bluuebunny/crossref_metadata_2025 huggingface dataset:
Calculation of out‐of‐field dose distribution in carbon‐ion radiotherapy by Monte Carlo simulation
Authors: Yonai Shunsuke , Matsufuji Naruhiro , Namba Masao
Published: July 2012

Purpose:

Recent radiotherapy technologies including carbon‐ion radiotherapy can improve the dose concentration in the target volume, thereby not only reducing side effects in organs at risk but also the secondary cancer risk within or near the irradiation field. However, secondary cancer risk in the low‐dose region is considered to be non‐negligible, especially for younger patients. To achieve a dose estimation of the whole body of each patient receiving carbon‐ion radiotherapy, which is essential for risk assessment and epidemiological studies, Monte Carlo simulation plays an important role because the treatment planning system can provide dose distribution only in/near the irradiation field and the measured data are limited. However, validation of Monte Carlo simulations is necessary. The primary purpose of this study was to establish a calculation method using the Monte Carlo code to estimate the dose and quality factor in the body and to validate the proposed method by comparison with experimental data. Furthermore, we show the distributions of dose equivalent in a phantom and identify the partial contribution of each radiation type.

Methods:

We proposed a calculation method based on a Monte Carlo simulation using the PHITS code to estimate absorbed dose, dose equivalent, and dose‐averaged quality factor by using theQ(L)‐L relationship based on the ICRP 60 recommendation. The values obtained by this method in modeling the passive beam line at the Heavy‐Ion Medical Accelerator in Chiba were compared with our previously measured data.

Results:

It was shown that our calculation model can estimate the measured value within a factor of 2, which included not only the uncertainty of this calculation method but also those regarding the assumptions of the geometrical modeling and the PHITS code. Also, we showed the differences in the doses and the partial contributions of each radiation type between passive and active carbon‐ion beams using this calculation method. These results indicated that it is essentially important to include the dose by secondary neutrons in the assessment of the secondary cancer risk of patients receiving carbon‐ion radiotherapy with active as well as passive beams.

Conclusions:

We established a calculation method with a Monte Carlo simulation to estimate the distribution of dose equivalent in the body as a first step toward routine risk assessment and an epidemiological study of carbon‐ion radiotherapy at NIRS. This method has the advantage of being verifiable by the measurement.
Identification of the Cdc48•20
S
Proteasome as an Ancient AAA+ Proteolytic Machine
Authors: Barthelme Dominik , Sauer Robert T.
Published: July 2012

Take Another Cap

Selective cytosolic protein degradation is mediated primarily by the proteasome, which is comprised of a core peptidase and a regulatory cap. Current dogma holds that the 20
S
core peptidase of the proteasome functions exclusively with the 19
S
regulatory particle in eukaryotes, with PAN in archaea, and with Mpa in mycobacteria.
Barthelme and Sauer
(p.
843
, published online 26 July 2012; see the Perspective by

Matouschek and Finley

) now suggest that another type of proteasome can assemble in archaea consisting of the double-ring AAA+ protein, Cdc48, in complex with the 20
S
core protease.
dSarm-ing Axon Degeneration
Authors: Milton Yu Xiaomeng , Luo Liqun
Published: July 2012

An axon self-destruction program may underlie neurodegeneration in injury and diseased states.
Utilizing Rapid Multiple-Locus Variable-Number Tandem-Repeat Analysis Typing To Aid Control of Hospital-Acquired Clostridium difficile Infection: a Multicenter Study
Authors: Hardy Katherine , Manzoor Susan , Marriott Claire , Parsons Helen , Waddington Claire , Gossain Savita , Szczepura Ala , Stallard Nigel , Hawkey Peter M.
Published: July 2012

The early identification of outbreaks is crucial for the control of
Clostridium difficile
infection. This study aimed to determine if the number of hospital-acquired
C. difficile
infections could be reduced by rapidly typing
C. difficile
strains using multiple-locus variable-number tandem-repeat analysis (MLVA) compared to typing using PCR ribotyping. A total of 16 hospitals were recruited to the study, and all periods of increased incidence (PIIs) of
C. difficile
infection were identified. The hospitals were randomized into two study arms, the test and the control, with all isolates typed in the test using MLVA and in the control using PCR ribotyping. Following a PII, each hospital received a structured questionnaire regarding control measures implemented or stopped prior to or following the typing results. During the study period, there were a total of 1,682 hospital-apportioned
C. difficile
toxin-positive cases, with 868 in the control and 814 in the test, with modeling demonstrating no differences between the two arms. A total of 245 PIIs occurred, involving 785 patients. There was a significant difference in the mean turnaround time between the ribotyping and MLVA typing (13.6 and 5.3 days, respectively [
P
< 0.001]). The discriminatory ability of MLVA was greater than ribotyping, with 85 outbreaks being confirmed by ribotyping and 62 by MLVA. In the test arm, 40.6% of respondents strongly agreed that the typing result had aided their management of clusters, as opposed to 9.9% in the control. The study demonstrated the utility of rapidly typing
C. difficile
strains, demonstrating that it aided the management of clusters, enabling effective targeting of infection control resources.
Subtractive Hybridization Yields a Silver Resistance Determinant Unique to Nosocomial Pathogens in the Enterobacter cloacae Complex
Authors: Kremer Anita N. , Hoffmann Harald
Published: July 2012

