bluuebunny/crossref_metadata_2025 huggingface dataset:
Enclave space: a new metageography of development?
Authors: Sidaway James D
Published: August 2007

Nothwithstanding crisis and critique, development remains an enduring frame within which much social and economic transformation is interpreted and envisaged. In the context of arguments about the need for a nuanced spatial vantage point on development, this paper asks what this means in the context of new conjunctures and constellations? It focuses on intensified processes and patterns of uneven development manifest as enclaves. The paper explores these drawing on literatures about Southeast Asia, sub‐Saharan Africa and the Gulf.
Study on Decellularized Porcine Aortic Valve/Poly (3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) Hybrid Heart Valve in Sheep Model
Authors: Wu Song , Liu Ying‐Long , Cui Bin , Qu Xiang‐Hua , Chen Guo‐Qiang
Published: August 2007

Abstract:  To overcome shortcomings of current heart valve prostheses, novel hybrid valves were fabricated from decellularized porcine aortic valves coated with poly (3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate [PHBHHx]). In the mechanical test in vitro, the biomechanical performance of hybrid valve was investigated. In an in vivo study, hybrid valve conduits were implanted in pulmonary position in sheep without cardiopulmonary bypass. Uncoated grafts were used as control. The valves were explanted and examined histologically and biochemically 16 weeks after surgery. The hybrid valve conduits maintained original shapes, were covered by a confluent layer of cells, and had less calcification than uncoated control. The mechanical test in vitro revealed that PHBHHx coating improved tensile strength. The results in vivo indicated that PHBHHx coating reduced calcification and promoted the repopulation of hybrid valve with the recipient's cells resembling native valve tissue. The hybrid valve may provide superior valve replacement with current techniques.
Ultrafiltration Capacity and Peritoneal Fluid Kinetics in Continuous Ambulatory Peritoneal Dialysis Patients
Authors: Zhe Xing‐wei , Tian Xin‐kui , Cheng Lei , Wang Tao
Published: August 2007

Abstract:  Volume control is critical for peritoneal dialysis. Although peritoneal equilibration test (PET) has been used to clarify the peritoneal membrane characteristics, it is not able to adequately predict peritoneal fluid removal and optimize appropriately the dwell time. In the present study, we applied computer simulation and performed a more detailed evaluation of the fluid kinetics in patients with different ultrafiltration (UF) capacity. Patients who used three to four exchanges of 2.27% glucose dialysate per day (poor UF capacity group), and patients who used three to four exchanges of 1.36% glucose dialysate per day (good UF capacity group) to achieve adequate amount of peritoneal fluid removal were included in the present analysis. All included patients were asked to record appropriately their dialysis exchanges for the assessment of their peritoneal fluid transport characteristics. Seventeen continuous ambulatory peritoneal dialysis patients were selected in the present study, nine in poor UF capacity group and eight in good UF capacity group. Patients in poor UF capacity group had significantly higher daily glucose exposure, higher dialysate‐to‐plasma ratio of creatinine (D/P creatinine) values, and higher peritoneal fluid absorption rate, Ke, as compared to patients with good UF capacity. Our results suggest that patients with poor UF capacity have significant higher peritoneal small solute transport rate, and more importantly, higher peritoneal fluid absorption rate as compared to patients with good UF capacity.
Three‐dimensional Culture of Human Nucleus Pulposus Cells in Fibrin Clot: Comparisons on Cellular Proliferation and Matrix Synthesis With Cells in Alginate
Authors: Yang Shu‐Hua , Wu Chang‐Chin , Shih Tiffany Ting‐Fang , Chen Po‐Quang , Lin Feng‐Huei
Published: August 2007

Abstract:  Regeneration of nucleus pulposus (NP) tissue may stop or reverse early intervertebral disk (IVD) degeneration. Cellular proliferation and matrix synthesis can be promoted by incorporation of cells and bioscaffolds. However, insertion of preshaped solid bioscaffolds may damage remaining IVD integrity. Fibrin clots can be introduced in a minimally invasive manner with polymerization in desired three‐dimensional shape and retention of cells. In this study, we investigated the cellular proliferation and matrix synthesis of human NP cells in the fibrin clots in vitro. Monolayer‐expanded cells were embedded in fibrin clot or alginate and were cultivated in vitro for 2 weeks. Increased DNA content and decreased expression of apoptosis stimulating fragment (Fas)‐associated death‐domain protein in fibrin scaffolds suggested higher cellular proliferation and reduced apoptosis. Superior proteoglycan synthesis was found in fibrin scaffolds. As expression of collagens I and X increased and SOX9 expression decreased, fibrin scaffolds tended to promote fibrotic transformation and inhibit chondrogenesis. Adjustments of fibrin preparations are needed to make it more suitable for IVD regeneration.
The Adsorption of Vancomycin by Polyacrylonitrile, Polyamide, and Polysulfone Hemofilters
Authors: Tian Qi , Gomersall Charles D. , Leung Patricia P.N. , Choi Gordon Y.S. , Joynt Gavin M. , Tan Perpetua E. , Wong April S.Y.
Published: August 2007

