results suggest that IPS-1 is cleaved during HRV1a infection by three different proteases. Cleavage of IPS-1 may be a mechanism for evasion of the type I IFN response, leading to a more robust infection.
Role of RNA Structures in Genome Terminal Sequences of the Hepatitis C Virus for Replication and Assembly
Authors: Friebe Peter , Bartenschlager Ralf
Published: September 2009

Hepatitis C virus (HCV) is a positive-strand RNA virus replicating its genome via a negative-strand [(−)] intermediate. Little is known about replication signals residing in the 3′ end of HCV (−) RNA. Recent studies identified seven stem-loop structures (SL-I′, -IIz′, -IIy′, -IIIa′, -IIIb′, -IIIcdef′, and -IV′) in this region. In the present study, we mapped the minimal region required for RNA replication to SL-I′ and -IIz′, functionally confirmed the SL-IIz′ structure, and identified SL-IIIa′ to -IV′ as auxiliary replication elements. In addition, we show that the 5′ nontranslated region of the genome most likely does not contain
cis
-acting RNA structures required for RNA packaging into infectious virions.
Antagonism to and Intracellular Sequestration of Human Tetherin by the Human Immunodeficiency Virus Type 2 Envelope Glycoprotein
Authors: Le Tortorec Anna , Neil Stuart J. D.
Published: September 2009

Tetherin (CD317/BST-2), an interferon-induced membrane protein, restricts the release of nascent retroviral particles from infected cell surfaces. While human immunodeficiency virus type 1 (HIV-1) encodes the accessory genevputo overcome the action of tetherin, the lineage of primate lentiviruses that gave rise to HIV-2 does not. It has been previously reported that the HIV-2 envelope glycoprotein has a Vpu-like function in promoting virus release. Here we demonstrate that the HIV-2 Rod envelope glycoprotein (HIV-2 Rod Env) is a tetherin antagonist. Expression of HIV-2 Rod Env, but not that of HIV-1 or the closely related simian immunodeficiency virus (SIV) SIVmac1A11, counteracts tetherin-mediated restriction of Vpu-defective HIV-1 in a cell-type-specific manner. This correlates with the ability of the HIV-2 Rod Env to mediate cell surface downregulation of tetherin. Antagonism requires an endocytic motif conserved across HIV/SIV lineages in the gp41 cytoplasmic tail, but specificity for tetherin is governed by extracellular determinants in the mature Env protein. Coimmunoprecipitation studies suggest an interaction between HIV-2 Rod Env and tetherin, but unlike studies with Vpu, we found no evidence of tetherin degradation. In the presence of HIV-2 Rod Env, tetherin localization is restricted to thetrans-Golgi network, suggesting Env-mediated effects on tetherin trafficking sequester it from virus assembly sites on the plasma membrane. Finally, we recapitulated these observations in HIV-2-infected CD4+T-cell lines, demonstrating that tetherin antagonism and sequestration occur at physiological levels of Env expression during virus replication.
Occupational asthma and allergy in snow crab processing in Newfoundland and Labrador
Authors: Gautrin D , Cartier A , Howse D , Horth-Susin L , Jong M , Swanson M , Lehrer S , Fox G , Neis B
Published: September 2009

Background:

Risk factors and prevalence of occupational asthma (OA) and occupational allergy (OAl) in the snow crab-processing industry have been poorly studied.

Objective:

To estimate the prevalence of OA and OAl in snow crab-processing workers and determine their relationship with exposure to snow crab allergens and other potential risk factors.

Methods:

A total of 215 workers (120 female/95 male) were recruited from four plants in Newfoundland and Labrador, Canada in 2001–2002. Results from questionnaires, skin-prick tests to snow crab meat and cooking water, specific IgEs against the latter, spirometry and peak flow monitoring were used to develop a diagnostic algorithm. An index based on work history and exposure measurements of snow crab aeroallergens was developed to estimate the cumulative exposure for each worker.

Results:

The prevalences of almost certain or highly probable OA and OAl were 15.8% and 14.9%, respectively. A high cumulative exposure to crab allergens, in jobs mostly held by women, was associated with OA (odds ratio (OR) = 14.0, 95% CI 3.0 to 65.8) (highest vs lowest Cumulative Exposure Index) and with OAl (OR = 7.1, 95% CI 1.9 to 29.0); job held when symptoms started (cleaning, packing, freezing) also predicted OA (OR = 3.9, 95% CI 1.6 to 8.7) and OAl (OR = 3.2, 95% CI 1.4 to 7.5). Atopy (OR = 2.8, 95% CI 1.2 to 6.8), female gender (OR = 10.7, 95% CI 3.6 to 32.1) and smoking were significant determinants for OA (OR = 3.1, 95% CI 1.3 to 7.4).