The heterogeneity and the increasing clinical importance of the
Enterobacter cloacae
complex have often been discussed. However, little is known about molecular factors causing pathogenicity within this nomenspecies. Here, we analyzed the genetic differences between an avirulent plant isolate and a pathogenic strain causing an outbreak with septicemia in three patients. We identified an IncHI-2 plasmid as a major difference between these two strains. Besides resistance to several antibiotics, this plasmid encoded a silver resistance determinant. We further showed that this
sil
determinant was present not only in the analyzed outbreak strain but also in the vast majority of clinical isolates of the
E. cloacae
complex, predominantly in (sub)species that frequently cause nosocomial infections. The identified
sil
determinant was highly conserved within the
E. cloacae
complex and mediated resistance to up to 600 μM silver nitrate. As silver is often used as a disinfectant and treatment for burn wounds, we present here an important fitness factor within the clinically most prevalent subspecies of the
E. cloacae
complex. This provides a possible explanation for their unequal involvement in nosocomial and especially burn wound infections.
Real-Time PCR for Diagnosing Helicobacter pylori Infection in Patients with Upper Gastrointestinal Bleeding: Comparison with Other Classical Diagnostic Methods
Authors: Saez Jesús , Belda Sofía , Santibáñez Miguel , Rodríguez Juan Carlos , Sola-Vera Javier , Galiana Antonio , Ruiz-García Montserrat , Brotons Alicia , López-Girona Elena , Girona Eva , Sillero Carlos , Royo Gloria
Published: July 2012

The aim of this study was to determine the diagnostic usefulness of quantification of the
H. pylori
genome in detection of infection in patients with upper gastrointestinal bleeding (UGB). A total of 158 consecutive patients with digestive disorders, 80 of whom had clinical presentation of UGB, were studied. The number of microorganisms was quantified using a real-time PCR system which amplifies the urease gene with an internal control for eliminating the false negatives. A biopsy sample from the antrum and corpus of each patient was processed. The rapid urease test, culture, histological study, stool antigen test, and breath test were done. The gold standard was a positive culture or positive results in at least two of the other techniques. When a positive result was defined as any number of microorganisms/human cell, the sensitivity of real-time PCR was greater in bleeding patients, especially in the gastric corpus: 68.4% (95% confidence interval [CI], 52.3 to 84.5%) in non-UGB patients versus 91.5% (95% CI, 79.6 to 97.6%) in UGB patients. When a positive result was defined as a number of microorganisms/human cell above the optimal value that maximizes the Youden index (>3.56 microorganisms/human cell in the antrum and >2.69 in the corpus), the sensitivity and specificity in UGB patients were over 80% in both antrum and corpus. Our findings suggest that some bleeding patients with infection caused by
H. pylori
may not be correctly diagnosed by classical methods, and such patients could benefit from the improved diagnosis provided by real-time PCR. However, the clinical significance of a small number of microorganisms in patients with negative results in classical tests should be evaluated.
HIV Controllers Maintain a Population of Highly Efficient Th1 Effector Cells in Contrast to Patients Treated in the Long Term
Authors: Vingert Benoît , Benati Daniela , Lambotte Olivier , de Truchis Pierre , Slama Laurence , Jeannin Patricia , Galperin Moran , Perez-Patrigeon Santiago , Boufassa Faroudy , Kwok William W. , Lemaître Fabrice , Delfraissy Jean-François , Thèze Jacques , Chakrabarti Lisa A.
Published: July 2012

HIV controllers are rare individuals who spontaneously control HIV replication in the absence of antiretroviral therapy. To identify parameters of the CD4 response that may contribute to viral control rather than merely reflect a persistently low viremia, we compared the T helper profiles in two groups of patients with more than 10 years of viral suppression: HIV controllers from the Agence Nationale de Recherche sur le SIDA et les Hépatites Virales (ANRS) CO18 cohort (
n
= 26) and efficiently treated patients (
n
= 16). Cells specific for immunodominant Gag and cytomegalovirus (CMV) peptides were evaluated for the production of 10 cytokines and cytotoxicity markers and were also directly quantified
ex vivo
by major histocompatibility complex (MHC) class II tetramer staining. HIV controller CD4
+
T cells were characterized by a higher frequency of gamma interferon (IFN-γ) production, perforin
+
/CD107a
+
expression, and polyfunctionality in response to Gag peptides. While interleukin 4 (IL-4), IL-17, and IL-21 production did not differ between groups, the cells of treated patients produced more IL-10 in response to Gag and CMV peptides, pointing to persistent negative immunoregulation after long-term antiretroviral therapy. Gag293 tetramer-positive cells were detected at a high frequency (0.12%) and correlated positively with IFN-γ-producing CD4
+
T cells in the controller group (
R
= 0.73;
P
= 0.003). Tetramer-positive cells were fewer in the highly active antiretroviral therapy (HAART) group (0.04%) and did not correlate with IFN-γ production, supporting the notion of a persistent immune dysfunction in HIV-specific CD4
+
T cells of treated patients. In conclusion, HIV controllers maintained a population of highly efficient Th1 effectors directed against Gag in spite of a persistently low antigenemia, while patients treated in the long term showed a loss of CD4 effector functions.
Epstein-Barr Virus Latent Membrane Protein-2A Induces ITAM/Syk- and Akt-Dependent Epithelial Migration through αV-Integrin Membrane Translocation
Authors: Fotheringham Julie A. , Coalson Nicole E. , Raab-Traub Nancy
Published: July 2012

