Biomedical subjects

S Funk

Publications and source records attributed to S Funk.

At least 19 recordsLinked to original sources

PubMed2006

HESS observations of the galactic center region and their possible dark matter interpretation.

The detection of gamma rays from the source HESS J1745-290 in the Galactic Center (GC) region with the High Energy Spectroscopic System (HESS) array of Cherenkov telescopes in 2004 is presented. After subtraction of the diffuse gamma-ray emission from the GC ridge, the source is compatible with a point source with spatial extent less than 1.2;{'}(stat) (95% C.L.). The measured energy spectrum above 160 GeV is compatible with a power law with photon index of 2.25+/-0.04(stat)+/-0.10(syst) and no significant flux variation is detected. It is finally found that the bulk of the very high energy emission must have non-dark-matter origin.

Journal Article↗

PubMed2006

Fast variability of tera-electron volt gamma rays from the radio galaxy M87.

The detection of fast variations of the tera-electron volt (TeV) (10(12) eV) gamma-ray flux, on time scales of days, from the nearby radio galaxy M87 is reported. These variations are about 10 times as fast as those observed in any other wave band and imply a very compact emission region with a dimension similar to the Schwarzschild radius of the central black hole. We thus can exclude several other sites and processes of the gamma-ray production. The observations confirm that TeV gamma rays are emitted by extragalactic sources other than blazars, where jets are not relativistically beamed toward the observer.

Journal Article↗

PubMed2006

Adsorption of CO2 on oxidized, defected, hydrogen and oxygen covered rutile (1 x 1)-TiO2(110).

Presented are initial, S(0) and coverage, Theta, dependent S(Theta), adsorption probability measurements of CO(2) as a function of impact energy, E(i) = 0.12-1.3 eV, adsorption temperature, T(s) = 85-300 K, hydrogen and oxygen pre-exposure, as well as density of defects, Gamma, as varied by annealing (T = 600-900 K) and Ar(+) ion sputtering (dose chi(Ar) at 600 eV at 85 K) of a rutile (1 x 1) TiO(2)(110) surface. The defect densities were qualitatively characterized by thermal desorption spectroscopy (TDS) of CO(2). The CO(2) TDS curves consisted of two structures that can be assigned to adsorption on pristine and oxygen vacancy sites, in agreement with earlier studies. S(0) decreased linearly with E(i) and was independent of T(s). The adsorption dynamics were dominated by the effect of precursor states leading to Kisliuk-like shapes over the E(i) and T(s) range studied. Oxygen vacancy sites reduced S(0) of CO(2). Preadsorbed oxygen blocked preferentially defect sites, which led to an increase in S(0). Hydrogen preadsorption results in physical site blocking with decreased S(0) as H-preexposure increased, while the shape of S(Theta) curves was conserved. In contrast to oxygen, hydrogen does not adsorb preferentially on defect sites. The adsorption probability data were parameterized by analytic functions (Kisliuk model) and by Monte Carlo simulations (MCSs).

Adsorption↗

PubMed2006

A low level of extragalactic background light as revealed by gamma-rays from blazars.

The diffuse extragalactic background light consists of the sum of the starlight emitted by galaxies through the history of the Universe, and it could also have an important contribution from the 'first stars', which may have formed before galaxy formation began. Direct measurements are difficult and not yet conclusive, owing to the large uncertainties caused by the bright foreground emission associated with zodiacal light. An alternative approach is to study the absorption features imprinted on the gamma-ray spectra of distant extragalactic objects by interactions of those photons with the background light photons. Here we report the discovery of gamma-ray emission from the blazars H 2356 - 309 and 1ES 1101 - 232, at redshifts z = 0.165 and z = 0.186, respectively. Their unexpectedly hard spectra provide an upper limit on the background light at optical/near-infrared wavelengths that appears to be very close to the lower limit given by the integrated light of resolved galaxies. The background flux at these wavelengths accordingly seems to be strongly dominated by the direct starlight from galaxies, thus excluding a large contribution from other sources-in particular from the first stars formed. This result also indicates that intergalactic space is more transparent to gamma-rays than previously thought.

Journal Article↗

PubMed2006

Discovery of very-high-energy gamma-rays from the Galactic Centre ridge.

The source of Galactic cosmic rays (with energies up to 10(15) eV) remains unclear, although it is widely believed that they originate in the shock waves of expanding supernova remnants. At present the best way to investigate their acceleration and propagation is by observing the gamma-rays produced when cosmic rays interact with interstellar gas. Here we report observations of an extended region of very-high-energy (> 10(11) eV) gamma-ray emission correlated spatially with a complex of giant molecular clouds in the central 200 parsecs of the Milky Way. The hardness of the gamma-ray spectrum and the conditions in those molecular clouds indicate that the cosmic rays giving rise to the gamma-rays are likely to be protons and nuclei rather than electrons. The energy associated with the cosmic rays could have come from a single supernova explosion around 10(4) years ago.