Conclusions:

The prevalences of OA and OAl are high in snow crab-processing workers of Canada’s East Coast. Cumulative exposure to snow crab allergens was related to the prevalences of OA and OAl in a dose–response manner taking into account atopy, gender and smoking.
Cause-specific mortality of Dutch chlorophenoxy herbicide manufacturing workers
Authors: Boers D , Portengen L , Bueno-de-Mesquita H Bas , Heederik D , Vermeulen R
Published: September 2009

Objective:

A retrospective cohort study was conducted in two chlorophenoxy herbicide manufacturing factories, producing mainly 2,4,5-trichlorophenoxyacetic acid (factory A) and 4-chloro-2-methylphenoxyacetic acid, 4-chloro-2-methylphenoxy propanoic acid and 2,4-dichlorophenoxyacetic acid (factory B). Previously, we have shown elevated risks for mortality and cancer mortality in this cohort. The purpose of the current, third follow-up, is to provide an updated assessment of cause-specific mortality for both factories.

Methods:

The study population was defined as all persons working in one of the two factories during 1955–1985 for factory A, or during 1965–1986 for factory B. Analyses were performed using Cox proportional hazard models, using attained age as the timescale. Exposure to phenoxy herbicides and dioxins was expected to be different for factory A and factory B and the factories were therefore analysed separately.

Results:

Previously reported increased risks for respiratory cancer, non-Hodgkin’s lymphoma and ischaemic heart disease in factory A could not be confirmed in the present analysis. However, increased risks were observed for all cancers in both factory A (hazard ratio (HR) 1.31; 95% CI 0.86 to 2.01) and factory B (HR 1.54; 95% CI 1.00 to 2.37). Increased risks for urinary cancers (HR 4.2; 95% CI 0.99 to 17.89) and genital cancers (HR 2.93; 95% CI 0.61 to 14.15) were observed in factory A, consistent with earlier reported results in this population. More detailed analyses showed that this increased risk for urinary and genital cancers in exposed workers was not due to selection of healthy controls and could not be attributed to specific products or departments.

Conclusion:

The results of this study showed only slight increases in cancer mortality risk. The increased risk for urinary cancers is noteworthy, but could not be linked to a specific exposure and needs to be confirmed in similar cohorts.
Length Changes in Silver Hake (Merluccius bilinearis) Larvae: Effects of Formalin, Ethanol, and Freezing
Authors: Fowler G. M. , Smith S. J.
Published: September 2009

Silver hake (Merluccius bilinearis) larvae preserved in either formalin or ethanol decreased in length over time, most shrinkage being achieved in the first 15 d. The magnitude and variability of the length reduction was greater for smaller larvae. Rate and magnitude of shrinkage for ethanol-preserved larvae exceeded those of formalin-preserved larvae. Frozen specimens were extremely variable in length change response, and we noted a transition from shrinkage to expansion with increasing larval length.
Population Dynamics and Management of the Northwest Atlantic Harp Seal (Phoca groenlandica)
Authors: Roff Derek A. , Bowen W. Don
Published: September 2009

Previous methods of estimating population size and natural mortality rate in harp seals (Phoca groenlandica) are reviewed. Excepting the method of Beddington and Williams (Marine Mammal Comm., Washington, DC., Rep. MMC 79-03, 1980) all previous methods rely heavily upon the survival index method of estimating pup production. We describe the mathematical rationale underlying this method and indicate potential sources of bias. Beddington and Williams' analysis produces a combination of vital rates for 1952 that would not enable a population to persist in the absence of hunting. This suggests that the method may not be able to estimate these parameters accurately. This conclusion is supported by several unpublished analyses. We present an alternative method of analysis that is based on the concept of maximum likelihood. We estimate the rate of natural mortality and trend in 1 + population size from 1967 to 1980, using mark–recapture estimates of pup production in the late 1970s and the observed ratio of the survival of adjacent cohorts in the late 1960s and early 1970s to constrain population trajectories from a simulation model. From this analysis we conclude that the population is increasing and that the present total catch may be substantially smaller than the replacement yield.
Morphological Study of Sieve Efficiencies and Mandibular Surfaces in the Antarctic Krill, Euphausia superba
Authors: McClatchie Sam , Boyd Carl M.
Published: September 2009

The filtering basket of Euphausia superba is a complex comb filter with a wide range of mesh intervals. Intersetal distances range from approximately 15–95 μm between primary setae to 4–18 μm between secondary setae (setules). Microsetules with spacing of 1–2 μm thicken boundary layers surrounding secondary setae. Reynolds numbers for setules and microsetules, ranging from 0.006 to 0.95, limit the feeding modes available to E. superba for suspension feeding. Relative efficiency of particle capture, estimated from intersetule mesh size and grazing experiments with small phytoplankton (< 30 μm), show an asymptotic efficiency for particles 12–28 μm. Setule frequency distribution conservatively characterizes particle size selection for these small particles. The fine structure of the mandibular pars molaris varies between krill species and shows specialized surfaces that can split diatom chains, cut or fracture hard tests, and grind particles smaller than 10 μm.
Bioeconomic Production Function in Fisheries: Theoretical and Empirical Analysis
Authors: Hannesson Rögnvaldur
Published: September 2009