Epstein-Barr virus (EBV) is a highly prevalent herpesvirus associated with epithelial cancers, including nasopharyngeal carcinoma (NPC). The EBV protein latent membrane protein 2 (LMP2) is expressed in NPC tumor tissue and has been shown to induce transformation, inhibit differentiation, and promote migration of epithelial cells. In this study, the effect of LMP2A on migration of human epithelial cells was further analyzed. LMP2A expression induced migration in human foreskin keratinocytes (HFK) and HaCaT keratinocytes measured by wound healing scratch assay and chemoattractant-induced Transwell migration assay. The induction of migration by LMP2A required the ITAM signaling domain of LMP2A and activation of the Syk tyrosine kinase. LMP2A-induced Transwell migration required the Akt signaling pathway, and activation of Akt by LMP2A required the ITAM signaling domain of LMP2A. LMP2A also induced phosphorylation of the Akt target GSK3β, a Wnt signaling mediator that has been shown to regulate the activity of focal adhesion kinase (FAK), a tyrosine kinase activated by clustering and ligand interaction of integrins. Inhibition of either FAK or its signaling mediator Src kinase inhibited LMP2A-induced migration. Interestingly, αV-integrin was greatly increased in membrane-enriched fractions by LMP2A, and a neutralizing antibody to αV-integrin blocked migration, suggesting that the effects of LMP2A on membrane-localized αV-integrin promoted migration. The results of this study indicate that LMP2A expression in human epithelial cells induces αV-integrin-dependent migration through a mechanism requiring ITAM-mediated Syk and Akt activation and inducing membrane translocation or stabilization of αV-integrin and FAK activation. The specific effects of LMP2A on an integrin with a diverse repertoire of ligand specificities could promote migration of different cell types and be initiated by multiple chemoattractants.
Human Parvovirus B19 DNA Replication Induces a DNA Damage Response That Is Dispensable for Cell Cycle Arrest at Phase G
2
/M
Authors: Lou Sai , Luo Yong , Cheng Fang , Huang Qinfeng , Shen Weiran , Kleiboeker Steve , Tisdale John F. , Liu Zhengwen , Qiu Jianming
Published: July 2012

Human parvovirus B19 (B19V) infection is highly restricted to human erythroid progenitor cells, in which it induces a DNA damage response (DDR). The DDR signaling is mainly mediated by the ATR (ataxia telangiectasia-mutated and Rad3-related) pathway, which promotes replication of the viral genome; however, the exact mechanisms employed by B19V to take advantage of the DDR for virus replication remain unclear. In this study, we focused on the initiators of the DDR and the role of the DDR in cell cycle arrest during B19V infection. We examined the role of individual viral proteins, which were delivered by lentiviruses, in triggering a DDR in
ex vivo
-expanded primary human erythroid progenitor cells and the role of DNA replication of the B19V double-stranded DNA (dsDNA) genome in a human megakaryoblastoid cell line, UT7/Epo-S1 (S1). All the cells were cultured under hypoxic conditions. The results showed that none of the viral proteins induced phosphorylation of H2AX or replication protein A32 (RPA32), both hallmarks of a DDR. However, replication of the B19V dsDNA genome was capable of inducing the DDR. Moreover, the DDR
per se
did not arrest the cell cycle at the G
2
/M phase in cells with replicating B19V dsDNA genomes. Instead, the B19V nonstructural 1 (NS1) protein was the key factor in disrupting the cell cycle via a putative transactivation domain operating through a p53-independent pathway. Taken together, the results suggest that the replication of the B19V genome is largely responsible for triggering a DDR, which does not perturb cell cycle progression at G
2
/M significantly, during B19V infection.
The Attenuated Genotype of Varicella-Zoster Virus Includes an ORF0 Transitional Stop Codon Mutation
Authors: Peters Geoffrey A. , Tyler Shaun D. , Carpenter John E. , Jackson Wallen , Mori Yasuko , Arvin Ann M. , Grose Charles
Published: July 2012

Varicella-zoster virus (VZV) is the first of the human herpesviruses to be attenuated and subsequently approved as a live vaccine to prevent varicella and herpes zoster. Both the attenuated VZV vaccine, called vaccine Oka or vOka, and the parental strain pOka have been completely sequenced. Yet the specific determinants of attenuation are uncertain. The open reading frame (ORF) with the most single nucleotide polymorphisms (SNPs), ORF62, encodes the regulatory protein IE62, but IE62 studies have failed to define a specific SNP associated with attenuation. We have completed next-generation sequencing of the VZV Ellen genome, a strain known to be highly attenuated by its very limited replication in human skin xenografts in the SCID mouse model of VZV pathogenesis. A comparative analysis of the Ellen sequence with all other complete VZV sequences was extremely informative. In particular, an unexpected finding was a stop codon mutation in Ellen ORF0 (herpes simplex virus UL56 homolog) identical to one found in vOka, combined with the absence of polymorphisms in most Ellen ORFs that were known to be mutated in vOka. The mutated ORF0 protein was also imaged in both two dimensions and three dimensions by confocal microscopy. The probability of two VZV strains not connected by a recent common ancestor having an identical ORF0 SNP by chance would be 1 × 10
−8
, in other words, extremely unlikely. Taken together, these bioinformatics analyses strongly suggest that the stop codon ORF0 SNP is one of the determinants of the attenuation genotype of live VZV vaccines.
Reverse Genetics Recovery of Lujo Virus and Role of Virus RNA Secondary Structures in Efficient Virus Growth
Authors: Bergeron Éric , Chakrabarti Ayan K. , Bird Brian H. , Dodd Kim A. , McMullan Laura K. , Spiropoulou Christina F. , Nichol Stuart T. , Albariño César G.
Published: July 2012