Journal Article↗

PubMed2006

Recent developments in clinimetric instruments.

Assessment of impairment and function is essential in order to monitor joint status and evaluate therapeutic interventions in patients with haemophilia. The improvements in the treatment of haemophilia have required the development of more sensitive tools to detect the more minor dysfunctions that may now be apparent. This paper outlines some of the recent developments in this field. The Haemophilia Joint Health Score (HJHS) provides a systematic and robust measure of joint impairment. The MRI Scoring System has been designed to provide a comprehensive scoring system combining both progressive and additive scales. The Functional Independence Score for Haemophilia (FISH) has been developed to assess performance of functional activities and can be used in conjunction with the Haemophilia Activities List (HAL) which provides a self report measure of function. It is recommended that both measures are evaluated as these tools measure different constructs. Further refinement and testing of the psychometric properties of all of these tools is in progress. More widespread use of these tools will enable the sharing of data across the world so promoting best practice and ultimately enhancing patient care.

Activities of Daily Living↗

PubMed2006

Hemophilia joint health score reliability study.

UNLABELLED: Measurement of joint health is critically important when assessing children with haemophilia. Few measures exist; they lack sensitivity to small changes, don't account for normal development and were never formally validated. To address these concerns, the Hemophilia Joint Health Score (HJHS) was developed by modifying existing scores. OBJECTIVE: To test the inter-observer and test-retest reliability of the HJHS. METHODS: Using a fully factorial design, four physiotherapists (from Canada, the United States and Sweden) examined eight boys with severe haemophilia A on two consecutive days using the HJHS. The boys ranged in age from 4-12 years and presented with variable joint damage. Six index joints (elbows, knees and ankles) were assessed on 11 impairment items including swelling, flexion and extension loss and gait. Concordance was measured by the intra-class correlation co-efficient. RESULTS: Reliability of the HJHS was excellent with an inter-observer co-efficient of 0.83 and a test-retest of 0.89. CONCLUSION: This study is the first in a series to assess the psychometric properties of the HJHS, a promising new measure of joint health in boys with haemophilia.

Ankle Joint↗

PubMed2005

Adsorption dynamics of CO2 on copper-precovered ZnO(0001)-Zn: a molecular-beam scattering and thermal-desorption spectroscopy study.

Initial, S(0), as well as coverage-dependent adsorption probability measurements, S(Theta), have been conducted at normal impact angle and as a function of the impact energy of CO(2), E(i), adsorption temperature, T(s), and copper precoverage, Theta(Cu) (at 300 K). S(0), which decreased from approximately 0.4 exponentially to approximately 0.05 with E(i) was independent of Theta(Cu). Astonishingly, S(0) for Cu on ZnO(0001)-Zn is smaller than for the clean support which indicates a chemical modification of the support by the Cu deposits. S(Theta) curves consist of two regimes, a Kisliuk-type and Langmuirian-type section. The first is consistent with capture zone models; the second may indicate direct adsorption of CO(2) on the Cu cluster. The thermal-desorption (TDS) curves for Cu on ZnO(0001)-Zn consist of two structures with binding energies of 26 and approximately 40 kJmol (nu=1 x 10(13) ls). The TDS results indicate that CO(2) populates predominantly the Cu deposits and the rim along the Cu nanoparticles. No indications for CO(2) dissociation could be obtained with Auger electron spectroscopy.

Journal Article↗

PubMed2005

Discovery of very high energy gamma rays associated with an x-ray binary.

X-ray binaries are composed of a normal star in orbit around a neutron star or stellar-mass black hole. Radio and x-ray observations have led to the presumption that some x-ray binaries called microquasars behave as scaled-down active galactic nuclei. Microquasars have resolved radio emission that is thought to arise from a relativistic outflow akin to active galactic nuclei jets, in which particles can be accelerated to large energies. Very high energy gamma-rays produced by the interactions of these particles have been observed from several active galactic nuclei. Using the High Energy Stereoscopic System, we find evidence for gamma-ray emission of >100 gigaelectron volts from a candidate microquasar, LS 5039, showing that particles are also accelerated to very high energies in these systems.

Journal Article↗

PubMed2005

A new population of very high energy gamma-ray sources in the Milky Way.

Very high energy gamma-rays probe the long-standing mystery of the origin of cosmic rays. Produced in the interactions of accelerated particles in astrophysical objects, they can be used to image cosmic particle accelerators. A first sensitive survey of the inner part of the Milky Way with the High Energy Stereoscopic System (HESS) reveals a population of eight previously unknown firmly detected sources of very high energy gamma-rays. At least two have no known radio or x-ray counterpart and may be representative of a new class of "dark" nucleonic cosmic ray sources.