The traditional "fishing effort" approach to fisheries economics implies the existence of a production function with fishing effort and fish abundance as independent variables. It is shown how the existence of bionomic equilibrium depends on the shape of this production function, as well as the demand and effort cost functions. The analysis is related to the recent discussion of collapses in fisheries occurring as a result of fish availability being inversely related to fish abundance. A Cobb–Douglas production function, with effort and fish biomass as independent variables, is estimated for the Lofoten fishery. This indicates that the availability coefficient increases as the fish stock is depleted. Finally, the fishing effort approach is integrated with neoclassical production analysis. Fishing effort is regarded as being produced by labor and capital, and an effort frontier production function is estimated for selected Norwegian fisheries. This makes it possible to estimate optimal vessel size and capital intensity. Fishing vessels appear to be undersized but not too capital intensive.
Substrates of the Strait of Georgia, British Columbia
Authors: Luternauer J. L. , Clague J. J. , Pharo C. H.
Published: September 2009

The subtidal floor of the Strait of Georgia west of the Fraser River Delta and north to Texada Island is blanketed mainly by silt and clay derived from the Fraser River and from failed deposits at the delta front. On the western part of the Strait south of the delta to the San Juan and Orcas islands, sediments are mainly lag sand and gravel eroded from Pleistocene deposits by strong tidal currents. East of this area in a more sheltered embayed part of the Strait the seafloor is covered by silt and clay derived from local mainland streams and possibly from the Fraser River. North of southern Texada Island, influence of the Fraser River also has been minimal. Although bottoms of basins in this part of the Strait are blanketed by mud, coarser sediments are dominant elsewhere. Substrate materials in the northern Strait are products of wave and current reworking of Pleistocene deposits and deposition from local streams and rivers. The shoreline of the Strait is mainly rocky but includes sand and/or gravel beaches and deltaic tidal flats. Development of the intertidal zone has been controlled by Pleistocene glaciation, postglacial changes in sea level, local wave and current regimes, and sediment availability.
Review of the Benthos of the Strait of Georgia and Contiguous Fjords
Authors: Levings C. D. , Foreman R. E. , Tunnicliffe V. J.
Published: September 2009

The distribution of benthic communities in the Strait of Georgia is partially determined by the relative areas of various sediment types, their depths, and characteristics of overlying water. Rocky shores, which account for 88% of the shoreline length, have been fairly closely examined and communities have been described in the context of worldwide zonation patterns. The ecology of macrofauna and meiofauna of unconsolidated sediments at several estuaries (Nanaimo, Fraser, Squamish) has been documented. In eelgrass beds, very diverse invertebrate communities are found, whereas in brackish marshes closer to river mouths the ecosystem is characterized by a few very abundant species. To date, between 325 and 350 macroalgae species have been recorded from the shallow subtidal habitats of the Strait. In an intensive study at Bath Island, 10 algal communities were defined, each with an associated faunal group. The deep subtidal habitats are extensive: 71% of the surface area of the bottom of the Strait is between 50 and 300 m. These habitats are dominated by burrowing macrofauna such as holothurians, bivalves, and the heart urchin, Brisaster latifrons. The fauna of the rocky walls of fjords connecting with the Strait are characterized by cup corals, brachiopods, and sponges. Even though subject to low and fluctuating dissolved oxygen levels, a diverse fauna of epilithic organisms has been found in Saanich Inlet. Agglomeration, flocculation, and zooplankton pelletization are important mechanisms for transport of phytodetrital food for deep subtidal benthos. Provision of organic material from nearshore and riverine production sites is very important because of the extensive shoreline around the Strait. Juvenile salmonids, especially chinook (Oncorhynchus tshawytscha) and chum (O. keta), are strongly shoreline oriented and feed on epibenthic crustaceans and insects on foreshores. The deeper subtidal habitats in the Strait apparently do not support productive bottom fish communities. Although the major benthic assemblages have been described and standing crops have been estimated, there are very few data on the dynamics of benthic communities, secondary production of zoobenthos, benthic–pelagic coupling, or the quantitative relationships between oceanographic variables and benthic production.
Pollution in the Strait of Georgia: a Review
Authors: Waldichuk Michael
Published: September 2009