Arenaviruses are rodent-borne viruses with a bisegmented RNA genome. A genetically unique arenavirus, Lujo virus, was recently discovered as the causal agent of a nosocomial outbreak of acute febrile illness with hemorrhagic manifestations in Zambia and South Africa. The outbreak had a case fatality rate of 80%. A reverse genetics system to rescue infectious Lujo virus from cDNA was established to investigate the biological properties of this virus. Sequencing the genomic termini showed unique nucleotides at the 3′ terminus of the S segment promoter element. While developing this system, we discovered that reconstructing infectious Lujo virus using the previously reported L segment intergenic region (IGR), comprising the arenaviral transcription termination signal, yielded an attenuated Lujo virus. Resequencing revealed that the correct L segment IGR was 36 nucleotides longer, and incorporating it into the reconstructed Lujo virus restored the growth rate to that of the authentic clinical virus isolate. These additional nucleotides were predicted to more than double the free energy of the IGR main stem-loop structure. In addition, incorporating the newly determined L-IGR into a replicon reporter system enhanced the expression of a luciferase reporter L segment. Overall, these results imply that an extremely stable secondary structure within the L-IGR is critical for Lujo virus propagation and viral protein production. The technology for producing recombinant Lujo virus now provides a method to precisely investigate the molecular determinants of virulence of this newly identified pathogen.
Entry of Influenza A Virus with a α2,6-Linked Sialic Acid Binding Preference Requires Host Fibronectin
Authors: Leung Horasis S. Y. , Li Olive T. W. , Chan Renee W. Y. , Chan Michael C. W. , Nicholls John M. , Poon Leo L. M.
Published: July 2012

The receptor binding specificity of influenza A virus is one of the major determinants of viral tropism and host specificity. In general, avian viral hemagglutinin prefers to bind to α2,3-linked sialic acid, whereas the human viral hemagglutinin prefers to bind to α2,6-linked sialic acid. Here, we demonstrate that host fibronectin protein plays an important role in the life cycle of some influenza A viruses. Treating cells with anti-fibronectin antibodies or fibronectin-specific small interfering RNA can inhibit the virus replication of human H1N1 influenza A viruses. Strikingly, these inhibitory effects cannot be observed in cells infected with H5N1 viruses. By using reverse genetics techniques, we observed that the receptor binding specificity, but not the origin of the hemagglutinin subtype, is responsible for this differential inhibitory effect. Changing the binding preference of hemagglutinin from α2,6-linked sialic acid to α2,3-linked sialic acid can make the virus resistant to the anti-fibronectin antibody treatment and vice versa. Our further characterizations indicate that anti-fibronectin antibody acts on the early phase of viral replication cycle, but it has no effect on the initial binding of influenza A virus to cell surface. Our subsequent investigations further show that anti-fibronectin antibody can block the postattachment entry of influenza virus. Overall, these results indicate that the sialic acid binding preference of influenza viral hemagglutinin can modulate the preferences of viral entry pathways, suggesting that there are subtle differences between the virus entries of human and avian influenza viruses.
Nonstructural Nipah Virus C Protein Regulates both the Early Host Proinflammatory Response and Viral Virulence
Authors: Mathieu Cyrille , Guillaume Vanessa , Volchkova Valentina A. , Pohl Christine , Jacquot Frederique , Looi Ren Yih , Wong Kum Thong , Legras-Lachuer Catherine , Volchkov Viktor E. , Lachuer Joel , Horvat Branka
Published: July 2012

Nipah virus (NiV) is a highly pathogenic, negative-strand RNA paramyxovirus that has recently emerged from flying foxes to cause serious human disease. We have analyzed the role of the nonstructural NiV C protein in viral immunopathogenesis using recombinant virus lacking the expression of NiV C (NiVΔC). While wild-type NiV was highly pathogenic in the hamster animal model, NiVΔC was strongly attenuated. Replication of NiVΔC was followed by the production of NiV-specific antibodies and associated with higher recruitment of inflammatory cells and less intensive histopathological lesions in different organs than in wild-type-NiV-infected animals. To analyze the molecular basis of NiVΔC attenuation, we studied early changes in gene expression in infected primary human endothelial cells, a major cellular target of NiV infection. The transcriptomic approach revealed the striking difference between wild-type and mutant NiV in the expression of genes involved in immunity, with the particularly interesting differential patterns of proinflammatory cytokines. Compared to wild-type virus, NiVΔC induced increased expression of interleukin 1 beta (IL-1β), IL-8, CXCL2, CXCL3, CXCL6, CCL20, and beta interferon. Furthermore, the expression of NiV C in stably transfected cells decreased the production of the same panel of cytokines, revealing a role of the C protein in the regulation of cytokine balance. Together, these results suggest that NiV C regulates expression of proinflammatory cytokines, therefore providing a signal responsible for the coordination of leukocyte recruitment and the chemokine-induced immune response and controlling the lethal outcome of the infection.
Increased Genetic and Phenotypic Stability of a Promising Live-Attenuated Respiratory Syncytial Virus Vaccine Candidate by Reverse Genetics
Authors: Luongo Cindy , Winter Christine C. , Collins Peter L. , Buchholz Ursula J.
Published: July 2012

