bluuebunny/crossref_metadata_2025 huggingface dataset:
Linear least squares, the spreadsheet, and Filip
Authors: de Levie Robert
Published: June 2007

The numerical analysis of a NIST reference data set on a spreadsheet is illustrated in detail. We describe several interesting features, such as an efficient way of centering when fitting data to a high-order polynomial, and a little-known aspect of the imprecision of the imprecision. We also discuss a powerful alternative to standard matrix inversion, an extended set of add-in matrix functions for Excel, and software for making spreadsheet calculations with extended number length.
Hands-on gravitational wave astronomy: Extracting astrophysical information from simulated signals
Authors: Rubbo Louis J. , Larson Shane L. , Larson Michelle B. , Ingram Dale R.
Published: June 2007

In this article we introduce an activity in which introductory astronomy students act as gravitational wave astronomers by extracting information from simulated gravitational wave signals. The process mimics the way real gravitational wave analysis is handled by using plots of a pure gravitational wave signal. The students measure the properties of the simulated signal and use these measurements to evaluate standard relations for astrophysical source parameters. Although the activity described focuses on circular binaries, the techniques described can be applied to other gravitational wave sources as well. A problem based on the discussion in this paper is available for use in introductory laboratory courses.
Visualizing standing waves along the two parallel conducting pipes using household electronic appliances
Authors: Kim Seung Man , Kim Jung Bog
Published: June 2007

We describe an experiment designed to visualize an electromagnetic standing wave by using a video recorder as a source, two parallel conducting pipes as a transmitter, a small dipole antenna as a detector, and a computer with a TV card as a receiver. Students observe the periodic variation of the intensity on a computer or TV display while the dipole antenna scans along the two parallel conducting pipes. The measured wavelengths and computed phase velocities are plotted as a function of UHF carrier frequencies. Two contrasting patterns in short- and open-circuited terminations are consistent with predictions of field theory using appropriate boundary conditions.
Combinatorics and Boson normal ordering: A gentle introduction
Authors: Blasiak P. , Horzela A. , Penson K. A. , Solomon A. I. , Duchamp G. H. E.
Published: June 2007

We discuss a general combinatorial framework for operator ordering problems by applying it to the normal ordering of the powers and exponential of the boson number operator. The solution of the problem is given in terms of Bell and Stirling numbers enumerating partitions of a set. This framework reveals several inherent relations between ordering problems and combinatorial objects, and displays the analytical background to Wick’s theorem. The methodology can be straightforwardly generalized from the simple example we discuss to a wide class of operators.
Falling elastic bars and springs
Authors: Aguirregabiria J. M. , Hernández A. , Rivas M.
Published: June 2007

We analyze the initial motion of an elastic bar that is suddenly released after being hung from one end. The analytical solutions uncover some unexpected properties, which can be checked with a digital camera or camcorder in an alternative setup in which a spring is substituted for the bar. The model and the experiments are useful for understanding the similarities and differences between the elastic properties of bars and springs. Students can use the simple experiments to improve their understanding of elastic waves.
Can Maxwell’s equations be obtained from the continuity equation?
Authors: Heras José A.
Published: June 2007

We formulate an existence theorem that states that, given localized scalar and vector time-dependent sources satisfying the continuity equation, there exist two retarded fields that satisfy a set of four field equations. If the theorem is applied to the usual electromagnetic charge and current densities, the retarded fields are identified with the electric and magnetic fields and the associated field equations with Maxwell’s equations. This application of the theorem suggests that charge conservation can be considered to be the fundamental assumption underlying Maxwell’s equations.
New Guinea Pig Model of Cryptococcal Meningitis
Authors: Kirkpatrick William R. , Najvar Laura K. , Bocanegra Rosie , Patterson Thomas F. , Graybill John R.
Published: June 2007

We developed a guinea pig model of cryptococcal meningitis to evaluate antifungal agents. Immunosuppressed animals challenged intracranially with
Cryptococcus neoformans
responded to fluconazole and voriconazole. Disease was monitored by serial cerebrospinal fluid (CSF) cultures and quantitative organ cultures. Our model produces disseminating central nervous system disease and responds to antifungal therapy.
Large-Scale Surveillance of
Plasmodium falciparum crt
(
K76T
) in Northern Ghana
Authors: Ehrhardt Stephan , Eggelte Teunis A. , Kaiser Sarah , Adjei Lydia , Burchard Gerd D. , Anemana Sylvester D. , Bienzle Ulrich , Mockenhaupt Frank P.
Published: June 2007

Surveillance of
Plasmodium falciparum crt
(
K76T
) [Pf
crt
(
K76T
)], a resistance marker of chloroquine and, limitedly, amodiaquine, in >4,000 children in northern Ghana revealed a prevalence of 79%. Pf
crt
(
K76T
) was heterogeneously distributed and associated with chloroquine use, low parasitemia, and the dry season. Widespread chloroquine resistance challenges the regional life span of amodiaquine as a partner drug in artemisinin combination therapy.
Peroxide Bond-Dependent Antiplasmodial Specificity of Artemisinin and OZ277 (RBx11160)
Authors: Kaiser Marcel , Wittlin Sergio , Nehrbass-Stuedli Angela , Dong Yuxiang , Wang Xiaofang , Hemphill Andrew , Matile Hugues , Brun Reto , Vennerstrom Jonathan L.
Published: June 2007