The Strait of Georgia, when considered as a whole, is still comparatively free of major pollution problems. Local environmental degradation has taken place, however, in waters on the periphery of the Strait, adjacent to urban communities and industries, such as pulp mills. The Fraser River, which is the major source of freshwater to the Strait, introduces natural and man-made materials that can adversely affect its estuary and the marine environment. The Strait of Georgia is flushed regularly, with deep waters being replaced about annually and waters in the upper layer having a considerably shorter residence time. Buildup of pollutants or their effects, e.g. oxygen depletion, are prevented in this way. However, there is refluxing of surface waters into the deep zone from the mixing region at the southern entrance to the Strait, and this means that surface pollutants such as oil could pollute the deep water and be retained there for up to a year. Problems affecting fisheries have been identified at the Fraser River Estuary arising from discharge of sewage treatment plant effluent. The major problem of pollution affecting fisheries in the Strait of Georgia has been bacteriological contamination from sewage, which has necessitated the closure of shellfish beds. The quality of oysters, as represented by condition factor and flavor, has deteriorated in the vicinity of some pulp mills. Evidence so far indicates that the "critical pollutants," e.g. petroleum hydrocarbons, organochlorines, and metals, which are persistent, toxic, and can be bioaccumulated by marine organisms, are present in low concentrations in the water, sediments, and biota away from the Fraser River Estuary. Wood wastes in the Strait of Georgia create a menace to navigation, especially during the spring freshet of the Fraser River.
GRAPH CLASSIFICATION BASED ON VECTOR SPACE EMBEDDING
Authors: RIESEN KASPAR , BUNKE HORST
Published: September 2009

Graphs provide us with a powerful and flexible representation formalism for pattern classification. Many classification algorithms have been proposed in the literature. However, the vast majority of these algorithms rely on vectorial data descriptions and cannot directly be applied to graphs. Recently, a growing interest in graph kernel methods can be observed. Graph kernels aim at bridging the gap between the high representational power and flexibility of graphs and the large amount of algorithms available for object representations in terms of feature vectors. In the present paper, we propose an approach transforming graphs into n-dimensional real vectors by means of prototype selection and graph edit distance computation. This approach allows one to build graph kernels in a straightforward way. It is not only applicable to graphs, but also to other kind of symbolic data in conjunction with any kind of dissimilarity measure. Thus it is characterized by a high degree of flexibility. With several experimental results, we prove the robustness and flexibility of our new method and show that our approach outperforms other graph classification methods on several graph data sets of diverse nature.
COMBINING EODH AND DIRECTIONAL GRADIENT DENSITY FOR OFFLINE SIGNATURE VERIFICATION
Authors: WEN JING , FANG BIN , TANG Y. Y. , WANG PATRICK S. P. , CHENG MIAO , ZHANG TAIPING
Published: September 2009

The main problem to identify skilled forgeries for offline signature verification lies in the fact that it is difficult to formalize distinguished feature representation of the signature patterns and design appropriate fusion scheme for various types of feature vectors. To tackle these problems, in this paper, we propose an approach to extract robust Edge Orientation Distance Histogram (EODH) descriptor which effectively reflects signature structure variations. In addition, directional gradient density features are employed for skilled forgery verification attempt. To exploit the full capacity of two sets of features, we designed the multilevel weighted fuzzy classifier and fuse match scores by way of selection priority. Experiments were conducted on a subcorpus of open MCYT signature database which is widely used for performance evaluation. It shows that the proposed method was able to improve verification accuracy.
COARSE-TO-FINE CLASSIFIER ENSEMBLE SELECTION USING CLUSTERING AND GENETIC ALGORITHMS
Authors: KIM YOUNG-WON , OH IL-SEOK
Published: September 2009

A good classifier ensemble should show high complementarity among classifiers to produce a high recognition rate and it should also have a small size to be efficient. This paper proposes a classifier ensemble selection algorithm operating in a coarse-to-fine paradigm. For the algorithm to be successful, the original classifier pool should be sufficiently diverse. So this paper produces a large classifier pool by combining several different classification algorithms and several feature subsets. The coarse selection stage reduces greatly the size of the classifier pool using a clustering algorithm. The fine selection finds the near-optimal ensemble using genetic algorithms. A hybrid genetic algorithm with improved searching capability is also proposed. The experimentation used handwritten numeral datasets and UCI datasets. The experimental results and the test of statistical significance showed that the proposed algorithm is superior to the conventional ones.
A FEATURE-BASED SCHEME FOR DETECTING AND CLASSIFYING VIDEO-SHOT TRANSITIONS BASED ON SPATIO-TEMPORAL ANALYSIS AND FUZZY CLASSIFICATION
Authors: LIN GUO-SHIANG , CHANG MIN-KUAN , CHIU SHIEN-TANG
Published: September 2009

In this paper, we propose a feature-based scheme for detecting different genres of video shot transitions based on spatio-temporal analysis and model parameter estimation. In feature extraction, the histogram difference and its modified versions are calculated from the effectiveness of detecting cuts and reducing the impact of fleeting lights. We propose a hybrid algorithm composed of adaptive thresholding, parameter calculation, and transition duration refinement to measure model parameters. Some properties of the associated model parameters of each transition are computed as features. A feature measuring the time gap between two consecutive shots is also adopted. After feature extraction, a fuzzy classifier integrates these features to distinguish nontransitions, cuts, and dissolve-type features from one to another.

