1,138 research outputs found
On Conserved Current in Markovian Open Quantum Systems
We reexamine the markovian approximation of local current in open quantum
systems, discussed recently by Gebauer and Car. Our derivation is more
transparent, the proof of current conservation becomes explicit and easy.Comment: 3 page
Subacute exposure of rats by metal oxide nanoparticles through the airways: general toxicity and neuro-functional effects
In order to create an animal model of human inhalational exposure by industrial trAct
metal fumes, nanoparticulate metal oxides (MnO2
, CdO2
, PbO) were synthesized and instilled
into the trachea of rats 5 times a week for 6 weeks (metal doses per kg b.w.: 2.63 and 5.26 mg
Mn; 0.04 and 0.4 mg Cd; 2 and 4 mg Pb). At the end, the rats’ body weight gain during the treatment was determined, the animals had an open field session to investigate their spontaneous
motility, and finally spontaneous and stimulus-evoked cortical activity was recorded in urethane
anaesthesia. Mn caused decrease of open field ambulation and rearing, Cd had no effect,
whereas Pb caused decreased rearing and increased ambulation. Spontaneous cortical activity
was shifted to higher frequencies with each metal. Cortical evoked potentials had lengthened
latency, mainly with Mn and Cd; and increased frequency dependence with Cd and Pb but hardly
with Mn. The effects proved indirectly that the metal content of the nanoparticles had access
form the airways to the CNS. Our method seems suitable for modelling human nervous system
damage due to inhaled nanoparticles
Effect of particle size on the surface properties and morphology of ground flax
Flax fibers were ground with a ball-mill and four fractions with different size ranges were collected by sieving. These were tested for water sorption, degree of polymerization (DP), copper number, hydroxyl number and analyzed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and inverse gas chromatography (IGC). Significant differences were found between the properties of the flax fiber and those of the ground versions, including fragmentation of fibers, increase of water sorption, copper number, hydroxyl number and surface O/C ratio, and decrease of DP, crystallite size and dispersive component of surface energy (gammasd). Some parameters depended on the particle size: O/C ratio and hydroxyl number had local maxima at 315-630 ÎĽm, while gammasd increased steadily with the decrease of particle size. These relationships were explained by fiber disintegration, destruction of waxy surface layer, exposure of cellulosic components, increase of surface area and crystalline imperfections
A fás vegetáciĂł jellegzetessĂ©gei az AlsĂł-hegy (Gömör–Tornai-karszt) karsztfennsĂkján
Observation of thermally-induced magnetic relaxation in a magnetite grain using off-axis electron holography
A synthetic basalt comprising magnetic Fe3O4 grains (~ 50 nm to ~ 500 nm in diameter) is
investigated using a range of complementary nano-characterisation techniques. Off-axis electron
holography combined with in situ heating allowed for the visualisation of the thermally-induced
magnetic relaxation of an Fe3O4 grain (~ 300 nm) from an irregular domain state into a vortex state at
550ËšC, just below its Curie temperature, with the magnetic intensity of the vortex increasing on cooling
Functional modulation of the transient outward current Ito by KCNE beta-subunits and regional distribution in human non-failing and failing hearts
Objectives: The function of Kv4.3 (KCND3) channels, which underlie the transient outward current I,, in human heart, can be modulated by several accessory subunits such as KChIP2 and KCNE1-KCNE5. Here we aimed to determine the regional expression of Kv4.3, KChIP2, and KCNE mRNAs in non-failing and failing human hearts and to investigate the functional consequences of subunit coexpression in heterologous expression systems.
Methods: We quantified mRNA levels for two Kv4.3 isoforms, Kv4.3-S and Kv4.3-L, and for KChIP2 as well as KCNE1-KCNE5 with real-time RT-PCR. We also studied the effects of KCNEs on Kv4.3 + KChIP2 current characteristics in CHO cells with the whole-cell voltage-clamp method.
Results: In non-failing hearts, low expression was found for KCNE1, KCNE3, and KCNE5, three times higher expression for KCNE2, and 60 times higher for KCNE4. Transmural gradients were detected only for KChIP2 in left and right ventricles. Compared to non-failing tissue, failing hearts showed higher expression of Kv4.3-L and KCNE1 and lower of Kv4.3-S, KChIP2, KCNE4, and KCNE5. In CHO cells, Kv4.3 + KChIP2 currents were differentially modified by co-expressed KCNEs: time constants of inactivation were shorter with KCNE1 and KCNE3-5 while time-to-peak was decreased, and V-0.5 of steady-state inactivation was shifted to more negative potentials by all KCNE subunits. Importantly, KCNE2 induced a unique and prominent 'overshoot' of peak current during recovery from inactivation similar to that described for human I-to while other KCNE subunits induced little (KCNE4,5) or no overshoot.