Using nonperoxidic analogs of artemisinin and OZ277 (RBx11160), the strong in vitro antiplasmodial activities of the latter two compounds were shown to be peroxide bond dependent. In contrast, the weak activities of artemisinin and OZ277 against six other protozoan parasites were peroxide bond independent. These data support the iron-dependent artemisinin alkylation hypothesis.
Emergence of KPC-2 and KPC-3 in Carbapenem-Resistant
Klebsiella pneumoniae
Strains in an Israeli Hospital
Authors: Leavitt Azita , Navon-Venezia Shiri , Chmelnitsky Inna , Schwaber Mitchell J. , Carmeli Yehuda
Published: June 2007

Carbapenem resistance due to KPC has rarely been observed outside the United States. We noticed a sharp increase in carbapenem-resistant
Klebsiella pneumoniae
strains possessing KPC in Tel Aviv Medical Center from 2004 to 2006. Sixty percent of the isolates belonged to a single clone susceptible only to gentamicin and colistin and carried the
bla
KPC-3
gene, while almost all other clones carried the
bla
KPC-2
gene. This rapid dissemination of KPC outside the United States is worrisome.
Effect of Fluoroquinolone Treatment on Growth of and Toxin Production by Epidemic and Nonepidemic
Clostridium difficile
Strains in the Cecal Contents of Mice
Authors: Adams Daniel A. , Riggs Michelle M. , Donskey Curtis J.
Published: June 2007

Several recent outbreaks of
Clostridium difficile
-associated disease (CDAD) have been attributed to the emergence of an epidemic strain with increased resistance to fluoroquinolone antibiotics. Some clinical studies have suggested that fluoroquinolones with enhanced antianaerobic activity (i.e., gatifloxacin and moxifloxacin) may have a greater propensity to induce CDAD than ciprofloxacin and levofloxacin do. We examined the effects of subcutaneous fluoroquinolone treatment on in vitro growth of and toxin production by epidemic and nonepidemic
C. difficile
isolates in cecal contents of mice and evaluated the potential for these agents to inhibit fluoroquinolone-susceptible isolates during treatment. When
C. difficile
isolates were inoculated into cecal contents collected 2 days after the final antibiotic dose, gatifloxacin and moxifloxacin promoted significantly more growth and toxin production than ciprofloxacin and levofloxacin did. During treatment, gatifloxacin and moxifloxacin inhibited growth of fluoroquinolone-susceptible but not fluoroquinolone-resistant isolates. Ciprofloxacin and levofloxacin promoted growth of
C. difficile
when administered at higher doses (i.e., 20 times the human dose in mg/kg of body weight), and levofloxacin inhibited growth of fluoroquinolone-susceptible, but not fluoroquinolone-resistant,
C. difficile
isolates when administered in combination with ceftriaxone. Thus, fluoroquinolones with enhanced antianaerobic activity (i.e., gatifloxacin and moxifloxacin) promoted
C. difficile
growth to a greater extent than did ciprofloxacin and levofloxacin in this model. However, our findings suggest that fluoroquinolones may exert selective pressure favoring the emergence of epidemic fluoroquinolone-resistant
C. difficile
strains by inhibiting fluoroquinolone-susceptible but not fluoroquinolone-resistant isolates during treatment and that agents such as levofloxacin or ciprofloxacin can exert such selective pressure when administered in combination with antibiotics that disrupt the anaerobic microflora.
Helicobacter pyloriInfection Induces Oxidative Stress and Programmed Cell Death in Human Gastric Epithelial Cells
Authors: Ding Song-Ze , Minohara Yutaka , Fan Xue Jun , Wang Jide , Reyes Victor E. , Patel Janak , Dirden-Kramer Bernadette , Boldogh Istvan , Ernst Peter B. , Crowe Sheila E.
Published: June 2007

Helicobacter pyloriinfection is associated with altered gastric epithelial cell turnover. To evaluate the role of oxidative stress in cell death, gastric epithelial cells were exposed to various strains ofH. pylori, inflammatory cytokines, and hydrogen peroxide in the absence or presence of antioxidant agents. Increased intracellular reactive oxygen species (ROS) were detected using a redox-sensitive fluorescent dye, a cytochromecreduction assay, and measurements of glutathione. Apoptosis was evaluated by detecting DNA fragmentation and caspase activation. Infection withH. pylorior exposure of epithelial cells to hydrogen peroxide resulted in apoptosis and a dose-dependent increase in ROS generation that was enhanced by pretreatment with inflammatory cytokines. Basal levels of ROS were greater in epithelial cells isolated from gastric mucosal biopsy specimens fromH. pylori-infected subjects than in cells from uninfected individuals.H. pyloristrains bearing thecagpathogenicity island (PAI) induced higher levels of intracellular oxygen metabolites than isogeniccagPAI-deficient mutants.H. pyloriinfection and hydrogen peroxide exposure resulted in similar patterns of caspase 3 and 8 activation. Antioxidants inhibited both ROS generation and DNA fragmentation byH. pylori. These results indicate that bacterial factors and the host inflammatory response confer oxidative stress to the gastric epithelium duringH. pyloriinfection that may lead to apoptosis.
Relative Importance of T-Cell Subsets in Monocytotropic Ehrlichiosis: a Novel Effector Mechanism Involved inEhrlichia-Induced Immunopathology in Murine Ehrlichiosis
Authors: Ismail Nahed , Crossley Emily C. , Stevenson Heather L. , Walker David H.
Published: June 2007