Abstract:  The aim of this study was to characterize vancomycin adsorption by polyacrylonitrile (PAN), polyamide, and polysulfone hemofilters using an in vitro model of hemofiltration. Vancomycin (36 mg) was added to a blood‐crystalloid mixture of known volume (target concentration of 50 mg/L) and pumped around a closed circuit. Adsorption, which was calculated from the fall in concentration over 120 min, was significantly greater by 0.6‐m2 PAN filters (10.08 ± 2.26 mg) than by 0.6‐m2 polyamide (5.20 ± 1.82 mg) or 0.7‐m2 polysulfone (4.80 ± 2.40 mg) filters (P < 0.05). Cumulative adsorption was not changed by the addition of 500‐mL lactated Ringer's solution (to reduce the circulating vancomycin concentration). These data show that although adsorption of vancomycin by PAN, polyamide, and polysulfone hemofilters occurs, the absolute adsorption is small. Adsorption is dependent on filter material and is not reversed by a decrease in circulating concentration.
Effect of Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) Nanofiber Matrices Cocultured With Hair Follicular Epithelial and Dermal Cells for Biological Wound Dressing
Authors: Han Insook , Shim Kyung Jin , Kim Jung Yong , Im Sang Uk , Sung Young Kwan , Kim Moonkyu , Kang Inn‐Kyu , Kim Jung Chul
Published: August 2007

Abstract:  We tested the effects on the early‐stage wound healing of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) nanofiber matrices cultured with hair follicular cells. PHBV only, PHBV/collagen, and PHBV/gelatin at a 7/3 weight ratio were produced by electrospinning, and their in vitro cell culture and in vivo wound healing as biological dressings were examined. In cell attachment and growth on matrices, dermal sheath (DS) cells attached to hydrophilic PHBV/collagen and PHBV/gelatin faster than hydrophobic PHBV at the early incubation stage (up to 6 h). From 6‐ to 24‐h incubation, PHBV/collagen showed the best results in cell culture. Furthermore, PHBV/collagen cocultured for 3–5 days with DS and epithelial outer root sheath (ORS) cells expressed more extracellular materials, such as type I collagen, elastin, and α‐smooth muscle actin, than cocultured PHBV with the same cells. However, there was no significant difference between PHBV and PHBV/collagen in the amounts of cytokeratin 8 expressed. Grafting of PHBV and PHBV/collagen matrices cocultured with ORS/DS cells for 3–5 days showed that PHBV promoted wound closure and re‐epithelization more obviously than PHBV/collagen in both cocultured matrices and matrices alone. Cocultured matrices would heal wounds better than the corresponding matrices alone. Thus, PHBV cocultured with ORS/DS cells could be used as a cell‐seeded biological dressing, thereby reducing preparation time as well as regenerating the epidermis efficiently during the early stage of wound healing.
Retromolar Ridge in Edentulous Patients: Clinical Considerations
Authors: Pietrokovski Jaime , Kaffe Israel , Arensburg Baruch
Published: August 2007

Purpose:
A removable denture base should cover the mandibular retromolar regions to provide proper basal seal and denture function in edentulous patients. The bony residual ridge form, attached muscles, and covering mucosa provide support, stability, and retention of the planned prosthesis. There is insufficient information regarding bone anatomy, mucosal tissues, and muscles in the retromolar region after tooth loss. The purpose of this study was to examine the tissue morphology in the mandibular retromolar area of edentulous subjects and report on the clinical inferences in prosthetic and implant dentistry.

Materials and Methods:
Specimens included 75 edentulous and eight dentate dry mandibles examined by macroscopic observations and linear measurements for size determinants in the left and right retromolar regions. Buccolingual histological sections of the mandibular retromolar region from seven edentulous subjects were also examined. The specimens were from the Department of Anatomy and Anthropology, Sackler School of Medicine, Tel Aviv University.

Results:
The specimens evaluated in this study revealed that a bony retromolar ridge can be large, with adjacent muscles attached several millimeters below its edentulous bone crest, or small, with muscles attached to the buccal and lingual bone crests. In all examined jaws, bony mylohyoid ridges (MR) and buccal shelves with affixed muscle fibers were present regardless of the remaining mandibular bone form and size.

Conclusions:
The mylohyoid muscles attached to MRs and the buccinator muscles affixed to buccal bony shelves are some of the barriers to the chronic but limited bone resorption, following tooth loss, time of edentulism, systemic factors, and denture wear.
Synthesis and Photoluminescence Properties of Eu3+‐Doped Calcium Phosphates
Authors: Kim Eun Jin , Choi Sung‐Woo , Hong Seong‐Hyeon
Published: August 2007

Eu3+‐doped (1–12 mol%) calcium hydroxyapatite (HA) and β‐tricalcium phosphate (β‐TCP) powders were synthesized by a precipitation method and their photoluminescence (PL) properties were investigated. Eu has a limited solubility in HA and Eu2O3 was detected by X‐ray diffraction above 3% doping, whereas a nearly single β‐phase was obtained up to 6% doping in TCP but EuPO4 appeared in the 12% Eu‐doped specimen. Electron spin resonance measurement confirmed that europium ions exist as Eu3+ in both samples. Eu3+‐doped HA exhibited a strong emission at 575 nm with several minor peaks at 610–640 nm and Eu3+‐doped TCP had an intense emission at 613 nm with secondary peaks at 590–600 nm, which were consistent with the earlier reports determined at low temperatures. In Eu‐doped TCP, the PL intensity increased with increasing calcination temperature without phase transformation. The more the Eu added, the higher the PL intensity obtained in both cases.
Synthesis, Structure, and Electrochemical Characterization of Nanocrystalline Tantalum and Tungsten Nitrides
Authors: Choi Daiwon , Kumta Prashant N.
Published: August 2007