Journal Article↗

PubMed2005

Enhanced angiogenesis characteristic of SPARC-null mice disappears with age.

The impairment of angiogenesis in aging has been attributed, in part, to alterations in proteins associated with the extracellular matrix (ECM). SPARC (secreted protein acidic and rich in cysteine/osteonectin/BM-40) is a matricellular protein that regulates endothelial cell function as well as cell-ECM interactions. We have previously shown that angiogenesis, as reflected by fibrovascular invasion into subcutaneously implanted polyvinyl alcohol (PVA) sponges, is increased in SPARC-null mice (6-9 months of age) relative to their wild-type (WT) counterparts. In this study, we define the influence of aging on (a) the expression of SPARC and (b) fibrovascular invasion into sponge implants in SPARC-null and WT mice. The expression of SPARC in fibroblasts and endothelial cells derived from young donors (humans mean age less than 30 years and mice 4-6 months of age) and old donors (humans mean age over 65 years and mice 22-27 months of age) decreased 1.6 to 2.3-fold with age. Analysis of fibrovascular invasion into sponges implanted into old (22-27 months) SPARC-null and WT mice showed no differences in percent area of invasion or collagenous ECM. Moreover, sponges from old SPARC-null and WT mice contained similar levels of VEGF that were significantly lower than those from young (4-6 months) mice. In contrast to fibroblasts from young SPARC-null mice, dermal fibroblasts from old SPARC-null mice did not migrate farther, proliferate faster, or produce greater amounts of VEGF relative to their old WT counterparts. However, when stimulated with TGF-beta1, primary cells isolated from the sponge implants, and dermal fibroblasts from both old SPARC-null and WT mice, showed marked increases in VEGF secretion. These data indicate that aging results in a loss of enhanced angiogenesis in SPARC-null mice, as a result of the detrimental impact of age on cellular functions, collagen deposition, and VEGF synthesis. However, the influence of aging on these processes may be reversed, in part, by growth factor stimulation.

Adult↗

PubMed2004

High-energy particle acceleration in the shell of a supernova remnant.

A significant fraction of the energy density of the interstellar medium is in the form of high-energy charged particles (cosmic rays). The origin of these particles remains uncertain. Although it is generally accepted that the only sources capable of supplying the energy required to accelerate the bulk of Galactic cosmic rays are supernova explosions, and even though the mechanism of particle acceleration in expanding supernova remnant (SNR) shocks is thought to be well understood theoretically, unequivocal evidence for the production of high-energy particles in supernova shells has proven remarkably hard to find. Here we report on observations of the SNR RX J1713.7 - 3946 (G347.3 - 0.5), which was discovered by ROSAT in the X-ray spectrum and later claimed as a source of high-energy gamma-rays of TeV energies (1 TeV = 10(12) eV). We present a TeV gamma-ray image of the SNR: the spatially resolved remnant has a shell morphology similar to that seen in X-rays, which demonstrates that very-high-energy particles are accelerated there. The energy spectrum indicates efficient acceleration of charged particles to energies beyond 100 TeV, consistent with current ideas of particle acceleration in young SNR shocks.

Journal Article↗

PubMed2004

Physical therapy and imaging outcome measures in a haemophilia population treated with factor prophylaxis: current status and future directions.

Routine infusions of factor VIII to prevent bleeding, known as prophylaxis, and other intensive therapies are being more broadly applied to patients with haemophilia. These therapies differ widely in replacement product usage, cost, frequency of venous access and parental effort. In order to address residual issues relating to recommendations, implementation, and evaluations of prophylaxis therapy in persons with haemophila, a multinational working group was formed and called the International Prophylaxis Study Group (IPSG). The group was comprised of haemophilia treaters actively involved in studies of prophylaxis from North America and Europe. Two expert committees, the Physical Therapy (PT) Working Group and the Magnetic Resonance Imaging (MRI) Working Group were organized to critically assess existing tools for assessment of joint outcome. These two committees independently concluded that the WFH Physical Examination Scale (WFH PE Scale) and the WFH X-ray Scale (WFH XR Scale) were inadequately sensitive to detect early changes in joints. New scales were developed based on suggested modifications of the existing scales and called the Haemophilia Joint Health Score (HJHS) and the International MRI Scales. The new scales were piloted. Concordance was measured by the intra-class correlation coefficient of variation. Reliability of the HJHS was excellent with an inter-observer co-efficient of 0.83 and a test-retest value of 0.89. The MRI study was conducted using both Denver and European scoring approaches; inter-reader reliability using the two approaches was 0.88 and 0.87; test-retest reliability was 0.92 and 0.93. These new PT and MRI scales promise to improve outcome assessment in children on early preventive treatment regimens.

Hemophilia A↗

PubMed2002

Estradiol absorption from vaginal tablets in postmenopausal women.