Infection with gram-negative monocytotropicEhrlichiastrains results in a fatal toxic shock-like syndrome characterized by a decreased number ofEhrlichia-specific CD4+Th1 cells, the expansion of tumor necrosis factor alpha (TNF-α)-producing CD8+T cells, and the systemic overproduction of interleukin-10 (IL-10) and TNF-α. Here, we investigated the role of CD4+and CD8+T cells in immunity toEhrlichiaand the pathogenesis of fatal ehrlichiosis caused by infection with low- and high-dose (103and 105bacterial genomes/mouse, respectively) ehrlichial inocula. The CD4+T-cell-deficient mice showed exacerbated susceptibility to a lethal high- or low-dose infection and harbored higher bacterial numbers than did wild-type (WT) mice. Interestingly, the CD8+T-cell-deficient mice were resistant to a low dose but succumbed to a high dose ofEhrlichia. The absence of CD8+T cells abrogated TNF-α and IL-10 production, reduced tissue injury and bacterial burden, restored splenic CD4+T-cell numbers, and increased the frequency ofEhrlichia-specific CD4+Th1 cells in comparison to infected WT mice. Although fatal disease is perforin independent, our data suggested that perforin played a critical role in controlling bacterial burden and mediating liver injury. Similar to WT mice, mortality of infected perforin-deficient mice was associated with CD4+T-cell apoptosis and a high serum concentration of IL-10. Depletion of IL-10 restored the number of CD4+and CD8+T cells in infected WT mice. Our data demonstrate a novel mechanism of immunopathology in which CD8+T cells mediateEhrlichia-induced toxic shock, which is associated with IL-10 overproduction and CD4+T-cell apoptosis.
Pertussis Toxin Utilizes Proximal Components of the T-Cell Receptor Complex To Initiate Signal Transduction Events in T Cells
Authors: Schneider Olivia D. , Weiss Alison A. , Miller William E.
Published: June 2007

Pertussis toxin (PTx) is an AB5toxin produced by the human pathogenBordetella pertussis. Previous work demonstrates that the five binding (B) subunits of PTx can have profound effects on T lymphocytes independent of the enzymatic activity of the A subunit. Stimulation of T cells with holotoxin (PTx) or the B subunit alone (PTxB) rapidly induces signaling events resulting in inositol phosphate accumulation, Ca2+mobilization, interleukin-2 (IL-2) production, and mitogenic cell growth. Although previous reports suggest the presence of PTx signaling receptors expressed on T cells, to date, the receptor(s) and membrane proximal signaling events utilized by PTx remain unknown. Here we genetically and biochemically define the membrane proximal components utilized by PTx to initiate signal transduction in T cells. Using mutants of the Jurkat T-cell line deficient for key components of the T-cell receptor (TCR) pathway, we have compared stimulation with PTx to that of anti-CD3 monoclonal antibody (MAb), which directly interacts with and activates the TCR complex. Our genetic data in combination with biochemical analysis show that PTx (via the B subunit) activates TCR signaling similar to that of anti-CD3 MAb, including activation of key signaling intermediates such as Lck, ZAP-70, and phospholipase C-γ1. Moreover, the data indicate that costimulatory activity, as provided by CD28 ligation, is required for PTx to fully stimulate downstream indicators of T-cell activation such as IL-2 gene expression. By illuminating the signaling pathways that PTx activates in T cells, we provide a mechanistic understanding for how these signals deregulate immune system functions duringB. pertussisinfection.
Expression of the Programmed Death Ligand 1, B7-H1, on Gastric Epithelial Cells afterHelicobacter pyloriExposure Promotes Development of CD4+CD25+FoxP3+Regulatory T Cells
Authors: Beswick Ellen J. , Pinchuk Irina V. , Das Soumita , Powell Don W. , Reyes Victor E.
Published: June 2007

DuringHelicobacter pyloriinfection, T cells are recruited to the gastric mucosa, but the host T-cell response is not sufficient to clear the infection. Some of the recruited T cells respond in a polarized manner to a Th1 response, while others become anergic. We have previously shown that T-cell anergy may be induced during infection by the interaction of T cells with B7-H1, which is up-regulated on the gastric epithelium duringH. pyloriinfection. Recently, regulatory T (Treg) cells with a CD4+CD25highFoxP3+phenotype were found at an increased frequency in the gastric mucosa of biopsy specimens fromH. pylori-infected patients. While Treg cells are important in maintaining tolerance, they can also suppress immune responses during infection. In this study, we examined the induction of the Treg phenotype when naïve T cells were incubated with gastric epithelial cells exposed toH. pylori. The frequency of this phenotype was markedly decreased when B7-H1 was blocked with monoclonal antibodies or its expression was blocked with small interfering RNA. The functional role of these Treg cells was assessed in proliferation assays when the cells were cocultured with activated T cells, which effectively decreased proliferation of the cells.
l-Arginine Availability Regulates Inducible Nitric Oxide Synthase-Dependent Host Defense againstHelicobacter pylori
Authors: Chaturvedi Rupesh , Asim Mohammad , Lewis Nuruddeen D. , Algood Holly M. Scott , Cover Timothy L. , Kim Preston Y. , Wilson Keith T.
Published: June 2007