Nanocrystalline tantalum and tungsten nitrides were synthesized by a two‐step ammonolysis reaction of transition metal chlorides. The first step involves ammonolysis of tantalum and tungsten chlorides at room temperature using anhydrous chloroform as the solvent. A second step consists of heat treatment of these as‐prepared powders under anhydrous NH3 atmosphere leading to the formation of tantalum and tungsten nitride nanocrystallites at relatively low temperature (600°–675°C). The ammonolysis, nitridation, structure, morphology, surface area, density, and electronic conductivity of the nitrides obtained were studied and characterized. The electrochemical responses of these nitrides were also measured by cyclic voltammetry using 1M KOH electrolyte.
Nap and melatonin‐induced changes in hippocampal activation and their role in verbal memory consolidation
Authors: Gorfine Tali , Yeshurun Yaara , Zisapel Nava
Published: August 2007

Abstract:  Overnight sleep contributes to memory consolidation; even a short nap improves memory performance. Such improvement has been linked to hippocampal activity during sleep. Melatonin has been shown to affect the human hippocampus and to induce ‘sleep like’ changes in brain activation. We therefore conducted and compared two functional magnetic resonance imaging studies: the first study assessed the effect of a 2‐hr mid‐day nap versus an equal amount of wakefulness on a verbal memory task (unrelated word pair association); the second assessed the effect of melatonin versus placebo (both conditions without nap) on a similar task. We report that following a nap relative to wakefulness, successful retrieval‐related activation in the parahippocampus is decreased. A smaller decrease is seen in wakefulness with melatonin but not placebo. In parallel, an improvement in verbal memory recall was found after a nap compared with wakefulness but not with melatonin during wakefulness compared with placebo. Our findings demonstrate effects of melatonin that resemble those of sleep on verbal memory processing in the hippocampus thus suggesting that melatonin, like sleep, can initiate offline plastic changes underlying memory consolidation; they also suggest that concomitant rest without interferences is necessary for enhanced performance.
Development of a new probe for specific and sensitive detection of ‘Candidatus Phytoplasma mali’ in inoculated apple trees
Authors: Aldaghi M. , Massart S. , Roussel S. , Jijakli M.H.
Published: August 2007

A new TaqMan minor groove binding (MGB) probe and new PCR conditions were designed for quick, specific and sensitive detection of ‘Candidatus Phytoplasma mali’. The new probe can distinguish a single mismatch between ‘Ca. P. mali’ and ‘Candidatus Phytoplasma prunorum’, this constituting an improvement over a previously published method. In our study, the relative position of the mismatch in the MGB probe influenced greatly the specificity of detection. Our new real‐time PCR protocol was able to detect one plasmid copy in water and 100 copies in healthy plant DNA extracts. The sensitivity of this new real‐time PCR method, three other real‐time PCR protocols and a conventional PCR with fU5/rU3 primers was compared. Periwinkles and MM106 rootstocks were grafted with infected material and surveyed over time by symptom observation, conventional PCR and real‐time PCR. Phytoplasma infection was detected by symptom observation in all periwinkles within 4 months and in 75% of the MM106 rootstocks by the end of 7 months. Conventional PCR detected phytoplasma infection in all periwinkles within 4 months and in all MM106 rootstocks within 7 months. Best results were obtained by our real‐time PCR, which detected phytoplasma infection in all grafted plants within 3 months after inoculation.
Effect of Rising and Falling K Profiles on SCC Growth Rates in High-Temperature Water
Authors: Andresen Peter L. , Morra Martin M.
Published: July 2007

Effects of rising and falling stress intensity factor (K) profiles on the stress corrosion cracking (SCC) growth rates of stainless steel and nickel alloys has been studied in high-temperature water. Sophisticated test control software was used that changes loading (P) based on crack length (a) to achieve a specific K trajectory by controlling dK∕da, not simply dP∕dt. The majority of SCC problems develop adjacent to welds, which have a complex residual stress profile versus wall thickness. This, coupled with the dependence of K on crack length, causes K to change as the crack grows, not per se with time (t). The effect of the rate of change in K on crack tip strain rate and the associated crack growth rate is discussed, along with the repercussions to understanding and dispositioning SCC response.
Relationship between fundamental and formant frequencies in voice preference
Authors: Assmann Peter F. , Nearey Terrance M.
Published: July 2007

Covariation in the size of laryngeal and vocal tract structures leads to a moderate correlation between fundamental frequency (F0) and formant frequencies (FFs) in natural speech. A method of adjustment procedure was used to test whether listeners prefer combinations of F0 and FFs that reflect this covariation. Vowel sequences spoken by two men and two women were processed by the STRAIGHT vocoder to construct three sets of frequency-shifted continua. The distributions of “best choice” responses in all three experiments confirm that listeners prefer coordinated patterns of F0 and FF similar to those of natural speech.
Adaptive microphone array for unknown desired speaker’s transfer function
Authors: Papp Istvan I. , Saric Zoran M. , Jovicic Slobodan T. , Teslic Nikola Dj.
Published: July 2007