Human respiratory syncytial virus (RSV) is the most important viral cause of serious pediatric respiratory illness worldwide. Currently, the most promising live-attenuated vaccine candidate is a temperature-sensitive (
ts
) cDNA-derived virus named rA2
cp248/404/1030
ΔSH, in reference to its set of attenuating mutations. In a previous clinical study, more than one-third of postvaccination nasal wash isolates exhibited partial loss of the
ts
phenotype. Most of this instability appeared to be due to reversion at a missense point mutation called
1030
. This
1030
mutation is a single-nucleotide tyrosine-to-asparagine substitution at position 1321 (Y1321N) of the polymerase L protein that contributes to the
ts
and attenuation phenotypes of the vaccine candidate. The goals of the present study were to identify a reversion-resistant codon at position 1321 conferring a comparable level of attenuation and to use this to develop a genetically stable version of the vaccine virus. We modified wild-type (wt) RSV to insert each of the 20 possible amino acids at position 1321; 19 viruses were recoverable. We also investigated small deletions at or near this position, but these viruses were not recoverable. Phenotypic analysis identified alternative attenuating amino acids for position 1321. Several of these amino acids were predicted, based on the genetic code, to be refractory to deattenuation. Classical genetics, using temperature stress tests
in vitro
combined with nucleotide sequencing, confirmed this stability but identified a second site with a compensatory mutation at position 1313. It was possible to stabilize the 1313 site as well, providing a stable
1030
mutation. Further stress tests identified additional incidental mutations, but these did not reverse the
ts
/attenuation phenotype. An improved version of the vaccine candidate virus was constructed and validated
in vitro
by temperature stress tests and
in vivo
by evaluation of attenuation in seronegative chimpanzees. In addition to developing an improved version of this promising live-attenuated RSV vaccine candidate, this study demonstrated the propensity of an RNA virus to escape from attenuation but also showed that, through systematic analysis, genetics can be used to cut off the routes of escape.
Chikungunya Virus nsP3 Blocks Stress Granule Assembly by Recruitment of G3BP into Cytoplasmic Foci
Authors: Fros Jelke J. , Domeradzka Natalia E. , Baggen Jim , Geertsema Corinne , Flipse Jacky , Vlak Just M. , Pijlman Gorben P.
Published: July 2012

Chikungunya virus nonstructural protein nsP3 has an essential but unknown role in alphavirus replication and interacts with Ras-GAP SH3 domain-binding protein (G3BP). Here we describe the first known function of nsP3, to inhibit stress granule assembly by recruiting G3BP into cytoplasmic foci. A conserved SH3 domain-binding motif in nsP3 is essential for both nsP3-G3BP interactions and viral RNA replication. This study reveals a novel role for nsP3 as a regulator of the cellular stress response.
ON THE STRUCTURE OF GRADED LIE SUPERALGEBRAS
Authors: CALDERÓN MARTÍN ANTONIO J. , SÁNCHEZ DELGADO JOSÉ M.
Published: July 2012

We study the structure of graded Lie superalgebras with arbitrary dimension and over an arbitrary field 𝕂. We show that any of such algebras 𝔏 with a symmetric G-support is of the form 𝔏 = U + ∑jIj with U a subspace of 𝔏1 and any Ij a well-described graded ideal of 𝔏, satisfying [Ij, Ik] = 0 if j≠k. Under certain conditions, it is shown that 𝔏 = (⨁k∈K Ik) ⊕ (⨁q ∈Q Iq), where any Ik is a gr-simple graded ideal of 𝔏 and any Iq is a completely determined low-dimensional non-gr-simple graded ideal of 𝔏, satisfying [Iq, Iq'] = 0 for any q'∈Q with q ≠q'.
MASSLESS TWO-LOOP SELF-ENERGY DIAGRAM: HISTORICAL REVIEW
Authors: GROZIN A. G.
Published: July 2012

This class of diagrams has numerous applications. Many interesting results have been obtained for it.
CHARACTER EXPANSION FOR HOMFLY POLYNOMIALS III: ALL 3-STRAND BRAIDS IN THE FIRST SYMMETRIC REPRESENTATION
Authors: ITOYAMA H. , MIRONOV A. , MOROZOV A. , MOROZOV AND.
Published: July 2012

We continue the program of systematic study of extended HOMFLY polynomials, suggested in [A. Mironov, A. Morozov and And. Morozov, arXiv:1112.5754] and [A. Mironov, A. Morozov and And. Morozov, J. High Energy Phys. 03, 034 (2012), arXiv:1112.2654]. Extended polynomials depend on infinitely many time-variables, are close relatives of integrable τ-functions, and depend on the choice of the braid representation of the knot. They possess natural character decompositions, with coefficients which can be defined by exhaustively general formula for any particular number m of strands in the braid and any particular representation R of the Lie algebra GL(∞). Being restricted to "the topological locus" in the space of time-variables, the extended HOMFLY polynomials reproduce the ordinary knot invariants. We derive such a general formula, for m = 3, when the braid is parametrized by a sequence of integers (a1, b1, a2, b2, …) and for the first nonfundamental representation R = [2]. Instead of calculating the mixing matrices directly, as suggested [A. Mironov, A. Morozov and And. Morozov, J. High Energy Phys. 03, 034 (2012), arXiv:1112.2654], we deduce them from comparison with the known answers for torus and composite knots. A simple reflection symmetry converts the answer for the symmetric representation [2] into that for the antisymmetric one [1, 1]. The result applies, in particular, to the figure eight knot 41, and was further extended to superpolynomials in arbitrary symmetric and antisymmetric representations in H. Itoyama, A. Mironov, A. Morozov and And. Morozov, arXiv:1203.5978.
${\mathcal N}$-FOLD SUPERSYMMETRIC QUANTUM MECHANICS WITH REFLECTIONS
Authors: TANAKA TOSHIAKI
Published: July 2012

We formulate [Formula: see text]-fold supersymmetry in quantum mechanical systems with reflection operators. As in the cases of other systems, they possess the two significant characters of [Formula: see text]-fold supersymmetry, namely, almost isospectrality and weak quasi-solvability. We construct explicitly the most general one- and two-fold supersymmetric quantum mechanical systems with reflections. In the case of [Formula: see text], we find that there are seven inequivalent such systems, three of which are characterized by three arbitrary functions having definite parity while the other four characterized by two arbitrary functions. In addition, four of the seven inequivalent systems do not reduce to ordinary quantum systems without reflections. Furthermore, in certain particular cases, they are essentially equivalent to the most general two-by-two Hermitian matrix two-fold supersymmetric quantum systems obtained previously by us.
LUTTINGER LIQUID, SINGULAR INTERACTION AND QUANTUM CRITICALITY IN CUPRATE MATERIALS
Authors: DI CASTRO C. , CAPRARA S.
Published: July 2012