Helicobacter pyloriinfection of the stomach causes an active immune response that includes stimulation of inducible nitric oxide (NO) synthase (iNOS) expression. Although NO can killH. pylori, the bacterium persists indefinitely, suggesting that NO production is inadequate. We determined if the NO derived from iNOS in macrophages was dependent on the availability of its substrate,l-arginine (l-Arg). Production of NO byH. pylori-stimulated RAW 264.7 cells was dependent on thel-Arg concentration in the culture medium, and the 50% effective dose forl-Arg was 220 μM, which is above reported plasmal-Arg levels. While iNOS mRNA induction wasl-Arg independent, iNOS protein increased in anl-Arg-dependent manner that did not involve changes in iNOS protein degradation.l-Lysine, an inhibitor ofl-Arg uptake, attenuatedH. pylori-stimulated iNOS protein expression, translation, NO levels, and killing ofH. pylori. Whilel-Arg starvation suppressed global protein translation, at concentrations ofl-Arg at which iNOS protein was only minimally expressed in response toH. pylori, global translation was fully restored and eukaryotic translation initiation factor α was dephosphorylated.H. pylorilacking the generocF, which codes for a bacterial arginase, induced higher levels of NO production by increasing iNOS protein levels. When murine gastric macrophages were activated withH. pylori, supraphysiologic levels ofl-Arg were required to permit iNOS protein expression and NO production. These findings indicate thatl-Arg is rate limiting for iNOS translation and suggest that the levels ofl-Arg that occur in vivo do not permit sufficient NO generation by the host to killH. pylori.
Pseudomonas aeruginosa
Forms Biofilms in Acute Infection Independent of Cell-to-Cell Signaling
Authors: Schaber J. Andy , Triffo W. Jeffrey , Suh Sang Jin , Oliver Jeffrey W. , Hastert Mary Catherine , Griswold John A. , Auer Manfred , Hamood Abdul N. , Rumbaugh Kendra P.
Published: June 2007

Biofilms are bacterial communities residing within a polysaccharide matrix that are associated with persistence and antibiotic resistance in chronic infections. We show that the opportunistic pathogen
Pseudomonas aeruginosa
forms biofilms within 8 h of infection in thermally injured mice, demonstrating that biofilms contribute to bacterial colonization in acute infections as well. Using light, electron, and confocal scanning laser microscopy,
P. aeruginosa
biofilms were visualized within burned tissue surrounding blood vessels and adipose cells. Although quorum sensing (QS), a bacterial signaling mechanism, coordinates differentiation of biofilms in vitro, wild-type and QS-deficient
P. aeruginosa
strains formed similar biofilms in vivo. Our findings demonstrate that
P. aeruginosa
forms biofilms on specific host tissues independently of QS.
Coordinated Expression ofBorrelia burgdorferiComplement Regulator-Acquiring Surface Proteins during the Lyme Disease Spirochete's Mammal-Tick Infection Cycle
Authors: Bykowski Tomasz , Woodman Michael E. , Cooley Anne E. , Brissette Catherine A. , Brade Volker , Wallich Reinhard , Kraiczy Peter , Stevenson Brian
Published: June 2007

The Lyme disease spirochete,Borrelia burgdorferi, is largely resistant to being killed by its hosts’ alternative complement activation pathway. One possible resistance mechanism of these bacteria is to coat their surfaces with host complement regulators, such as factor H. Five differentB. burgdorferiouter surface proteins having affinities for factor H have been identified: complement regulator-acquiring surface protein 1 (BbCRASP-1), encoded bycspA; BbCRASP-2, encoded bycspZ; and three closely related proteins, BbCRASP-3, -4, and -5, encoded byerpP,erpC, anderpA, respectively. We now present analyses of the recently identified BbCRASP-2 andcspZexpression patterns throughout theB. burgdorferiinfectious cycle, plus novel analyses of BbCRASP-1 anderp-encoded BbCRASPs. Our results, combined with data from earlier studies, indicate that BbCRASP-2 is produced primarily during established mammalian infection, while BbCRASP-1 is produced during tick-to-mammal and mammal-to-tick transmission stages but not during established mammalian infection, and Erp-BbCRASPs are produced from the time of transmission from infected ticks into mammals until they are later acquired by other feeding ticks. Transcription ofcspZand synthesis of BbCRASP-2 were severely repressed during cultivation in laboratory medium relative to mRNA levels observed during mammalian infection, andcspZexpression was influenced by culture temperature and pH, observations which will assist identification of the mechanisms employed byB. burgdorferito control expression of this borrelial infection-associated protein.
Identification of Gene Products Involved in Biofilm Production by
Moraxella catarrhalis
ETSU-9 In Vitro
Authors: Pearson Melanie M. , Hansen Eric J.
Published: June 2007

Moraxella catarrhalis
ETSU-9 was subjected to random transposon insertion mutagenesis to identify genes encoding products involved in the ability of the organism to form biofilms in vitro. Screening of approximately 3,000 transposon insertion mutants in the crystal violet-based biofilm assay system yielded six mutants that exhibited greatly reduced abilities to form biofilms. Three of these mutants had transposon insertions in the
uspA2H
gene, which encodes a surface protein previously shown to be involved in the ability of
M. catarrhalis
to both attach to human cell lines in vitro and resist killing by normal human serum. Random insertion mutagenesis of the
uspA2H
gene, involving the introduction of a 15-nucleotide fragment encoding 5 amino acids, was used to attempt to identify the domain(s) necessary for biofilm formation. Most of these insertions adversely affected biofilm formation, whereas the abilities of these same mutants to attach to Chang conjunctival epithelial cells in vitro were usually not reduced. Gain-of-function experiments showed that introduction of the
M. catarrhalis
ETSU-9
uspA2H
gene into
Escherichia coli
conferred biofilm formation ability on this recombinant strain. Two of the other three
M. catarrhalis
ETSU-9 transposon insertion mutants that had greatly reduced abilities to form biofilms were shown to have insertions in genes encoding products predicted to be directly or indirectly involved in cell wall metabolism.
Upregulation of CCL20 and Recruitment of CCR6+Gastric Infiltrating Lymphocytes inHelicobacter pyloriGastritis
Authors: Wu Yi-Ying , Tsai Hwei-Fang , Lin We-Cheng , Hsu Ping-I , Shun Chia-Tung , Wu Ming-Shiang , Hsu Ping-Ning
Published: June 2007