Many test videos having different types of shots are used for performance evaluation. The experimental results demonstrate that the proposed scheme not only detects cuts, dissolves, and fades well, but also accurately locates the duration of each dissolve-type transition. In addition, the proposed scheme outperforms some existing methods in terms of cut and dissolve detection.
LIE GROUP FRAMEWORK OF ITERATIVE CLOSEST POINT ALGORITHM FOR n-D DATA REGISTRATION
Authors: YING SHIHUI , PENG JIGEN , DU SHAOYI , QIAO HONG
Published: September 2009

The iterative closet point (ICP) method is a dominant method for data registration that has attracted extensive attention. In this paper, a unified mathematical model of ICP based on Lie group representation is established. Under the framework, the registration problem is formulated into an optimization problem over a certain Lie group. In order to simplify the model and to reduce the dimension of parameter space, the translation part of geometric transformation is eliminated by calibrating the centers of two data sets under registration. As a result, a fast algorithm by solving an iterative linear system is designed for the optimization problem on Lie groups. Moreover, PCA and ICA methods are jointly applied to estimate the initial registration to achieve the global minimum. Finally, several illustrations and comparison experiments are presented to test the performance of the proposed algorithm.
HYPERSPHERICAL APPROACH TO STUDY THE SCHRÖDINGER EQUATION FOR AN N-PARTICLE SYSTEM
Authors: HASSANABADI H. , RAJABI A. A. , SHOJAEI M. M.
Published: September 2009

In the present work we give an exact analytical solution of the Schrödinger equation for an N-particle system by using the hyperspherical approach, in the presence of the hypercentral potential of form V(R) = a1R2+b1R-4+c1R-6 for both the ground state and the excited states.
DECAY OF 202Pb* FORMED IN 48Ca+154Sm REACTION USING THE DYNAMICAL CLUSTER-DECAY MODEL
Authors: KANWAR SHEFALI , SHARMA MANOJ K. , SINGH BIRBIKRAM , GUPTA RAJ K. , GREINER WALTER
Published: September 2009

The decay of compound nucleus 202 Pb *, formed in entrance channel reaction 48 Ca +154 Sm at different incident energies, is studied by using the dynamical cluster-decay model (DCM) where all decay products are calculated as emissions of preformed clusters through the interaction barriers. The calculated results show an excellent agreement with experimental data for the fusion-evaporation residue cross-section σ ER together with the fusion-fission cross-section σ FF (taken as a sum of the energetically favored symmetric [Formula: see text] and near symmetric A=65–75 plus complementary fragments), and the competing, non-compound-nucleus quasi-fission cross-section σ QF where the entrance channel is considered not to loose its identity (and hence with preformation factor P0=1). The interesting feature of this study is that the three decay processes (ER, FF and QF) are quite comparable at low energies, ER being the most dominant, whereas at higher energies FF becomes most probable followed by ER and QF. The prediction of two fission windows, the symmetric fission (SF) and the near symmetric fission (nSF) whose contribution is more at lower incident energies, suggests the presence of a fine structure effect in the fusion-fission of 202 Pb *. This result is attributed to the shell effects (magic shells) playing effective role in the fragment preformation yields for 48 Ca +154 Sm reaction at lower excitation energies, giving rise to "shoulders", to an otherwise Gaussian FF mass distribution, responsible for the QF process. As a further verification of this result, absence of "shoulders" (hence, the QF component) in the decay of 192 Pb * due to 48 Ca +144 Sm reaction is also shown to be given by the calculations, in agreement with experiments. The only parameter of the model is the neck-length ΔR which shows that the ER occurs first, having the largest values of ΔR, and the FF and QF processes occur almost simultaneously at lower incident energies but the FF takes over QF at higher incident energies. In other words, the three processes occur in different time scales, QF competing with FF at lower incident energies.
PYGMY DIPOLE RESONANCES
Authors: KREWALD S. , SPETH J.
Published: September 2009

Electric dipole strength below the particle emission threshold both in stable nuclei and short-lived isotopes has received increasing interest due to its astrophysical impact. In analogy to the giant dipole resonance, this strength is commonly referred to as pygmy resonance. Coulomb dissociation of neutron-rich unstable isotopes and nuclear resonance fluorescence photon scattering have begun to provide systematic data on electric dipole strength in various isotope chains. We review the present state of the art of theoretical approaches and point out some open problems. We emphasize the necessity of a simultaneous theoretical treatment of the nucleon separation energies and the energetically low-lying dipole strength because the presently available data do not exclude a non-collective nature of the pygmy strength.
A GROUP WITH THREE REAL IRREDUCIBLE CHARACTERS: ANSWERING A QUESTION OF MORETÓ AND NAVARRO
Authors: LEWIS MARK L.
Published: September 2009

In this paper, we construct a group with three real irreducible characters whose Sylow 2-subgroup is an iterated central extension of a Suzuki 2-group. This answers a question raised by Moretó and Navarro who asked whether such a group exists.
THE FIGURE EIGHT KNOT GROUP IS CONJUGACY SEPARABLE
Authors: CHAGAS S. C. , ZALESSKII P. A.
Published: September 2009