With particular reference to the role of the renormalization group (RG) approach and Ward identities (WI's), we start by recalling some old features of the one-dimensional Luttinger liquid as the prototype of non-Fermi-liquid behavior. Its dimensional crossover to the Landau normal Fermi liquid implies that a non-Fermi liquid, as, e.g., the normal phase of the cuprate high temperature superconductors, can be maintained in d>1 only in the presence of a sufficiently singular effective interaction among the charge carriers. This is the case when, nearby an instability, the interaction is mediated by critical fluctuations. We are then led to introduce the specific case of superconductivity in cuprates as an example of avoided quantum criticality. We will disentangle the fluctuations which act as mediators of singular electron–electron interaction, enlightening the possible order competing with superconductivity and a mechanism for the non-Fermi-liquid behavior of the metallic phase.

This paper is not meant to be a comprehensive review. Many important contributions will not be considered. We will also avoid using extensive technicalities and making full calculations for which we refer to the original papers and to the many good available reviews. We will here only follow one line of reasoning which guided our research activity in this field.
FERMIONS IN TWO DIMENSIONS, BOSONIZATION, AND EXACTLY SOLVABLE MODELS
Authors: DE WOUL JONAS , LANGMANN EDWIN
Published: July 2012

We discuss interacting fermion models in two dimensions, and, in particular, such that can be solved exactly by bosonization. One solvable model of this kind was proposed by Mattis as an effective description of fermions on a square lattice. We review recent work on a specific relation between a variant of Mattis' model and such a lattice fermion system, as well as the exact solution of this model. The background for this work includes well-established results for one-dimensional systems and the high-Tc problem. We also mention exactly solvable extensions of Mattis' model.
THE FULDE–FERRELL–LARKIN–OVCHINNIKOV STATE IN A 3D FERMI GAS SUBJECTED TO A 1D PERIODIC POTENTIAL
Authors: DEVREESE JEROEN P. A. , KLIMIN SERGHEI , WOUTERS MICHIEL , TEMPERE JACQUES
Published: July 2012

The question whether an imbalanced Fermi gas can accommodate polarized superfluidity has been the subject of intense study. One prominent candidate for a polarized superfluid state is the Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) state. In a one-dimensional (1D) Fermi gas, indirect evidence for this state has recently been found, but in the three-dimensional (3D) case, this exotic state has hitherto remained elusive. In this brief review, we study the influence of a 1D periodic potential on the FFLO state in an imbalanced 3D Fermi gas. We present a path-integral derivation of the free energy of the system, where the possibility of the FFLO state is included through the saddle-point approximation. Using the free energy, the phase diagram of the system, both at fixed chemical potentials and at fixed densities, is constructed, showing that the stability region of the FFLO state is significantly enlarged by the 1D potential. Subsequently, the influence of the potential on the FFLO pairing mechanism is investigated, leading to a qualitative understanding of the shape of the FFLO region in the different phase diagrams. We conclude by investigating the possibility of an FFLO state with a wave vector that lies skewed with respect to the direction along which the periodic potential varies. Our results provide an additional way to facilitate the experimental observation of the FFLO state in a 3D Fermi gas.
AC FLUCTUATION CONDUCTIVITY IN TYPE-II SUPERCONDUCTORS
Authors: TINH BUI DUC , THU LE MINH
Published: July 2012

We use the time-dependent Ginzburg–Landau to calculate AC fluctuation conductivity in type-II superconductor in 2D model under magnetic field. Thermal fluctuations are assumed to be strong enough to melt the Abrikosov vortex lattice created by the magnetic field into a vibrating vortex liquid and marginalize the effects of the vortex pinning by inhomogeneities. The nonlinear interaction term in dynamics is treated within self-consistent Gaussian approximation. We obtain expressions the complex conductivity and resistivity summing all Landau levels which are applicable essentially to whole liquid phase and are compared to experimental data on high-Tc superconductor Bi 2 Sr 2 CaCu 2 O 8+δ.
WAVE-RELAXATION DUALITY OF HEAT PROPAGATION IN FERMI–PASTA–ULAM CHAINS
Authors: GUSEV ANDREI A. , LURIE SERGEY A.
Published: July 2012

In our recent work [Gusev and Lurie, Int. J. Mod. Phys. B26 (2012) 125003], we have presented the theory of spacetime elasticity. The theory advocates its own law of heat conduction in solids, involving both wave and relaxation (diffusion) modes of heat propagation. Here we use that heat conduction law — together with the classical Fourier's and Maxwell–Cattaneo laws — to analyze the temperature dynamics occurring in Fermi–Pasta–Ulam (FPU-β) chains. We focus on the acoustic limit and use a combination of the Langevin and molecular dynamics to study the corresponding temperature decay functions. We have found that all the three laws suit well for describing the high-temperature, exponential-form temperature decay functions. However, at low temperatures the wave dynamics becomes prevailing and it is only the spacetime-elasticity heat conduction law that provides the appropriate functional forms. At all the temperatures and wavelengths studied, the observed temperature dynamics is anomalous, and we discuss both theoretical and practical implications of such anomalous behavior
ANALYSIS OF THERMAL EXPANSIVITY OF SOLIDS UNDER HIGH PRESSURES
Authors: SUNIL K. , SINGH P. K. , SHARMA B. S.
Published: July 2012