Helicobacter pyloriinfection is associated with an inflammatory response in the gastric mucosa, leading to chronic gastritis, peptic ulcers, and gastric cancer. There is increased T-cell infiltration at the site of infection withH. pylori. CCR6, a specific β-chemokine receptor for CCL20 (MIP-3α/LARC/exodus), has recently been reported to mediate lymphocyte homeostasis and immune responses in mucosal tissue, and it may play a role in chemokine-mediated lymphocyte trafficking during gastric inflammation. In this study, we investigated the role of CCR6 and its ligand, CCL20, in inducing an inflammatory response in the gastric mucosa duringH. pyloriinfection. Gastric infiltrating T lymphocytes were isolated from endoscopic biopsy specimens ofH. pylorigastritis patients and analyzed for the expression of the CCR6 chemokine receptor. Our results demonstrated that there was significantly increased CCR6 expression in CD3+T cells infiltrating the gastric mucosa, and the CCR6 ligand, the CCL20 chemokine, was selectively expressed in inflamed gastric tissues. The production of CCL20 was upregulated in response toH. pyloriin gastric epithelial cells when there was stimulation by the proinflammatory cytokines interleukin-1β and tumor necrosis factor alpha. Furthermore, recombinant CCL20 induced lymphocyte chemotaxis migration in fresh gastric T cells ex vivo, indicating that the gastric T cells could migrate toward inflammatory sites via CCR6/CCL20 interaction. Our results suggest that the interaction between CCL20 and CCR6 may play a role in chemokine-mediated lymphocyte trafficking during gastric inflammation inHelicobacterinfection.
Acute patellofemoral pain: aggravating activities, clinical examination, MRI and ultrasound findings
Authors: Brushøj C , Hölmich P , Nielsen M B , Albrecht-Beste E
Published: June 2007

Objective:

To investigate acute anterior knee pain caused by overuse in terms of pain location, aggravating activities, findings on clinical examination and ultrasound/MRI examination. To determine if acute anterior knee pain caused by overuse should be classified as a subgroup of patellofemoral pain syndrome (PFPS).

Methods:

In a observational study design 30 army recruits with anterior knee pain (mean duration of pain 4 weeks) were examined using the PFPS pain severity scale (PSS), knee pain diagrams, standardised clinical examination, ultrasound and MRI examinations.

Results:

On PSS typical knee loading activities were the most painful, while sitting with knee bend for prolonged time caused surprisingly little pain. Pain was most commonly perceived in the peripatellar area (25 patients (83%)). The most common site of pain on clinical examination was the peripatellar area (25 patients (83%)), but other synovial covered structures including the fat pad of Hoffa (12 patients (40%)), the medial plica and the joint line (12 patients (40%)) were also involved. Only eight patients (27%) experienced pain on the patellofemoral compression test. Only discrete changes was detected on MRI/ultrasound.

Conclusions:

Acute anterior knee pain should be regarded as a subgroup of PFPS as both symptoms and clinical examination suggests this. The clinical examination with disseminated pain in all synovial covered structures is consistent with ideas of the importance of synovium in the genesis of pain.
High eccentric strength training reduces heart rate variability in healthy older men
Authors: Melo R C , Quitério R J , Takahashi A C M , Silva E , Martins L E B , Catai A M
Published: June 2007

Background:

Evaluation of non-pharmacological therapies that improve autonomic control of the heart rate in older subjects has a clinical significance, because reduced heart rate variability (HRV) can be associated with higher cardiovascular morbidity and mortality rates.

Objective:

To investigate if strength training improves cardiac autonomic control in healthy older men.

Methods:

The HRV of nine older healthy men (mean age 62 (2.0) years) was evaluated before and after 12 weeks of isokinetic eccentric strength training (2 days/week, 2–4 sets of 8–12 repetitions at 75–80% peak torque, involving knee flexion and extension. Electrocardiogram was continuously recorded for 15 min at rest, in supine and seated positions, before and after the strength training period. To estimate strength gains, the eccentric peak torque of the dominant leg was measured at 60°/s by the same isokinetic dynamometer.

Results:

Mean systolic blood pressure decreased (123.78 (8.3) to 117.67 (10.2) mmHg, p<0.05) and peak torque increased (extension 210.02 (38.5) to 252.71 (60.9) N.m; flexion: 117.56 (25.1) to 132.96 (27.3) N.m, p<0.05) after the strength training. The frequency domain indices showed a significant training effect (p<0.05), since low frequency in normalised units and low frequency/high frequency ratio increased (supine, 57 (14) to 68 (14), 1.56 (0.85) to 2.35 (1.48); seated, 65 (15) to 74 (8.0), 2.48 (1.09) to 3.19 (1.31), respectively), and high frequency in normalised units decreased (supine, 43 (14) to 32 (14); seated, 35 (15) to 26 (8)) after the training period.

Conclusion:

The results of the present investigation suggest that high eccentric strength training performed by healthy older men increases peak torque and reduces systolic blood pressure. However, an autonomic imbalance towards sympathetic modulation predominance was induced by an unknown mechanism.
Physical performance changes after unsupervised training during the autumn/spring semester break in competitive tennis players
Authors: Kovacs Mark S , Pritchett Robert , Wickwire P Jason , Green J Matthew , Bishop Phillip
Published: June 2007

Background:

All competitive tennis players take time away from coaches throughout the year; however, little information is available as to the short-term physiological effect of these breaks.

Objective:

The purpose of this investigation was to evaluate the impact of a 5 week off-campus structured, yet unsupervised, break from regular training in top collegiate tennis players.

Methods:

A nationally ranked collegiate NCAA Division I male tennis team (n = 8) performed a test battery in December and again in January after a 5 week period of recommended, yet unsupervised, training. The tests performed were 5, 10 and 20 m sprints, spider agility test, medicine ball power throws, standing long jump, Wingate anaerobic power test, VO2max, push-up and sit-up test, grip strength and range of motion (ROM) measures (goniometer) of the shoulder, hip, hamstring and quadriceps.