Conclusions: All KCNEs are expressed in the human heart at the transcript level. Compared to It. in native human myocytes, none of the combination of KChIP2 and KCNE produced an ideal congruency in current characteristics, suggesting that additional factors contribute to the regulation of the native I-to channel
A Linear Iterative Unfolding Method
A frequently faced task in experimental physics is to measure the probability
distribution of some quantity. Often this quantity to be measured is smeared by
a non-ideal detector response or by some physical process. The procedure of
removing this smearing effect from the measured distribution is called
unfolding, and is a delicate problem in signal processing, due to the
well-known numerical ill behavior of this task. Various methods were invented
which, given some assumptions on the initial probability distribution, try to
regularize the unfolding problem. Most of these methods definitely introduce
bias into the estimate of the initial probability distribution. We propose a
linear iterative method, which has the advantage that no assumptions on the
initial probability distribution is needed, and the only regularization
parameter is the stopping order of the iteration, which can be used to choose
the best compromise between the introduced bias and the propagated statistical
and systematic errors. The method is consistent: "binwise" convergence to the
initial probability distribution is proved in absence of measurement errors
under a quite general condition on the response function. This condition holds
for practical applications such as convolutions, calorimeter response
functions, momentum reconstruction response functions based on tracking in
magnetic field etc. In presence of measurement errors, explicit formulae for
the propagation of the three important error terms is provided: bias error,
statistical error, and systematic error. A trade-off between these three error
terms can be used to define an optimal iteration stopping criterion, and the
errors can be estimated there. We provide a numerical C library for the
implementation of the method, which incorporates automatic statistical error
propagation as well.Comment: Proceedings of ACAT-2011 conference (Uxbridge, United Kingdom), 9
pages, 5 figures, changes of corrigendum include
NövĂ©nyi jellegek Ă©s alkalmazásuk növĂ©nyökolĂłgiai kutatásokban I.: TörtĂ©neti áttekintĂ©s, jelleg tĂpusok, mĂłdszertan Ă©s adatbázisok = Plant functional traits and their application in ecological research I.: History, traits, methodologies and databases
Abstract: The importance of studies based on plant functional traits is indicated by the huge number of
papers (more than 5000) published in the last 15 years in this topic. In community ecology the recent
trend of studying organisms on the functional- rather than on the taxonomic level is quite significant. In
this review we attempted to summarise the applicability of functional plant traits commonly used in
ecological studies. We discussed the levels of functional categorisation, described the different plant
strategies based on functional traits and emphasised the usage of standardised measurements. The
most outstanding trait databases are introduced here, showing their availability, content and
specialities. This review is intended as an introduction to the topic and can later be completed by
papers elaborating on how plant functional traits are used in theoretical and applied plant ecology.
Keywords: functional ecology, growth-form, LEDA, life-form, plant strategies, SLA, TRY |
Összefoglalás: A növényi funkcionális jellegek kutatásának aktualitását mi sem jelzi jobban, mint az a
több mint 5000 publikáció, mely az utóbbi 15 évben megjelent a témában. A közösségi ökológia
számára ma már nélkülözhetetlen a fajok szintjén túlmutató funkcionális csoportok alkalmazása, ahol a
növényeket taxonómiai minőségük helyett funkcionális jellegeik alapján vizsgálják. Jelen dolgozatban
bemutatjuk a növĂ©nyökolĂłgiában leggyakrabban alkalmazott növĂ©nyi jellegeket, tĂpusaikat valamint az
általuk meghatározott növényi stratégiákat. Szót ejtünk a jellegek egységes mérésének módszertanáról,
illetve bemutatjuk a legfontosabb jellegadatbázisokat, és azok alkalmazási lehetőségeit. Jelen
dolgozatot a tĂ©ma bevezetĂ©sĂ©nek szánjuk, amit kĂ©sĹ‘bb olyan Ărások követhetnek, amelyek rĂ©szletesen
foglalkoznak a funkcionális jellegek gyakorlatban történő alkalmazásának lehetőségeivel.
Kulcsszavak: életforma, fajlagos levélfelület, funkcionális ökológia, LEDA, növekedési forma, növényi
stratégiák, TR
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