The main drawback of minimum variance distortionless response (MVDR) beamformer is the cancellation of the desired speech signal and its degradation in multi-path wave propagation environment. To make the adaptive algorithm robust against room reverberation and to prevent desired signal cancellation an estimation of unknown desired speaker’s transfer function was proposed. The estimation is based on the signal and the interference covariance matrices. The estimated transfer function is then applied to the MVDR beamformer. The proposed algorithm was tested on a simulated room with reverberation. The results showed better quality of the restored speech compared to some typical adaptive algorithms.
Observations of potential acoustic cues that attract sperm whales to longline fishing in the Gulf of Alaska
Authors: Thode Aaron , Straley Janice , Tiemann Christopher O. , Folkert Kendall , O’Connell Victoria
Published: July 2007

Sperm whales (Physeter macrocephalus) have learned to remove fish from demersal longline gear deployments off the eastern Gulf of Alaska, and are often observed to arrive at a site after a haul begins, suggesting a response to potential acoustic cues like fishing-gear strum, hydraulic winch tones, and propeller cavitation. Passive acoustic recorders attached to anchorlines have permitted continuous monitoring of the ambient noise environment before and during fishing hauls. Timing and tracking analyses of sperm whale acoustic activity during three encounters indicate that cavitation arising from changes in ship propeller speeds is associated with interruptions in nearby sperm whale dive cycles and changes in acoustically derived positions. This conclusion has been tested by cycling a vessel engine and noting the arrival of whales by the vessel, even when the vessel is not next to fishing gear. No evidence of response from activation of ship hydraulics or fishing gear strum has been found to date.
Variation in chick-a-dee calls of tufted titmice,Baeolophus bicolor: Note type and individual distinctiveness
Authors: Owens Jessica L. , Freeberg Todd M.
Published: July 2007

The chick-a-dee call of chickadee species (genus Poecile) has been the focus of much research. A great deal is known about the structural complexity and the meaning of variation in notes making up calls in these species. However, little is known about the likely homologous “chick-a-dee” call of the closely related tufted titmouse, Baeolophus bicolor. Tufted titmice are a prime candidate for comparative analyses of the call, because their vocal and social systems share many characteristics with those of chickadees. To address the paucity of data on the structure of chick-a-dee calls of tufted titmice, we recorded birds in field and aviary settings. Four main note types were identified in the call: Z, A, Dh, and D notes. Several acoustic parameters of each note type were measured, and statistical analyses revealed that the note types are acoustically distinct from one another. Furthermore, note types vary in the extent of individual distinctiveness reflected in their acoustic parameters. This first step towards understanding the chick-a-dee call of tufted titmice indicates that the call is comparable in structure and complexity to the calls of chickadees.
Cylindrical Block Copolymer Micelles and Co-Micelles of Controlled Length and Architecture
Authors: Wang Xiaosong , Guerin Gerald , Wang Hai , Wang Yishan , Manners Ian , Winnik Mitchell A.
Published: August 2007

Block copolymers consist of two or more chemically different polymers connected by covalent linkages. In solution, repulsion between the blocks leads to a variety of morphologies, which are thermodynamically driven. Polyferrocenyldimethylsilane block copolymers show an unusual propensity to forming cylindrical micelles in solution. We found that the micelle structure grows epitaxially through the addition of more polymer, producing micelles with a narrow size dispersity, in a process analogous to the growth of living polymer. By adding a different block copolymer, we could form co-micelles. We were also able to selectively functionalize different parts of the micelle. Potential applications for these materials include their use in lithographic etch resists, in redox-active templates, and as catalytically active metal nanoparticle precursors.
Defusing the Childhood Vocabulary Explosion
Authors: McMurray Bob
Published: August 2007

During the second year of life, the rate at which children acquire new words accelerates dramatically. This has led the field of language acquisition to posit specialized mechanisms that leverage the few words learned in the initial slow phase for faster vocabulary growth later. Simulations and mathematical analysis demonstrate that specialized cognitive changes are unnecessary. The acceleration in lexical acquisition is a necessary by-product of learning if (i) multiple words are learned in parallel and (ii) words are distributed such that there are few words that can be acquired quickly and many difficult ones.
The Phenolic Diterpene Totarol Inhibits Multidrug Efflux Pump Activity in
Staphylococcus aureus
Authors: Smith Eileen C. J. , Kaatz Glenn W. , Seo Susan M. , Wareham Neale , Williamson Elizabeth M. , Gibbons Simon
Published: July 2007

The phenolic diterpene totarol had good antimicrobial activity against effluxing strains of
Staphylococcus aureus
. Subinhibitory concentrations reduced the MICs of selected antibiotics, suggesting that it may also be an efflux pump inhibitor (EPI). A totarol-resistant mutant that overexpressed
norA
was created to separate antimicrobial from efflux inhibitory activity. Totarol reduced ethidium efflux from this strain by 50% at 15 μM (1/4× MIC), and combination studies revealed marked reductions in ethidium MICs. These data suggest that totarol is a NorA EPI as well as an antistaphylococcal antimicrobial agent.
High-Throughput Screens for Small-Molecule Inhibitors ofPseudomonas aeruginosaBiofilm Development
Authors: Junker Lauren M. , Clardy Jon
Published: July 2007