Results:

Paired t tests (p<0.05) showed significant decreases in mean (SEM) Wingate power measurements in Watts/kg (pre: 8.35 (0.19) w/kg ; post: 7.80 (0.24) w/kg ), minimum Wingate power (pre: 5.89 (0.27) w/kg; post: 5.10 (0.38) w/kg) and VO2maxvalues (pre: 53.90 (1.11) ml/kg/min; post: 47.86 (1.54) ml/kg/min). A significant increase was seen in the athlete’s fatigue index (pre: 44.26 (2.85)%; post: 51.41 (3.53)%), fastest 5 m (pre: 1.07 (0.03) s; post: 1.12 (0.02) s), 10 m (pre: 1.79 (0.03) s; post: 1.84 (0.04) s) and 20 m (pre: 3.07 (0.05) s; post: 3.13 (0.05) s) sprint times. No significant differences were seen for the other variables tested.

Conclusions:

These results suggest that a 5 week interruption of normal training can result in significant reductions in speed, power and aerobic capacity in competitive tennis players, likely owing to poor compliance with the prescribed training regimen. Therefore, coaches and trainers might benefit from techniques (eg, pre- and post-testing) requiring athletes’ to have accountability for unsupervised workouts.
Match activity and physiological responses during a junior female singles tennis tournament
Authors: Fernandez-Fernandez Jaime , Mendez-Villanueva Alberto , Fernandez-Garcia Benjamin , Terrados Nicolas
Published: June 2007

Objective:

To assess physiological load in conjunction with individual patterns of match-play activity in junior female tennis players during actual singles tennis competition.

Methods:

Eight elite junior female tennis players (n = 8; mean (SD) age, 17.3 (1.9) years) took part in a 2 day invitational tournament. Activity pattern analysis was performed during competitive matches. Heart rate and blood lactate concentrations were measured during selected changeovers breaks in play.

Results:

The activity profile of junior female players were: rally duration, (mean (SD)) 8.2 (5.2) s; rest time between rallies, 17.7 (6.5) s; effective playing time, 21.9 (3.8)%; strokes per rally, 2.7 (1.7); changes of direction per rally, 2.3 (1.4). The mean (SD) heart rate and blood lactate concentration recorded during the matches were 161 (5) beats/min and 2.0 (0.8) mmol/litre. Heart rate and blood lactate concentration values were influenced by the characteristics of the match and mean (SD) heart rate was significantly higher (p = 0.004) during service games (166 (15.4) beats/min) than in return games (156 (19.6) beats/min), while blood lactate concentrations were not significantly different (p = 0.83) between service (2.3 (0.6) mmol/litre) and return games (2.3 (0.9) mmol/litre). We found a significant (p<0.05) positive relationship between rally duration, strokes per rally, changes of direction and blood lactate and heart rate responses, with stronger correlations when the players were serving.

Conclusions:

The physiological (ie, blood lactate and heart rate) responses associated with match play were influenced by the characteristics of the match (rally duration, strokes per rally and changes of direction), with higher heart rate on service position. Training programs should reflect these demands placed on female players during competitive match play.
Core body temperature during competition in the heat: national boys’ 14s junior tennis championships
Authors: Bergeron Michael F , McLeod Kathryn S , Coyle John F
Published: June 2007

Objective:

To examine on-court core body temperature (TC) and sweat loss, as well as pre- and post-play hydration status, in elite adolescent tennis players during a national championships event in a hot climate.

Methods:

Eight healthy, fit, young male tennis players (mean (SD) age 13.9 (0.9) years; mass 56.0 (10.7) kg; height 169.2 (14.7) cm) were evaluated during first-round singles competition at the National Boys’ 14s Junior Championships in the heat (wet-bulb globe temperature (WBGT) 29.6 (0.4) °C). Five of those same players were also evaluated during a same-day doubles match (WBGT 31.3 (0.5) °C).

Results:

During doubles (4.37 (0.35) h after singles), pre-play urine specific gravity (USG) (1.025 (0.002); p = 0.06) and total sweat loss (1.9 (0.2) litres; p = 0.10) tended to be higher before and during doubles, respectively, compared to singles. However, percentage change in body mass (−0.5 (0.3) %) tended to be comparatively less (p = 0.08), even though the doubles matches were generally longer (106.6 (11.2) vs 78.8 (10.9) min; p = 0.09) and the degree minutes total was greater (p = 0.04). TCincreased (p<0.001) during singles and remained elevated, even after 10 min following the end of play. Notably, pre-play (singles) USG was strongly associated (p = 0.005) with the players’ final TC(38.7 (0.3) °C) recorded at the end of singles play.

Conclusion:

Junior tennis players who begin a match not well hydrated could have progressively increasing thermal strain and a greater risk for exertional heat illness as the match advances.
South African platinum mine employees reduce smoking in 5 years
Authors: Cheyip M Y N C K , Nelson G , Ross M H , Murray J
Published: June 2007

Background:South Africa adopted comprehensive tobacco control policies in the 1990s. Smoking has since declined in the general population, but there is little information on the effect of the campaign in labour-intensive industries, especially the mining industry where workers are exposed to dust, which may interact with tobacco smoke to cause respiratory disease.

Objectives:To determine the prevalence of, and trends in, smoking in employees of a South African platinum mining company, from 1998 to 2002, and to describe some demographic factors associated with their smoking habits.

Methods:This study used smoking data collected during annual fitness-to-work medical examinations. Employees were categorised into never, ever, continuous, new and ex-smokers. Data were analysed by race and age group. Age-standardised smoking prevalance rates were compared with rates in the South African general population.

