Search results for "HOF"

Different modes of activating phosphofructokinase, a key regulatory enzyme of glycolysis, in working vertebrate muscle

2002

Glycolytic flux in white muscle can be increased several-hundredfold by exercise. Phosphofructokinase (PFK; EC 2.7.1.11) is a key, regulatory enzyme of glycolysis, but how its activity in muscle is controlled is not fully, understood. In order not to neglect integrative aspects of metabolic regulation, we have studied in frogs (Rana temporaria) a physiological form of muscle work (swimming) that can be triggered like a reflex. We analysed swimming to fatigue in well rested frogs, recovery from exercise, and repeated exercise after 2 h of recovery. At various times, gastrocnemius muscles were tested for glycolytic intermediates and effectors of PFK. All metabolites responded similarly to the…

Neuromuscular function during drop jumps in young and elderly males

2011

The Hoffman reflex (H-reflex), indicating alpha-motoneuron pool activity, has been shown to be task - and in resting conditions - age dependent. How aging affects H-reflex activity during explosive movements is not clear at present. The purpose of this study was to examine the effects of aging on H-reflexes during drop jumps, and its possible role in drop jump performance. Ten young (26.8 ± 2.7 years) and twenty elderly (64.2 ± 2.7 years) subjects participated in the study. Maximal drop jump performance and soleus H-reflex response (H/M jump) 20 ms after ground contact were measured in a sledge ergometer. Maximal H-reflex, maximal M-wave, Hmax/Mmax-ratio and H-reflex excitability curves wer…

Diffraction by m-bonacci gratings

2015

We present a simple diffraction experiment with m-bonacci gratings as a new interesting generalization of the Fibonacci ones. Diffraction by these nonconventional structures is proposed as a motivational strategy to introduce students to basic research activities. The Fraunhofer diffraction patterns are obtained with the standard equipment present in most undergraduate physics labs and are compared with those obtained with regular periodic gratings. We show that m-bonacci gratings produce discrete Fraunhofer patterns characterized by a set of diffraction peaks which positions are related to the concept of a generalized golden mean. A very good agreement is obtained between experimental and …

First observation of a baryonic Bc+ decay

2014

A baryonic decay of the $B_c^+$ meson, $B_c^+\to J/\psi p\overline{p}\pi^+$, is observed for the first time, with a significance of $7.3$ standard deviations, in $pp$ collision data collected with the LHCb detector and corresponding to an integrated luminosity of $3.0$ fb$^{-1}$ taken at center-of-mass energies of $7$ and $8$ $\mathrm{TeV}$. With the $B_c^+\to J/\psi \pi^+$ decay as normalization channel, the ratio of branching fractions is measured to be \begin{equation*} \frac{\mathcal{B}(B_c^+\to J/\psi p\overline{p}\pi^+)}{\mathcal{B}(B_c^+\to J/\psi \pi^+)} = 0.143^{\,+\,0.039}_{\,-\,0.034}\,(\mathrm{stat})\pm0.013\,(\mathrm{syst}). \end{equation*} The mass of the $B_c^+$ meson is dete…

Zvaigžņotā Debess: 2008, Vasara

2008

Latvijas Zinātņu akadēmija, Latvijas Universitāte

Poincar é-Birkhoff fixed point theorem and periodic solutions of asymptotically linear planar Hamiltonian systems. (Turin Fortnight Lectures on Nonli…

2002

Willem Boshoff, artist's monograph and catalogue

2013

Willem Boshoff’s work articulates around a pivotal date, April 1994, the first democratic elections in South Africa. He may choose to work gigantic rocks of granite or establish vast installations of accumulated material. The artist claims that his work is based on language, often taking the form of Dictionaries. While reviewing the main questions by artists of the twentieth century, texts or artworks from Europe are systematically tested against their South African counterpart. Boshoff’s attitude is determined by a melancholic questioning of his role as a creator linked to a political situation and cultural milieu. He discovers more dynamic ways of presenting gestures when his artistic act…

Non-Conventional Tunable Spatial Filtering

1987

A virtual display of the Fraunhofer diffraction pattern of any object is formed in the transverse source plane by theyirtual diffracted rays extqn0ing in the region to the left of the screen containing the transparencyl),2). Except for a few cases '')"°), the concept of virtual Fourier transform appears not to have been made use of. The main idea of this paper is, bearing in mind the property referred to in the above paragraph, to describe a novel spatial filtering technique. In this way, one can obtain different filtered images, by simply moving the point source along the optical axis. The basic theory is described below.

Zvaigžņotā Debess: 2012/13, Ziema (218)

2012

Saturs: Dienas kārtībā – «melnie caurumi» ; «Pioneer-10» dodas uz Jupiteru ; A.Alksnis. Dīvains miglājs, kam daudz nosaukumu ; M.Ņečajeva, I.Šmelds. Jonosfēras pētījumi Ventspils Starptautiskajā radioastronomijas centrā ; L.Gulbe. Satelīts ne tikai televīzijai, bet arī mežu uzraudzībai ; I.Ķešāns. Nīls Ārmstrongs ; Pirmo reizi “ZvD”: Ints Ķešāns ; E.Bervalds. Par Jāņa Ikaunieka iecerēm un VSRC (nobeigums) ; J.Dambītis, A.Cibulis. Ievērojamais Latvijas matemātiķis Arvīds Lūsis (1900–1969) ; A.Alksnis. LVU astronomijas specialitātes studenti – 1952. gada diplomandi (3.turpin.) ; I.D., I.P. Šoziem atceramies: Arturs Balklavs-Grīnhofs (2.I 1933.) – 80, Ernests Grasbergs (8.III 1938.) – 75 ; K.Š…

Regulatory properties of 6-phosphofructokinase and control of glycolysis in boar spermatozoa.

2007

Glycolysis is crucial for sperm functions (motility and fertilization), but how this pathway is regulated in spermatozoa is not clear. This prompted to study the location and the regulatory properties of 6-phosphofructokinase (PFK, EC 2.7.1.11), the most important element for control of glycolytic flux. Unlike some other glycolytic enzymes, PFK showed no tight binding to sperm structures. It could readily be extracted from ejaculated boar spermatozoa by sonication and was then chromatographically purified. At physiological pH, the enzyme was allosterically inhibited by near-physiological concentrations of its co-substrate ATP, which induced co-operativity, i.e. reduced the affinity for the …