For investigating the thermal expansivity of solids under high pressures we have developed a formulation using the relationship between the reciprocal of pressure derivative of bulk modulus and the ratio of pressure and bulk modulus. The formulation presented here satisfies the boundary conditions both at zero-pressure and also in the limit of infinite pressure at extreme compression. A physically acceptable relationship has been obtained between the Anderson–Grüneisen parameter and the pressure derivatives of bulk modulus. The formulation has been applied to determine the pressure dependence of thermal expansivity of NaCl , MgO and the earth lower mantle minerals.
GROWTH OF Cu2ZnSn(S,Se)4 THIN FILMS BY A SIMPLE ECO-FRIENDLY SOLUTION ROUTE METHOD
Authors: ZHANG H. , LI Z. Q. , CHEN Y. R. , LI J. J. , SUN Z. , YANG Z. , HUANG S. M.
Published: July 2012

A simple and hydrazine-free solution-based approach for depositing Cu2ZnSnS4 (CZTS) and Cu2ZnSn(S,Se)4 (CZTSSe) absorber layers is reported. The process involves incorporating metal salts (Cu(CH3COO)2, Zn(CH3COO)2, SnCl2) and thiourea into a single pyridine-based solution, spin-coating a precursor film, and sulfurizing with sulfur powders or selenizing using Se pellets in an inert atmosphere, to form the desired CZTS or CZTSSe films. X-ray diffraction and Raman spectra studies show that kesterite CZTS and CZTSSe are formed after sulfurization and selenization, respectively. The selenized CZTSSe displays higher crystallinity than the sulfurized CZTS. Photovoltaic devices (glass/ Mo /CZTSSe/ CdS /i- ZnO /n- ZnO /A) employing the solution precursor selenized at 500°C have yielded power conversion efficiency of 1.44% under AM 1.5 illumination.
EFFECTS OF α-Al2O3 NANOADDITIVE ON THE PROPERTIES OF CERAMIC COATINGS PREPARED IN BORATE ELECTROLYTE BY MICRO-ARC OXIDATION
Authors: LI H. X. , ZHU H. H. , WU X. , JI Z. G.
Published: July 2012

Ceramic coatings have been synthesized on 6063 aluminum alloy by micro-arc oxidation (MAO) technique in the solution of Na2B4O7 electrolyte with and without α- Al2O3 nanoadditive. Effects of α- Al2O3 nanoadditive on the phase composition, micro-structure, micro-hardness, adhesion and wear resistance of the prepared ceramic coatings have been investigated in this paper. The phase composition and microstructure of the MAO coatings were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDX) analyses, respectively. Micro-hardness, adhesion and tribological and wear tests were also performed. The results showed that the α- Al2O3 nanoadditive doped in the electrolyte had great influence on the structural and mechanical properties of the ceramic coatings.
STRESS-RELIEF SOLUTIONS FOR BRITTLE TiB2 COATINGS
Authors: BULBUL FERHAT , EFEOGLU IHSAN
Published: July 2012

Engineering applications of TiB 2 coatings are limited because of the brittle nature of interfacial bonds on the substrate surfaces, although they have many major properties such as high hardness, high wear and high temperature strength. To overcome this drawback, many researchers have studied over many years and their efforts have taken several forms such as the rotation of substrate, heating treatment during deposition or after deposition, application of positive bias voltage to the substrate, the introduction of transition elements as an interlayer, gradient or multilayer or composite strengthening, and the optimization studies performed by changing deposition process types and/or process parameters such as working gas and bias voltage. The purpose of this paper is to discuss these solutions proposed or developed by researchers against the limited use of TiB 2 coatings due to its brittleness and low adhesion. From the results reported in literature, it is concluded that the best solution in order to produce non-brittle TiB 2 based film well adherent to substrate is the use of pulsed-dc deposition technology provided that the process parameters are tuned to give an appropriate composition and/or a coating design. Furthermore, the TiB 2 based coatings with multiphase layers seem to give better results respect to adherence.
VAN DER WAALS FRICTION: A HAMILTONIAN TEST-BED
Authors: BARTON GABRIEL
Published: July 2012

In the van der Waals regime (neglecting relativity and retardation), we find the power P generated by friction between two Drude-modelled dissipative half-spaces, at fixed separation and relative speed u, admitting only low u and low temperatures. This requires only elementary quantum mechanics; but the results can serve as partial checks on calculations in the fully retarded Casimir regime. They also raise questions regarding (i) the frequency-distribution of P; (ii) the status of predictions about Casimir forces generally, insofar as they feature parameters like conductivities with their empirical temperature-dependence; and (iii) calculations of heat transfer, insofar as they assume fluctuations in the two bodies to be uncorrelated.
QUANTUM CORRECTIONS TO GRAVITY AND THEIR IMPLICATIONS FOR COSMOLOGY AND ASTROPHYSICS
Authors: FABRIS JULIO C. , DE OLIVEIRA PAULO L. C. , RODRIGUES DAVI C. , VELASQUEZ-TORIBIO ALAN M. , SHAPIRO ILYA L.
Published: July 2012

The quantum contributions to the gravitational action are relatively easy to calculate in the higher derivative sector of the theory. However, the applications to the post-inflationary cosmology and astrophysics require the corrections to the Einstein-Hilbert action and to the cosmological constant, and those we can not derive yet in a consistent and safe way. At the same time, if we assume that these quantum terms are covariant and that they have relevant magnitude, their functional form can be defined up to a single free parameter, which can be defined on the phenomenological basis. It turns out that the quantum correction may lead, in principle, to surprisingly strong and interesting effects in astrophysics and cosmology .
COMPARISON BETWEEN EXPERIMENT AND THEORY FOR THE THERMAL CASIMIR FORCE
Authors: KLIMCHITSKAYA G. L. , BORDAG M. , MOSTEPANENKO V. M.
Published: July 2012