Results:There were 80 713 records of 25 274 mine employees for the 5-year period. The decrease in smoking prevalence over this period was significant in both black and white men, but was greater in the former (from 42.9% to 29.8%, and from 47.2% to 44.7%, respectively). In 2002, the prevalence of smoking in black mine employees was 12.1% lower than that in black men in the general population. The prevalence of smoking decreased in black mine employees in all age groups (p<0.001); no such trend was seen for white mine employees. The proportion of light smokers increased significantly from 59.9% to 64.7%, with a corresponding significant decrease in the proportion of moderate and heavy smokers from 28.0% to 25.4%, and from 12.1% to 9.8%, respectively.

Conclusion:This study showed a significant decrease in smoking prevalence over a relatively short period, despite the fact that there was no smoking cessation programme in the company. The decline can be largely attributed to the South African government’s antismoking initiative and supports the drive to continue to increase excise taxes on cigarette products. Nevertheless, the relatively high prevalence of smoking in some groups of mine employees highlights the need for workplaces to support the government’s initiatives to curb smoking by establishing smoking cessation and prevention programmes.
Physician assessment of patient smoking in Indonesia: a public health priority
Authors: Ng Nawi , Prabandari Yayi Suryo , Padmawati Retna Siwi , Okah Felix , Haddock C Keith , Nichter Mark , Nichter Mimi , Muramoto Myra , Poston Walker S C , Pyle Sara A , Mahardinata Nurazid , Lando Harry A
Published: June 2007

Objective:To explore Indonesian physician’s smoking behaviours, their attitudes and clinical practices towards smoking cessation.

Design:Cross-sectional survey.

Setting:Physicians working in Jogjakarta Province, Indonesia, between October and December 2003.

Subjects:447 of 690 (65%) physicians with clinical responsibilities responded to the survey (236 men, 211 women), of which 15% were medical faculty, 35% residents and 50% community physicians.

Results:22% of male (n = 50) and 1% of female (n = 2) physicians were current smokers. Approximately 72% of physicians did not routinely ask about their patient’s smoking status. A majority of physicians (80%) believed that smoking up to 10 cigarettes a day was not harmful for health. The predictors for asking patients about smoking were being male, a non-smoker and a medical resident. The odds of advising patients to quit were significantly greater among physicians who perceived themselves as sufficiently trained in smoking cessation.

Conclusions:Lack of training in smoking cessation seems to be a major obstacle to physicians actively engaging in smoking cessation activities. Indonesian physicians need to be educated on the importance of routinely asking their patients about their tobacco use and offering practical advice on how to quit smoking.
Smoking, quitting and mortality in an elderly cohort of 56 000 Hong Kong Chinese
Authors: Lam Tai Hing , Li Zhi Bin , Ho Sai Yin , Chan Wai Man , Ho Kin Sang , Tham May Ked , Cowling Benjamin J , Schooling C Mary , Leung Gabriel M
Published: June 2007

Background:Although the harms of smoking are well established, it is unclear how they extend into old age in the Chinese.

Aim:To examine the relationship of smoking with all-cause and major cause-specific mortality in elderly Chinese men and women, respectively, in Hong Kong.

Methods:Mortality by smoking status was examined in a prospective cohort study of 56 167 (18 749 men, 37 416 women) Chinese aged ⩾65 years enrolled from 1998 to 2000 at all the 18 elderly health centres of the Hong Kong Government Department of Health.

Results:After a mean follow-up of 4.1 years, 1848 male and 2035 female deaths occured among 54 214 subjects (96.5% successful follow-up). At baseline, more men than women were current smokers (20.3% vs 4.0%) and former smokers (40.8% vs 7.9%). The adjusted RRs (95% CI) for all-cause mortality in former and current smokers, compared with never smokers, were 1.39 (1.23 to 1.56) and 1.75 (1.53 to 2.00) in men and 1.43 (1.25 to 1.64) and 1.38 (1.14 to 1.68) in women, respectively. For current smokers, the RRs (95% CI) for all-cause mortality were 1.59 (1.39 to 1.82), 1.72 (1.48 to 2.00) and 1.84 (1.43 to 2.35) for daily consumption of 1–9, 10–20 and >21 cigarettes, respectively (p for trend <0.001). RRs (95% CI) were 1.49 (1.30 to 1.72) and 2.20 (1.88 to 2.57) in former and current smokers for all deaths from cancer, and 1.24 (1.04 to 1.47) and 1.57 (1.28 to 1.94) for all cardiovascular deaths, respectively. Quitters had significantly lower risks of death than current smokers from all causes, lung cancer, all cancers, stroke and all cardiovascular diseases.

Conclusions:In old age, smoking continues to be a major cause of death, and quitting is beneficial. Smoking cessation is urgently needed in rapidly ageing populations in the East.
Changes in smoking prevalence in Ukraine in 2001–5
Authors: Andreeva Tatiana I , Krasovsky Konstantin S
Published: June 2007

Objectives:To analyse trends in smoking prevalence in Ukraine from three surveys conducted in 2001–5, and to explore correlates of observed changes, in order to estimate the stage of tobacco epidemic in Ukraine.

Design:Repeated national interview surveys in Ukraine in 2001, 2002 and 2005.

Main outcome measure:Prevalence of current smoking among the population aged ⩾15 years.

Results:The age-standardised prevalence of current smoking in Ukrainian men was 54.8% in 2001 and 66.8% in 2005. Among Ukrainian women, prevalence increased from 11.5% in 2001 to 20.0% in 2005. ORs for yearly increase in prevalence were estimated as 1.164 (95% CI 1.111 to 1.220) for men and 1.187 (1.124 to 1.253) for women, which implies that, on average, 3–4% of men and 1.5–2% of women living in Ukraine join the smoking population each year.