Pseudomonas aeruginosais both a model biofilm-forming organism and an opportunistic pathogen responsible for chronic lung infections in cystic fibrosis (CF) patients and infections in burn patients, among other maladies. Here we describe the development of an efficient high-throughput screen to identify small-molecule modulators of biofilm formation. This screen has been run with 66,095 compounds to identify those that prevent biofilm formation without affecting planktonic bacterial growth. The screen is a luminescence-based attachment assay that has been validated with several strains ofP. aeruginosaand compared to a well-established but low-throughput crystal violet staining biofilm assay.P. aeruginosastrain PAO1 was selected for use in the screen both because it forms robust biofilms and because genetic information and tools are available for the organism. The attachment-inhibited mutant, strain PAO1 ΔfliC, was used as a screening-positive control. We have also developed and validated a complementary biofilm detachment assay that can be used as an alternative primary screen or secondary screen for the attachment screening-positive compounds. We have determined the potencies of 61 compounds against biofilm attachment and have identified 30 compounds that fall into different structural classes as biofilm attachment inhibitors with 50% effective concentrations of less than 20 μM. These small-molecule inhibitors could lead to the identification of their relevant biofilm targets or potential therapeutics forP. aeruginosainfections.
Seroincidence of Recent Human Immunodeficiency Virus Type 1 Infections in China
Authors: Xiao Yao , Jiang Yan , Feng Jigang , Xu Wenyan , Wang Minjie , Funkhouser Ellen , Vermund Sten H. , Jia Yujiang
Published: August 2007

A subtype B, E, and D immunoglobulin G capture immunoassay shows promise as a tool for estimating human immunodeficiency virus type 1 seroincidence from cross-sectional surveys, but the test-specific limitations suggest that an adjustment is necessary, and further validation of the assay with populations with divergent subtypes is needed.
Polymorphisms in
gyrA
and
gyrB
Genes among
Mycobacterium avium
subsp.
paratuberculosis
Type I, II, and III Isolates
Authors: Castellanos E. , Aranaz A. , Romero B. , de Juan L. , Alvarez J. , Bezos J. , Rodríguez S. , Stevenson K. , Mateos A. , Domínguez L.
Published: August 2007

The analysis of the
gyrA
and
gyrB
genes of a panel of
Mycobacterium avium
subsp.
paratuberculosis
isolates from types I, II, and III detected type-specific single nucleotide polymorphisms. Based on these results, we developed a PCR and restriction enzyme analysis to discriminate type I and III isolates. The application of this technique would be the unique strategy to characterize these strains when there is not enough bacterial growth to perform pulsed-field gel electrophoresis and IS
900
restriction fragment length polymorphism.
Induction of Autophagy Does Not Affect Human Rhinovirus Type 2 Production
Authors: Brabec-Zaruba Marianne , Berka Ursula , Blaas Dieter , Fuchs Renate
Published: August 2007

Induction of autophagy has been shown to be beneficial for the replication of poliovirus, a phenomenon that might also apply for other picornaviruses. We demonstrate that de novo synthesis of human rhinovirus type 2 (HRV2), an HRV of the minor receptor group, is unaffected by tamoxifen, rapamycin, and 3-methyladenine (3-MA), drugs either stimulating (tamoxifen and rapamycin) or inhibiting (3-MA) autophagic processes. Furthermore, LC3-positive vesicles (i.e., autophagosomes) are not induced upon infection. Therefore, multiplication of this particular picornavirus is not dependent on autophagy.
Early Establishment and Antigen Dependence of Simian Immunodeficiency Virus-Specific CD8+T-Cell Defects
Authors: Mueller Yvonne M. , Petrovas Constantinos , Do Duc H. , Altork Susan R. , Fischer-Smith Tracy , Rappaport Jay , Altman John D. , Lewis Mark G. , Katsikis Peter D.
Published: August 2007

Differentiation and survival defects of human immunodeficiency virus (HIV)-specific CD8+T cells may contribute to the failure of HIV-specific CD8+T cells to control HIV replication. It is not known, however, whether simian immunodeficiency virus (SIV)-infected rhesus macaques show comparable defects in these virus-specific CD8+T cells or when such defects are established during infection. Peripheral blood cells from acutely and chronically infected rhesus macaques were stained ex vivo for memory subpopulations and examined by in vitro assays for apoptosis sensitivity. We show here that SIV-specific CD8+T cells from chronically SIV infected rhesus macaques show defects comparable to those observed in HIV infection, namely, a skewed CD45RA−CD62L−effector memory phenotype, reduced Bcl-2 levels, and increased levels of spontaneous and CD95-induced apoptosis of SIV-specific CD8+T cells. Longitudinal studies showed that the survival defects and phenotype are established early in the first few weeks of SIV infection. Most importantly, they appear to be antigen driven, since most probably the loss of epitope recognition due to viral escape results in the reversal of the phenotype and reduced apoptosis sensitivity, something we observed also for animals treated with antiretroviral therapy. These findings further support the use of SIV-infected rhesus macaques to investigate the phenotypic changes and apoptotic defects of HIV-specific CD8+T cells and indicate that such defects of HIV-specific CD8+T cells are the result of chronic antigen stimulation.
c-Myc and Sp1 Contribute to Proviral Latency by Recruiting Histone Deacetylase 1 to the Human Immunodeficiency Virus Type 1 Promoter
Authors: Jiang Guochun , Espeseth Amy , Hazuda Daria J. , Margolis David M.
Published: August 2007