We analyze recent experiments on measuring the thermal Casimir force with account of possible background effects. Special attention is paid to the validity of the proximity force approximation (PFA) used in the comparison between the experimental data and computational results in experiments employing a sphere-plate geometry. The PFA results are compared with the exact results where they are available. The possibility to use fitting procedures in theory-experiment comparison is discussed. On this basis we reconsider experiments exploiting spherical lenses of centimeter-size radii.
REPULSIVE CASIMIR EFFECTS
Authors: MILTON K. A. , ABALO E. K. , PARASHAR PRACHI , POURTOLAMI NIMA , BREVIK IVER , ELLINGSEN S. Å.
Published: July 2012

Like Casimir's original force between conducting plates in vacuum, Casimir forces are usually attractive. But repulsive Casimir forces can be achieved in special circumstances. These might prove useful in nanotechnology. We give examples of when repulsive quantum vacuum forces can arise with conducting materials.
NEW CONSTRAINTS ON YUKAWA-TYPE INTERACTIONS FROM THE CASIMIR EFFECT
Authors: MOSTEPANENKO V. M. , BEZERRA V. B. , KLIMCHITSKAYA G. L. , ROMERO C.
Published: July 2012

Measurements of the Casimir force are used to obtain stronger constraints on the parameters of hypothetical interactions predicted in different unification schemes beyond the Standard Model. We review new strong constraints on the Yukawa-type interactions derived during the last two years from recent experiments on measuring the lateral Casimir force, Casimir force in configurations with corrugated boundaries and the Casimir-Polder force. Specifically, from measurements of the lateral Casimir force compared with the exact theory the strengthening of constraints up to a factor of 24 millions was achieved. We also discuss further possibilities to strengthen constraints on the Yukawa interactions from the Casimir effect.
SCALAR CASIMIR ENERGIES OF TETRAHEDRA
Authors: ABALO E. K. , MILTON K. A. , KAPLAN L.
Published: July 2012

New results for scalar Casimir self-energies arising from interior modes are presented for the three integrable tetrahedral cavities. Since the eigenmodes are all known, the energies can be directly evaluated by mode summation, with a point-splitting regulator, which amounts to evaluation of the cylinder kernel. The correct Weyl divergences, depending on the volume, surface area, and the corners, are obtained, which is strong evidence that the counting of modes is correct. Because there is no curvature, the finite part of the quantum energy may be unambiguously extracted. Dirichlet and Neumann boundary conditions are considered and systematic behavior of the energy in terms of geometric invariants is explored.
BOUNDARY CONDITIONS IN THE DIRAC APPROACH TO GRAPHENE DEVICES
Authors: BENEVENTANO C.G. , SANTANGELO E.M.
Published: July 2012

We study a family of local boundary conditions for the Dirac problem corresponding to the continuum limit of graphene, both for nanoribbons and nanodots. We show that, among the members of such family, MIT bag boundary conditions are the ones which are in closest agreement with available experiments. For nanotubes of arbitrary chirality satisfying these last boundary conditions, we evaluate the Casimir energy via zeta function regularization, in such a way that the limit of nanoribbons is clearly determined.
THE CASIMIR EFFECT IN THE SPHERE-PLANE GEOMETRY
Authors: CANAGUIER-DURAND ANTOINE , GUÉROUT ROMAIN , MAIA NETO PAULO A. , LAMBRECHT ASTRID , REYNAUD SERGE
Published: July 2012

We present calculations of the Casimir interaction between a sphere and a plane, using a multipolar expansion of the scattering formula. This configuration enables us to study the nontrivial dependence of the Casimir force on the geometry, and its correlations with the effects of imperfect reflection and temperature. The accuracy of the Proximity Force Approximation (PFA) is assessed, and is shown to be affected by imperfect reflexion. Our analytical and numerical results at ambient temperature show a rich variety of interplays between the effects of curvature, temperature, finite conductivity, and dissipation.
PRECISION MEASUREMENT OF THE CASIMIR FORCE FOR Au USING A DYNAMIC AFM
Authors: CHANG C.-C. , BANISHEV A. A. , CASTILLO-GARZA R. , KLIMCHITSKAYA G. L. , MOSTEPANENKO V. M. , MOHIDEEN U.
Published: July 2012

The gradient of the Casimir force between carefully cleaned Au surfaces of a sphere and a plate is measured using a dynamic atomic force microscope in the frequency modulation regime in high vacuum. The electrostatic calibration of the setup did not reveal any effect of patches or surface contaminants. The experimental data for the force gradient are found to be consistent with theory using the plasma model approach over the entire measurement range. The Drude model approach is excluded by the data at separations from 235 to 400 nm at a 67% confidence level.
DEVELOPMENT OF A HIGH-SENSITIVITY TORSION BALANCE TO INVESTIGATE THE THERMAL CASIMIR FORCE
Authors: GRAVESON TODD , RACKSON CHARLES , KIM WOO-JOONG
Published: July 2012

We report development of a high-sensitivity torsion balance to measure the thermal Casimir force. Special emphasis is placed on experimental investigations of a possible surface electric force originating from surface patch potentials that have been recently noticed by several experimental groups. By gaining a proper understanding of the actual contribution of the surface electric force in real materials, we aim to undertake precision force measurements to resolve the Casimir force at finite temperature in real metals, as well as in other semiconducting materials, such as graphene.