We prove that torsion free subgroups of GL2(ℂ) (abstractly) commensurable with the Euclidean Bianchi groups are conjugacy separable. As a consequence we deduce the result stated in the tittle.
ANALYSIS OF THE INTRA-MOLECULAR HYDROGEN BOND STRENGTH IN 3-HYDROXY-PROPENETHIAL (HPT)
Authors: FAZLI M. , JALBOUT A. F. , RAISSI H. , GHIASSI H. , YOOSEFIAN M.
Published: September 2009

The molecular structure and intra-molecular hydrogen bond energy of 20 conformers of 3-hydroxy-propenethial were investigated by using the MP2 and B3LYP levels of theory coupled to the 6-311++G** basis set. Also, computations for all the possible conformations of HPT in water and carbon tetrachloride solution were performed. The calculated geometrical parameters and conformational analyses in both gas phase and solution reveal that the closed ring hydrogen bonded structures are more stable than the remainder of the species. Hydrogen bond energies for various hydrogen-bonded conformers were obtained and investigated by means of the Bader theory of atoms in molecules (which is based on topological properties of the electron density).
SEMI-EMPIRICAL STUDY OF A SUPRAMOLECULE SWITCH
Authors: HUANG LIN CHUN , HU JUN JIE , LI BING RUI
Published: September 2009

Semi-empirical (PM6) electronic structure calculations are reported on a newly synthesized supramolecule. The supramolecule possesses two different states, with different location of the arm under the external stimulus. The computational results capture the two states, the key switch-like character of the supramolecule.
THEORETICAL COMPUTATIONAL STUDIES ON ELECTRONIC STRUCTURES, SPECTROSCOPIC PROPERTIES AND NITROGEN HETEROATOM EFFECT OF A SPECIES OF ASYMMETRICAL DIIMINE LIGAND PLATINUM(II) COMPLEXES
Authors: BAI FU-QUAN , LIU TAO , ZHOU XIN , ZHANG JIAN-PO , ZHANG HONG-XING
Published: September 2009

Electronic structures and spectroscopic properties of a series of platinum(II) complexes based on the C-linked asymmetrical diimine ligand (2-pyridyl-pyrazole (1), 2-pyridyl-1,2,4-triazole (2), 2-pyridyl-tetrazole (3), 2-pyrazine-pyrazole (4) have been studied by the time-dependent density functional theory calculations with polarizable continuum model. The ground- and excited-state structures were optimized by the density functional theory and single-excitation configuration interaction methods, respectively. The calculated structures and spectroscopic properties are in agreement with the corresponding experimental data. The results of the spectroscopic investigations revealed that the lowest-energy absorptions have1,3metal-to-ligand charge transfer (MLCT)/1,3single ligand centered charge transfer (ILCT) mixing characters. The highest-occupied molecular orbitals (HOMOs) of 1–4 are composed of Pt ( d yz) and azole, while the lowest-unoccupied molecular orbitals (LUMOs) are mainly localized upon the pyridyl-azolate ligand (70% on the pyridine segment). From 1 to 3, the molecular orbital (MO) energies of HOMO and LUMO are decreased and the HOMO energies are changed more remarkably. This is caused by that the conjugation of the azolate segment of the ligand are enhanced through introducing more N heteroatoms into this segment. As a result of MO energy change, the lowest-energy absorptions are blue-shifted in the order 1 < 2 < 3. With the replacement of pyridyl by pyrazine, the HOMO energy of 4 is comparable to 1, but the LUMO energy is decreased by 0.8 eV, and the lowest-energy absorptions are red-shifted to 2.36 eV. Otherwise, the phosphorescent emissions of these complexes have the 3MLCT/3ILCT characters, and should originate from the lowest-energy absorptions. The emissions of 1–4 are red-shifted in the order 3 < 2 < 1 < 4. The heteroatom effect is suitable for tuning the spectra of this kind of materials.
AB INITIO CALCULATIONS OF 14N NQR PARAMETERS AND 13C, 1H, AND 15N CHEMICAL SHIFTS INCLUDING A COMPARISON WITH EXPERIMENTAL NMR DATA FOR CYCLOTRISAZOBENZENE
Authors: ZAMAND NASSER , ALIAKBAR ALI R. , HADIPOUR NASSER L.
Published: September 2009

Nuclear quadrupole coupling constant, χ, and asymmetry parameter, η, of 14 N nucleus and 13 C , 1 H , and 15 N chemical shifts for cyclotrisazobenzene at the level of B3LYP and MP2 methods have been studied using the Gaussian 98 suite of programs. Also, nuclear quadrupole resonance (NQR) frequencies (ν0, ν+, ν-) for 14 N have been calculated, thoroughly. The optimized structure of the compound was very similar to that given by the X-ray crystallographic data. The electric field gradient (EFG) calculation verified that the N = N bonds are highly localized in this molecule; therefore, electron-pairs of the nitrogen atoms remain nonbonding. The comparison of the calculated chemical shifts with the experimental values for cyclotrisazobenzene shows no significant structural changes in solution.
CAN SEMIEMPIRICAL QUANTUM MODELS CALCULATE THE BINDING ENERGY OF HYDROGEN BONDING FOR BIOLOGICAL SYSTEMS?
Authors: FENG FENG , WANG HUAN , FANG WEI-HAI , YU JIAN-GUO
Published: September 2009