Histone deacetylase (HDAC) inhibitors such as valproic acid (VPA) induce the expression of quiescent proviral human immunodeficiency virus type 1 (HIV-1) and may deplete proviral infection in vivo. To uncover novel molecular mechanisms that maintain HIV latency, we sought cellular mRNAs whose expression was diminished in resting CD4
+
T cells of HIV-1-infected patients exposed to VPA. c-Myc was prominent among genes markedly downregulated upon exposure to VPA. c-Myc expression repressed HIV-1 expression in chronically infected cell lines. Chromatin immunoprecipitation (ChIP) assays revealed that c-Myc and HDAC1 are coordinately resident at the HIV-1 long terminal repeat (LTR) promoter and absent from the promoter after VPA treatment in concert with histone acetylation, RNA polymerase II recruitment, and LTR expression. Sequential ChIP assays demonstrated that c-Myc, Sp1, and HDAC1 coexist in the same DNA-protein complex at the HIV promoter. Short hairpin RNA inhibition of c-Myc reduces both c-Myc and HDAC1 occupancy, blocks c-Myc repression of Tat activation, and increases LTR expression. These results expand the understanding of mechanisms that recruit HDAC and maintain the latency of HIV-1, suggesting novel therapeutic approaches against latent proviral HIV infection.
Complexes between Herpes Simplex Virus Glycoproteins gD, gB, and gH Detected in Cells by Complementation of Split Enhanced Green Fluorescent Protein
Authors: Avitabile Elisa , Forghieri Cristina , Campadelli-Fiume Gabriella
Published: August 2007

The interactions between herpes simplex virus gD and its nectin1 receptor or between gD, gB, and gH were analyzed by complementation of the N and C portions of split enhanced green fluorescent protein (EGFP) fused to the glycoproteins. The gD
N
-Nect
C
complex was readily detected; the gD
N
-gC
C
complex was undetectable, highlighting the specificity of the assay. Split EGFP complementation was detected between proteins designated gD
N
+gH
C
, gD
N
+gB
C
, and gH
N
+gB
C
+wtgD (gB was deleted of endocytosis motifs), both in cells transfected with two-tree glycoproteins and in syncytia. The in situ assay provides evidence that gD interacts with gH and gB independently of each other and supports a model whereby gH and gB in complex exert their activities to gD.
Effects of size, shape, and edge on vegetation in remnants of the upland boreal mixed-wood forest in agro-environments of Alberta, Canada
Authors: Gignac L. Dennis , Dale Mark R.T.
Published: July 2007

Forty-one remnants of the aspen-dominated upland forest in three subregions of the dry boreal mixed-wood in Alberta were studied to determine effects of fragment size and shape on native and alien plant species richness and abundance in agro-environments. The percent cover of all vascular plant species was visually estimated in 5 m diameter circular plots along transects that covered the length and the width of each fragment. A subset of 12 of the largest fragments (>900 m2) that had distinct interiors (portions of the fragment >15 m from any edge) was used to measure edge effects on the vegetation. Regression analyses revealed significant positive relationships between species richness and area regardless of the subregion. Species richness stabilized in fragments that were larger than 11 ha. Edges did not affect shrub species richness and only affected herbaceous species richness on west- and south-facing aspects. Shrub abundance decreased and herb abundance increased up to 20 m from the edges regardless of orientation. Edges did not support a different suite of species than interiors, although several species occurred more frequently in the interior than along the edges. Alien species richness and abundance reached their highest values between 5 and 15 m from the edge, and some of those species could be found up to 40 m from the edge. Although larger fragments generally supported more alien species than smaller fragments, the smallest fragments had the greatest number of species per metre squared. Results from this study indicated that it would be preferable to conserve larger woodlots rather then several smaller woodlots on the landscape.
The potential for ploidy level increases and decreases in Crataegus (Rosaceae, Spiraeoideae, tribe Pyreae)
Authors: Talent Nadia , Dickinson Timothy A.
Published: August 2007

Unlike their diploid relatives, some triploid and tetraploid Crataegus frequently produce unreduced megagametophytes. In all cases, pollination is required for successful seed set, but in polyploids, endosperm formation can involve fertilization by either one or both sperm. Apomixis, in which the egg develops parthenogenetically, is widely documented in polyploid Crataegus, and as in many other groups with gametophytic apomeiosis, fertilization of unreduced eggs can also occur. Reciprocal pollinations were made between diploids, triploids, and tetraploids belonging to five taxonomic series in the genus to evaluate opportunities for gene flow between ploidy levels. The ploidy levels of embryo and endosperm in mature seeds, estimated from flow-cytometric DNA measurements, indicate the meiotic or apomeiotic origin of the megagametophyte and whether fertilization has occurred. These experiments demonstrated that although some tetraploids maintain near-obligate apomixis when supplied with pollen from diploids, others produced seeds containing embryos ranging from diploid to hexaploid. Allotriploid embryos were produced when a diploid was provided with pollen from tetraploids. A triploid produced tetraploid embryos when pollinated by a diploid and pentaploid embryos when pollinated by a tetraploid. Gametophytic apomixis in Crataegus thus can be facultative or near-obligate and may be implicated in the formation of interserial hybrids.
Photoperiod, light quality, and irradiance effects on flowering in the alpine and prairie ecotypes of Stellaria longipes
Authors: Kurepin Leonid V. , Walton Linda J. , Reid David M. , Chinnappa C.C. , Pharis Richard P.
Published: August 2007