OBJECTIVE: To evaluate absorption of estradiol (E2) and compare two low doses of 17 beta-E2 (25 microgram and 10 microgram) in postmenopausal women with atrophic vaginitis. METHODS: In a double-masked, randomized, parallel-group study, 58 postmenopausal women were treated with 25 microgram or 10 microgram of 17 beta-E2 for 12 weeks. We report data for 42 eligible subjects who had serum E2 concentrations below 20 pg/mL at baseline and complete data available at the baseline visit (30 minutes before tablet insertion) and weeks 2 and 12. Serum E2 and FSH concentrations were measured at specified intervals. The area under the curve, maximal concentration, and time to maximal concentration were measured for serum E2 concentrations. Maturation values of vaginal epithelial cells were assessed as indicators of change in vaginal epithelium condition in response to treatment. RESULTS: After 12 weeks of treatment, the area under the curve, maximal and average over 24-hour E2 concentration were higher in the 25-microgram (563 pg. hour/mL, 49 and 23 pg/mL) than in the 10-microgram (264 pg. hour/mL, 22 and 11 pg/mL) group. Seventy-four percent in the 25-microgram and 96% in the 10-microgram groups had low systemic absorption of E2, that is, area under the curve (0-24 hour) less than 500 pg/mL. All but three women who received 25 microgram had mean FSH levels below 35 mIU/mL. CONCLUSION: Treatment with 25 or 10 microgram of 17 beta-E2 vaginal tablets resulted in low absorption of estrogen without systemic effects often associated with hormone replacement therapy. After 12 weeks of therapy for atrophic vaginitis, absorption patterns remained consistent, and women did not have accumulations of circulating E2.

Absorption↗

PubMed2002

[Obstructive jaundice and acute pancreatitis due to an obstruction of the afferent loop after billroth-II-resection].

An obstruction of the afferent loop after Billroth-II-resection is an extremely rare late complication of this procedure. We report on a 76-year-old female patient with a history of Billroth-II-resection 11 years ago who was admitted due to acute pancreatitis and obstructive jaundice. Abdominal sonography lead to the suspicion of a dilated afferent loop, which could be proven by means of magnetic resonance imaging. A tumorous lesion as cause of the obstructive jaundice was not detectable. Intraoperatively a volvulus of the small intestine and strangling adhesions near the Braun's anastomosis were seen, causing the obstruction of the afferent loop. Following reposition of the small intestine and adhesiolysis the patient gained a quick relief of symptoms and the jaundice disappeared completely.

Acute Disease↗

PubMed2000

Femtosecond surface vibrational spectroscopy of CO adsorbed on Ru(001) during desorption

Using time-resolved sum-frequency generation spectroscopy, the C- O stretch vibration of carbon monoxide adsorbed on a single-crystal Ru(001) surface is investigated during femtosecond near-IR laser excitation leading to desorption. A large transient redshift, a broadening of the resonance, and a strong decrease in intensity are observed. These originate from coupling of the C- O stretch to low-frequency modes, especially the frustrated rotation, that are highly excited in the desorption process.

Journal Article↗

PubMed2000

Joint evaluation instruments for children and adults with haemophilia.

With the heightened interest in protocols to prevent or treat complications of haemophilia related to recurrent haemarthroses, there is a need for sensitive joint-evaluation tools. The World Federation of Haemophilia (WFH) Physical Joint Examination instrument, which was developed for persons with haemophilia worldwide, is not sensitive enough to detect early structural or functional abnormalities. Therefore, we have expanded the WFH instrument to detect more subtle abnormalities of joint structure and function, and in addition, developed a new scale specifically tailored to the dynamic growth and gait development of children. We compared the original and three new instruments in 43 children with haemophilia. The three new scales all showed better correlation with the WFH pain instrument than did the original WFH physical examination instrument (P < 0.01 for each of the new instruments vs. P > 0.05 for the WFH instrument). In addition, results of the new child physical examination instrument best conformed to a normal distribution (P=0.35) and this instrument had better overall statistical performance. This instrument should be studied further in prospective, longitudinal clinical trials of young children.

Adolescent↗

PubMed1999

Phonon- versus electron-mediated desorption and oxidation of CO on Ru(0001)

Heating of a ruthenium surface on which carbon monoxide and atomic oxygen are coadsorbed leads exclusively to desorption of carbon monoxide. In contrast, excitation with femtosecond infrared laser pulses enables also the formation of carbon dioxide. The desorption is caused by coupling of the adsorbate to the phonon bath of the ruthenium substrate, whereas the oxidation reaction is initiated by hot substrate electrons, as evidenced by the observed subpicosecond reaction dynamics and density functional calculations. The presence of this laser-induced reaction pathway allows elucidation of the microscopic mechanism and the dynamics of the carbon monoxide oxidation reaction.

Journal Article↗