A modified semiempirical model named RM1BH, which is based on RM1 parameterizations, is proposed to simulate varied biological hydrogen-bonded systems. The RM1BH is formulated by adding Gaussian functions to the core–core repulsion items in original RM1 formula to reproduce the binding energies of hydrogen bonding of experimental and high-level computational results. In the parameterizations of our new model, 35 base-pair dimers, 18 amino acid residue dimers, 14 dimers between a base and an amino acid residue, and 20 other multimers were included. The results performed with RM1BH were compared with experimental values and the benchmark density-functional (B3LYP/6-31G**/BSSE) and Möller–Plesset perturbation (MP2/6-31G**/BSSE) calculations on various biological hydrogen-bonded systems. It was demonstrated that RM1BH model outperforms the PM3 and RM1 models in the calculations of the binding energies of biological hydrogen-bonded systems by very close agreement with the values of both high-level calculations and experiments. These results provide insight into the ideas, methods, and views of semiempirical modifications to investigate the weak interactions of biological systems.
THE INVESTIGATION ON ELECTRONIC PROPERTIES AND STABILITY OF POLYOXOMETALATES FUNCTIONALIZED BY ORGANOMETALLIC TITANIUM [CpTi · SiW9V3O40]4- BY DENSITY FUNCTIONAL THEORY
Authors: SI YANLING , CHEN WEILIN , ZHANG ZHIMING , WANG ENBO
Published: September 2009

The electronic structures of [ CpTi · SiW 9 V 3 O 40]4- constructed from Keggin–type polyoxometalates functionalized by CpTi 3+ group have been investigated by Density Functional Theory (DFT) methods. We discuss the relative stability affected by incorporating the CpTi 3+ group into the different sites of the [ SiW 9 V 3 O 40]7- framework on the basis of geometrical parameters, total bonding energies, fragment analysis and frontier molecular orbitals analysis. The calculated results indicated that the structure of the CpTi 3+ group coordinating to one terminal oxygen and two bridging oxygen atoms of the Keggin–type polyoxoanion (system a) is more stable than that to three bridging oxygen atoms (system b). In system a, Ti -Ob1, Ti -Ob2 and Ti - Ot1 are relatively shorter, and as result, it exhibits a more compact and nearly spherical structure of the well-known Keggin–type [ SiW 9 V 3 O 40]7-. Fragment analysis elucidates that there is deviation of ΔE B in systems a and b, which makes a significant contribution to the stability of system a. The stability of different isomeric forms of polyoxoanions appears to be a balance between the stabilizing ΔE O and ΔE E terms and the destabilizing ΔE P term. The relatively small energy differences (ΔE B = 4.26 eV ) between systems a and b arise directly from this balance. Frontier molecular orbitals analysis further confirms the stability order of systems a > b by the difference of the HOMO-LUMO energy gap.
A DFT STUDY OF MOLYBDATE-PHOSPHONIC ACID COMPLEX
Authors: AGHAIE M. , GHORBANI M. H. , FAZAELI R. , AGHAIE H.
Published: September 2009

The relative stability of Molybdate-Phosphonic Acid (MPA) Complex in gas phase has been carried out using Density Functional Theory (DFT) methods. The methods used for calculations are B3LYP, BP86 and B3PW91, with three series of basis sets: D95**, 6-31+G (d,p) and 6-31++G (d,p) for hydrogen and oxygen atoms; LANL2DZ for Mo and Phosphorus. Predicted geometry and relative stability are discussed. Equilibrium geometry in the ground electronic state energy has been calculated for 1:1 complex. The best result for energetic and geometrical ground state was obtained with Becke3LYP calculations. The Basis Set Superposition Error (BSSE) begins to converge for all methods/basis sets. For this complex, most levels of theory seem to give reasonable estimates of the known binding energies, but here, too, the BSSE overwhelms the reliability of the binding energies for these basis sets.
INTRINSIC FORMULATION OF GEOMETRIC INTEGRABILITY AND ASSOCIATED RICCATI SYSTEM GENERATING CONSERVATION LAWS
Authors: BRACKEN PAUL
Published: September 2009

An intrinsic version of the integrability theorem for the classical Bäcklund theorem is presented. It is characterized by a one-form which can be put in the form of a Riccati system. It is shown how this system can be linearized. Based on this result, a procedure for generating an infinite number of conservation laws is given.
CONSTRAINT ALGORITHM FOR k-PRESYMPLECTIC HAMILTONIAN SYSTEMS: APPLICATION TO SINGULAR FIELD THEORIES
Authors: GRÀCIA XAVIER , MARTÍN RUBÉN , ROMÁN-ROY NARCISO
Published: September 2009