Plants growing in vegetative shade are subjected to reductions in both red to far-red (R/FR) light ratio and in irradiance levels of photosynthetically active radiation (PAR). In this report we have attempted to uncouple the reduced R/FR ratio- and low PAR-mediated effects of shade on flowering in the ramets of Stellaria longipes Goldie s.l. (Caryophyllaceae) ecotypes collected from alpine “sun” and lower elevation prairie “shade” habitats. Both ecotypes were also tested for their flowering response (defined as the number of open flowers per ramet) to daylength. The alpine ecotype plants can best be classified as day-neutral, whereas prairie ecotype plants require long-days (LD). Under a low PAR of 115 μmol m–2·s–1 given under LD conditions at a reduced (0.7) R/FR ratio, alpine ecotype plants flowered significantly later relative to plants grown under the low PAR at a normal (1.22) R/FR ratio. In contrast, plants of the prairie ecotype flowered earlier under the reduced R/FR ratio combined with the same low PAR. Flower number per ramet differed significantly between the two ecotypes, with alpine ecotype plants developing fewer flowers under a low PAR (109 μmol m–2·s–1 irradiance) relative to a high PAR of 611 μmol m–2·s–1 (both given at a normal R/FR ratio). The prairie ecotype plants responded differently and had similar flower numbers under both low and high PARs at the normal (1.22) R/FR ratio. However, growing the prairie ecotype plants under a reduced R/FR ratio at a low PAR showed a significant increase in number of flowers. In contrast, plants grown under high (2.7) and normal (1.9) R/FR ratios combined with low PAR produced many more flowers than the alpine ecotype. Thus, the two components of shade, reduced R/FR ratio and low PAR can cause distinctly different flowering responses in sun and shade plants of S. longipes.
Devonian–Carboniferous paleogeography and orogenesis, northern Yukon and adjacent Arctic Alaska
Authors: Lane Larry S
Published: July 2007

Surface and subsurface data from northern Yukon document a northward facies transition from shelf carbonates to basinal graptolitic shales and cherts from Late Cambrian to Early Devonian time. Parts of this north-facing continental margin were deformed during separate orogenic events of Early Devonian and Early Carboniferous ages. The first event, the Romanzof Orogeny, is identified in exposures across northwestern Yukon, in adjacent northeastern Alaska, and locally in the subsurface of the Alaska North Slope. It resulted in tight folds, north-directed thrust faults, and intrusion by Late Devonian posttectonic granitic plutons. Notwithstanding the thrust-fault orientations, southward diminution of deformation intensity combined with facies variations suggest that tectonic transport was generally southward. Evidence for an Early Carboniferous event is preserved in the northern Richardson Mountains and locally in the subsurface of the Mackenzie Delta region. It consists of detached open folds and minor thrust faults. Geological and geophysical data from northern Yukon document the location and orientation of the Early Carboniferous deformation front, and define a regional tectonic transport direction toward the south or southeast. This event is a distal foreland element of the Ellesmerian Orogeny (sensu stricto) of the Canadian Arctic Islands and is distinct from the Romanzof event in age, intensity, and extent. Endicott and Lisburne group strata, deposited on a southwest-facing subsiding shelf, overstep rocks deformed by the Romanzof event even as Ellesmerian deformation encroached from the north.
The concept of fecundity regulation in plaice (Pleuronectes platessa) tested on three Irish Sea spawning populations
Authors: Kennedy J , Witthames P R , Nash R DM
Published: July 2007

The fecundity of European plaice (Pleuronectes platessa) in the Irish Sea between 2000 and 2004 was estimated during the spawning season for fish in the three main spawning areas (Liverpool Bay, the Cumbrian coast, and the western Irish Sea) and one small spawning group on the west coast of the Isle of Man. Fecundity was also estimated during September of 2003 and 2004. The aim of this was to assess the variability in fecundity between areas and years in the Irish Sea and also to identify when differences in fecundity become apparent in the maturation cycle. There were variations in fecundity on both the temporal and spatial scales. The greatest variation in fecundity between years occurred in the western Irish Sea, whereas there was no variation between years in the southeastern Irish Sea (Liverpool Bay). There was no difference in fecundity between areas or years during September. The maximum fecundity in plaice is determined by the total weight of the fish at the end of follicle recruitment in the ovary, and differences in the fecundity of each population are the result of different levels of down-regulation in the period between the end of follicle proliferation and spawning.
Evaluating the sensitivity of a trophic mass-balance model (Ecopath) to imprecise data inputs
Authors: Essington Timothy E
Published: July 2007

Ecopath with Ecosim has become the most widely adopted modelling framework to facilitate a more holistic, ecosystem-based approach to fisheries management. I evaluated the sensitivity of Ecopath predictions to uncertainty in input data and determined the extent to which they were improved via the mass-balance constraint. I used nine published Ecopath models as operational models, added error to input variables, and then determined how well Ecopath could uncover the true model structure. I focused on Ecopath's ability to precisely estimate biomass and ecotrophic efficiency (the proportion of a group's total mortality explicitly represented in the model by predation and fishing). Ecopath error predictions were approximately as precise as the input variables, except in cases of tightly linked cycles of food web connections when errors become greatly amplified. The process of model balancing had little effect on the magnitude of prediction errors. Moreover, accurate information about the source of imprecise data had little impact on prediction precision. Ecopath predictions were most sensitive to biomass and production rate input data and only occasionally sensitive to consumption rate and feeding habits data. Taken together, these results suggest that the precision of Ecopath-derived estimates of biomass and ecotrophic efficiency is generally comparable with the precision of the input data.
Precise proton radii from electron scattering
Authors: Sick Ingo
Published: July 2007