Conclusions:In Ukraine, smoking prevalence is increasing in most population groups. Among men, the medium deprivation group with secondary education has the highest smoking prevalence. Among women, while the most educated, young and those living in larger cities are the leading group for tobacco use, other groups are also increasing their tobacco use. Tobacco promotion efforts appear to have been significantly more effective in Ukraine than smoking control efforts. The decrease in real cigarette prices in Ukraine in 2001–5 could be the main factor explaining the recent growth in smoking prevalence.
A GALLERY OF CHUA ATTRACTORS: PART IV
Authors: BILOTTA ELEONORA , DI BLASI GIANPIERO , STRANGES FAUSTO , PANTANO PIETRO
Published: June 2007

The literature on Chua Oscillator includes more than a thousand papers, describing an astonishing variety of chaotic behavior. Gallery of Chua attractors, Part IV presents a collection of 101, previously unknown attractors, generated by a generalization of Chua circuit with a smooth nonlinear function. The gallery is the result of an extensive exploration of the parameter space for Chua cubic system, in which we used PCA and Hausdorf Distances to guide us. During this exploration we sensed the beauty of the chaotic patterns and recorded this beauty for the nonlinear community.

The attractors we describe here represent only a small proportion of those we discovered during our exploration of phase space: much intensive research remains to be done. However, the very number of attractors we found suggests it might be possible not only to detect the morphogenetic processes which determine the points in phase space ("catastrophe points") where a family of attractors disappears and another one comes to life, but to identify more general "laws of morphogenesis" governing the behavior of these systems. In this paper, we outline five such rules.
TIME-VARYING LINEARIZATION AND THE PERRON EFFECTS
Authors: LEONOV G. A. , KUZNETSOV N. V.
Published: June 2007

In the present survey, the contemporary state of the art of the problem of the justification of nonstationary linearizations is presented.
HORSESHOES NEAR HOMOCLINIC ORBITS FOR PIECEWISE LINEAR DIFFERENTIAL SYSTEMS IN ℝ3
Authors: LLIBRE JAUME , PONCE ENRIQUE , TERUEL ANTONIO E.
Published: June 2007

For a three-parametric family of continuous piecewise linear differential systems introduced by Arneodo et al. [1981] and considering a situation which is reminiscent of the Hopf-Zero bifurcation, an analytical proof on the existence of a two-parametric family of homoclinic orbits is provided. These homoclinic orbits exist both under Shil'nikov (0 < δ < 1) and non-Shil'nikov assumptions (δ ≥ 1). As it is well known for the case of differentiable systems, under Shil'nikov assumptions there exist infinitely many periodic orbits accumulating to the homoclinic loop. We also prove that this behavior persists at δ = 1. Moreover, for δ > 1 and sufficiently close to 1 we show that these periodic orbits persist but then they do not accumulate to the homoclinic orbit.
SENSITIVE PARAMETER DEPENDENCE OF AUTOCORRELATION FUNCTION IN PIECEWISE LINEAR MAPS
Authors: BARANOVSKI ALEXANDER L. , LAWRANCE ANTHONY J.
Published: June 2007

This paper is principally concerned with the effect of splitting and permuting, or shifting, the branches of an onto piecewise linear map, with particular regard to the effect on the autocorrelation of the associated chaotic sequence. This is shown to be a chaotic function of the shifting parameter of the map, and its sensitivity with respect to minute changes in this parameter is termed autocorrelation chaos. This paper presents both analytical and computational studies of the phenomenon.
CORRELATION AND SPECTRAL PROPERTIES OF MULTIDIMENSIONAL THUE–MORSE SEQUENCES
Authors: BARBÉ A. , VON HAESELER F.
Published: June 2007

This paper considers higher-dimensional generalizations of the classical one-dimensional two-automatic Thue–Morse sequence on ℕ. This is done by taking the same automaton-structure as in the one-dimensional case, but using binary number systems in ℤminstead of in ℕ. It is shown that the corresponding ±1-valued Thue–Morse sequences are either periodic or have a singular continuous spectrum, dependent on the binary number system. Specific results are given for dimensions up to six, with extensive illustrations for the one-, two- and three-dimensional case.
A COMPUTER-ASSISTED STUDY OF GLOBAL DYNAMIC TRANSITIONS FOR A NONINVERTIBLE SYSTEM
Authors: ADOMAITIS RAYMOND A. , KEVREKIDIS IOANNIS G. , DE LA LLAVE RAFAEL
Published: June 2007

We present a computer-assisted analysis of the phase space features and bifurcations of a noninvertible, discrete-time system. Our focus is on the role played by noninvertibility in generating disconnected basins of attraction and the breakup of invariant circle solutions. Transitions between basin of attraction structures are identified and organized according to "levels of complexity," a term we define in this paper. In particular, we present an algorithm that provides a computational approximation to the boundary (in phase space) separating points with different preimage behavior. The interplay between this boundary and other phase space features is shown to be crucial in understanding global bifurcations and transitions in the structure of the basin of attraction.
CELLULAR NEURAL NETWORKS FOR EDGE DETECTION
Authors: GRASSI GIUSEPPE , VECCHIO PIETRO , DI SCIASCIO EUGENIO , GRIECO LUIGI A.
Published: June 2007

This Letter presents an effective edge detection technique based on the cellular neural network paradigm. The approach exploits a rigorous model of the image contours and takes into account some electrical restrictions of existing hardware implementations. The method yields accurate results, better than the ones achievable by other cellular neural network-based techniques.