The k-symplectic formulation of field theories is especially simple, since only tangent and cotangent bundles are needed in its description. Its defining elements show a close relationship with those in the symplectic formulation of mechanics. It will be shown that this relationship also stands in the presymplectic case. In a natural way, one can mimick the presymplectic constraint algorithm to obtain a constraint algorithm that can be applied to k-presymplectic field theory, and more particularly to the Lagrangian and Hamiltonian formulations of field theories defined by a singular Lagrangian, as well as to the unified Lagrangian–Hamiltonian formalism (Skinner–Rusk formalism) for k-presymplectic field theory. Two examples of application of the algorithm are also analyzed.
EFFECTS OF SPECTRAL DEPENDENCE IN PASS-THROUGH PHOTON-BASED BIOMEDICAL TRANSILLUMINATION
Authors: VACAS-JACQUES PAULINO , STROJNIK MARIJA , PAEZ GONZALO
Published: September 2009

We have proposed an interferometric setup for biomedical analysis in transillumination modality. Wavelength dependence of optical properties must be considered for selecting source and sample. An expansion of the sample optical properties, around the central wavelength of emission, serves to account for spectral effects. Expected spectral values depend on the central moments of the source, and specific constants associated to the optical properties of the sample. By matching wavelength characteristics of source and sample, a first-order approximation is applicable. In such case, the expected values are exactly the optical properties evaluated at the central wavelength. Furthermore, in the first-order approximation, the transillumination interferometer yields the integrated attenuation of the sample at the central wavelength of emission. We verify the latter assertion by performing a wavelength-dependent Monte Carlo analysis to calculate the response of the transillumination interferometer. Recovered attenuation coefficients, for imaging and characterization scenarios, are in agreement with the value computed at the central wavelength of the source.
TRANSCRANIAL NEAR-INFRARED SPECTROSCOPY OF SMOKING BRAINS
Authors: PUCCI OLIVIA , STEPANOV SANDER , TORONOV VLADISLAV
Published: September 2009

We used a mobile wireless near-infrared sensor for the noninvasive recording of cerebral hemoglobin concentration changes during cigarette smoking. Each measurement included 5 min of rest, 5 min of smoking imitation, and 5 min of actual smoking. We observed significant effects of the tobacco smoking on temporal changes in the human brain at time scales ranging from 200ms to about 1min. The most reproducible effects were an increase of the heartbeat rate and a decrease in the heartbeat power spectral density during smoking. Significant but highly individual changes due to smoking were observed in temporal patterns of hemodynamic fluctuations in 5–50s time scales. We have also found statistically significant slow increases in both oxy- and deoxy-hemoglobin concentrations during smoking.
PRELIMINARY STUDY ON SKIN CANCER DETECTION IN SENCAR MICE USING MUELLER OPTICAL COHERENCE TOMOGRAPHY
Authors: TODOROVIĆ MILOŠ , JIAO SHULIANG , STOICA GEORGE , WANG LIHONG V.
Published: September 2009

We report on the use of a fiber-based Mueller-matrix optical coherence tomography (OCT) system with continuous source-polarization modulation for in vivo imaging of early stages of skin cancer in SENCAR mice. A homemade hand-held probe with integrated optical scanning and beam delivering optics was coupled in the sample arm. The OCT images show the morphological changes in skin resulting from pre-cancerous papilloma formations that are consistent with histology, thus demonstrating the system's potential for early skin cancer detection.
IMPROVE OPTICAL CLEARING OF SKIN IN VITRO WITH PROPYLENE GLYCOL AS A PENETRATION ENHANCER
Authors: ZHI ZHONGWEI , HAN ZHENZHEN , LUO QINGMING , ZHU DAN
Published: September 2009

In order to enhance the optical clearing effect of topically applied optical clearing agents (OCAs), we evaluated the effect of propylene glycol (PG) as a chemical penetration enhancer (PE) on optical clearing of skin in vitro by observation and measurement of optical-transmittance and diffuse-reflectance spectra. Three OCAs, i.e., glycerol, D-sorbitol and PEG400, and two other penetration enhancers, Azone and Thiazone, were used in this study. The results indicated that the decrease of reduced scattering coefficient caused by OCA/PG was larger than that by pure OCA, and the change by OCA/water was the least after the same treatment time. There were significant differences for the reduced scattering coefficient at 630 nm after 120 min application of agents between OCA and OCA/PG. The efficacy of optical clearing caused by OCA/PG depended on the OCA itself. When PEG400 was mixed with three different PEs, we found the optical clearing were different. The penetration enhancing ability of PG was much better compared to Azone, and suboptimal to Thiazone. Also, this study provides evidence for the use of PG as a PE in order to improve skin optical clearing.
Five Questions for Pat Agre
Authors: Gualtieri Lisa
Published: September 2009

Patricia Agre has been director of Patient Education at Memorial Sloan-Kettering Cancer Center in New York City since 1994. She is a former registered nurse and respected photographer, who incorporated those skills into a career overseeing the creation and development of educations tools for cancer patients. She spoke with eLearn's editor-in-chief Lisa Gualtieri about her experiences producing comprehensive multimedia health care education tools.