We summarize various analyses of the world data on elastic electron scattering for the determination of the most precise charge rms-radius of the proton. We also present the Zemach moments needed for the interpretation of atomic HFS structure and μ-X-ray experiments.PACS Nos.: 13.40.Gp, 13.40.Em, 14.20.Dh
Vacuum polarization in muonic and exotic atoms: the Lamb shift at medium Z and high n
Authors: Korzinin E Yu. , Ivanov V G , Karshenboim S G
Published: July 2007

We present new results on various asymptotics for the Uehling contribution to the energy levels in atomic states in hydrogen-like atoms that have a principal quantum number n with a high value. The results may be applied to conventional atoms (with an orbiting electron) as well as to muonic, pionic, antiprotonic, and other exotic atoms.PACS Nos.: 36.10.Gv, 31.30.Jv
Calculation of the propagation amplitude in the case of a Coulomb interaction via time-independent mean-field theory
Authors: Yekken R , Mekideche F
Published: July 2007

The exact study of many-body microscopic systems is impossible when the number of particles is large (N ≥ 3). Approximate methods are then used. The time-independent mean-field (TIMF) approximation has been proposed for the description of collisions in many-body systems. Collision amplitudes are derived by the use of a variational principle and the choice of trial functions as products of single-particle orbitals. Resulting mean-field equations with a nonvanishing right-hand side turn out to be a generalization of the traditional Hartree or Hatree–Fock type equations. These TIMF equations are successfully solved numerically for the case of short-range forces. In this paper, we test the validity of this theory for the Coulomb interaction between two particles, that is, a long-range interaction. A numerical comparison between the exact and the mean-field solutions is conducted

PACS Nos.: 31.15.Ne, 31.15.Pf, 21.45.+v,25.10.-i
QCD corrections to heavy quark decays
Authors: Blokland I
Published: July 2007

The calculation of QCD corrections to heavy quark decay rates has progressed steadily in recent years. With the help of specialized techniques, symbolic computation, and a growing base of experience, a wide variety of special cases have been evaluated. These results have been applied to decays such as t → bW, b → s γ, b → u[Formula: see text]ν, and b → c[Formula: see text]ν.

PACS Nos.: 12.38.Bx, 13.30.Ce
Multisoliton configurations in Skyrme-like models
Authors: Longpré J -P , Marleau L
Published: July 2007

We explore the higher topological charge sector for generalized SU(2) Skyrme models in search of the static-field configuration with the lowest energy that would better reproduce what is expected for nuclei. Indeed the Skyrme model leads, for example, to toroidal, tetrahedral, and cubic symmetries for B = 2, 3, and 4 configurations, respectively, whereas nucleons in nuclei are presumably preserving their individuality. It turns out that the symmetries of the soliton solutions for the extended Skyrme models presented in this work are the same as for the Skyrme model at least for topological charges B < 5, which suggest that the Skyrme model has to be modified significantly to preserve the individual nature of the nucleons in nuclei.

PACS Nos.: 12.39.Dc, 10.11.Lm
Bose-Einstein condensates and thermal field theory
Authors: Kovalchuk E , Kobes R
Published: July 2007

We consider a homogeneous nonideal Bose gas in equilibrium at nonzero temperature below the critical temperature Tc in the framework of thermal field theory. Quantum corrections up to second order are calculated, which are shown to be crucial in obtaining the correct behavior in thermodynamic quantities such as the specific heat.

PACS Nos.: 67.40.–w, 11.10.Wx
Effective Hamiltonian theory and its applications in quantum information
Authors: James D F , Jerke J
Published: July 2007

This paper presents a useful compact formula for deriving an effective Hamiltonian describing the time-averaged dynamics of detuned quantum systems. The formalism also works for ensemble-averaged dynamics of stochastic systems. To illustrate the technique, we give examples involving Raman processes, Bloch-Siegert shifts, and quantum logic gates.

PACS Nos: 03.65.–w
Semiclassical position and momentum information entropy for sech2 and a family of rational potentials
Authors: Coffey M W
Published: July 2007

The classical and semiclassical position and momentum information entropies for the reflectionless sech2 potential and a family of rational potentials are obtained explicitly. The sum of these entropies is of interest for the entropic uncertainty principle that is stronger than the Heisenberg uncertainty relation. The analytic results relate the classical period of the motion, total energy, position and momentum entropy, and dependence upon the principal quantum number n. The logarithmic energy dependence of the entropies is presented. The potentials considered include as special cases the attractive delta function and square well.

PACS Nos.: 03.67–a, 03.65.Sq, 03.65.Ge, 03.65.–w
Problems with complex actions
Authors: Alexanian G , MacKenzie R , Paranjape M B , Ruel Jonathan
Published: July 2007

We consider Euclidean functional integrals involving actions that are not exclusively real. This situation arises, for example, when there are t-odd terms in the the Minkowski action. Writing the action in terms of only real fields (which is always possible), such terms appear as explicitly imaginary terms in the Euclidean action. The usual quanization procedure that involves finding the critical points of the action and then quantizing the spectrum of fluctuations about these critical points fails. In the case of complex actions, there do not exist, in general, any critical points of the action on the space of real fields, the critical points are in general complex. The proper definition of the function integral then requires the analytic continuation of the functional integration into the space of complex fields so as to pass through the complex critical points according to the method of steepest descent. We show a simple example where this procedure can be carried out explicitly. The procedure of finding the critical points of the real part of the action and quantizing the corresponding fluctuations, treating the (exponential of the) complex part of the action as a bounded integrable function is shown to fail in our explicit example, at least perturbatively.

PACS Nos.: 11.10.–z, 03.70.+k