141 research outputs found
Post-Meiotic Intra-Testicular Sperm Senescence in a Wild Vertebrate
There is growing interest in sperm senescence, both in its underlying mechanisms and evolutionary consequences, because
it can impact the evolution of numerous life history traits. Previous studies have documented various types of sperm
senescence, but evidence of post-meiotic intra-testicular sperm senescence in wild animals is lacking. To assess such
senescence, we studied within-season changes in sperm motility in the common toad (Bufo bufo), where males produce all
sperm prior to the breeding season. We found that males exposed to experimentally induced re-hibernation at the start of
the breeding season, that is to experimentally lowered metabolic rates, stored sperm of significantly higher motility than
males that were kept under seminatural conditions without females throughout the breeding season. This finding indicates
that re-hibernation slows normal rates of sperm ageing and constitutes the first evidence to our knowledge of post-meiotic
intra-testicular sperm senescence in a wild vertebrate. We also found that in males kept in seminatural conditions, sperm
motility was positively related to the number of matings a male achieved. Thus, our results suggest that post-meiotic intratesticular
sperm senescence does not have a genetically fixed rate and may be modulated by temperature and possibly by
mating opportunities
Vegetation and conservation of grasslands in Central-Europe – Editorial to the 12th EDGG Special Feature
Seit 12 Jahren werden von Mitgliedern der Eurasian Dry Grassland Group (EDGG) und deren Vor-gängerorganisationen Grasland-Sonderteile in Tuexenia herausgegeben. Der diesjährige Sonderteil enthält fünf Artikel, die das Grasland verschiedener mitteleuropäischer Länder mit unterschiedlichen Zielen untersuchen. Der erste Artikel untersucht Auswirkungen von Weide und Mahd auf die Diversität des Graslands in Deutschland in Abhängigkeit von verschiedenen Umweltfaktoren, der zweite die Auswirkung kleiner Büsche auf den Artenreichtum von Gefäßpflanzen in beweideten Wiesensteppen in Ungarn. Der dritte Artikel fragt, ob sich ungarische Sandtrockenrasen mit Festuca vaginata von solchen mit F. pseudovaginata in ihrer Vegetation und ihren Standortsbedingungen unterscheiden; die letztere war erst kürzlich beschrieben worden. Der vierte Artikel modelliert Auswirkungen des Klimawandels auf geschützte Graslandbestände in Serbien und deren Arten während schließlich der fünfte Artikel die Initiative einer neuen Datenbank des deutschen Graslands (GrassVeg.DE) vorstellt und dazu aufruft, sich daran zu beteiligen. Insgesamt haben zu diesem 12. Grasland-Sonderteil 41 Autoren aus fünf Ländern (Dänemark, Deutschland, Italien, Schweiz, Serbien und Ungarn) beigetragen
Standard-Based eLearning Solutions in Higher Education
Computer and Automation Research Institute, Hungarian
Academy of Sciences - further SZTAKI - has a really good and well-known
international technology/research background. Because of this good track
record SZTAKI has received the status of the EU Centre of Excellence in Information
Technology and Automation. According to these experiences the staff
of the eLearning Department is involved in several EU Leonardo, and
Hungarian Info-communication Technology projects. We started to monitor the
local eLearning market. The domestic eLearning projects have a typical
weakness so far, that the created training materials can be used only in a
specific Learning Management System - LMS. It is a big constrain and this
is why we decided to build up a systematic method to overcome this problem
Network-level architecture and the evolutionary potential of underground metabolism
A central unresolved issue in evolutionary biology is how metabolic innovations emerge. Low-level enzymatic side activities are frequent and can potentially be recruited for new biochemical functions. However, the role of such underground reactions in adaptation toward novel environments has remained largely unknown and out of reach of computational predictions, not least because these issues demand analyses at the level of the entire metabolic network. Here, we provide a comprehensive computational model of the underground metabolism in Escherichia coli. Most underground reactions are not isolated and 45% of them can be fully wired into the existing network and form novel pathways that produce key precursors for cell growth. This observation allowed us to conduct an integrated genome-wide in silico and experimental survey to characterize the evolutionary potential of E. coli to adapt to hundreds of nutrient conditions. We revealed that underground reactions allow growth in new environments when their activity is increased. We estimate that at least similar to 20% of the underground reactions that can be connected to the existing network confer a fitness advantage under specific environments. Moreover, our results demonstrate that the genetic basis of evolutionary adaptations via underground metabolism is computationally predictable. The approach used here has potential for various application areas from bioengineering to medical genetics
FGF2 and EGF induce epithelial-mesenchymal transition in malignant pleural mesothelioma cells via a MAPKinase/MMP1 signal
Malignant pleural mesothelioma (MPM), an aggressive malignancy affecting pleural surfaces, occurs in three main histological subtypes. The epithelioid and sarcomatoid subtypes are characterized by cuboid and fibroblastoid cells, respectively. The biphasic subtype contains a mixture of both. The sarcomatoid subtype expresses markers of epithelial-mesenchymal transition (EMT) and confers the worst prognosis, but the signals and pathways controlling EMT in MPM are not well understood. We demonstrate that treatment with FGF2 or EGF induced a fibroblastoid morphology in several cell lines from biphasic MPM, accompanied by scattering, decreased cell adhesion and increased invasiveness. This depended on the MAP-kinase pathway but was independent of TGF beta or PI3-kinase signaling. In addition to changes in known EMT markers, microarray analysis demonstrated differential expression of MMP1, ESM1, ETV4, PDL1 and BDKR2B in response to both growth factors and in epithelioid versus sarcomatoid MPM. Inhibition of MMP1 prevented FGF2-induced scattering and invasiveness. Moreover, in MPM cells with sarcomatoid morphology, inhibition of FGF/MAP-kinase signaling induced a more epithelioid morphology and gene expression pattern. Our findings suggest a critical role of the MAP-kinase axis in the morphological and behavioral plasticity of mesothelioma
Augmented Reality-based Robot Control for Laparoscopic Surgery
Minimally invasive surgery is the standard formany abdominal interventions, with an increasing use of tele-manipulated robots. As collaborative robots enter the field ofmedical interventions, their intuitive control needs to be ad-dressed. Augmented reality can thereby support a surgeonby representing the surgical scene in a natural way. In thiswork, an augmented reality based robot control for laparo-scopic cholecystectomy is presented. A user can interact withthe virtual scene to clip the cystic duct and artery as well asto manipulate the deformable gallbladder. An evaluation wasperformed based on the SurgTLX and system usability scale
The Supersymmetric Origin of Matter
The Minimal Supersymmetric extension of the Standard Model (MSSM) can provide
the correct neutralino relic abundance and baryon number asymmetry of the
universe. Both may be efficiently generated in the presence of CP violating
phases, light charginos and neutralinos, and a light top squark. Due to the
coannihilation of the neutralino with the light stop, we find a large region of
parameter space in which the neutralino relic density is consistent with WMAP
and SDSS data. We perform a detailed study of the additional constraints
induced when CP violating phases, consistent with the ones required for
baryogenesis, are included. We explore the possible tests of this scenario from
present and future electron Electric Dipole Moment (EDM) measurements, direct
neutralino detection experiments, collider searches and the b -> s gamma decay
rate. We find that the EDM constraints are quite severe and that electron EDM
experiments, together with stop searches at the Tevatron and Higgs searches at
the LHC, will provide a definite test of our scenario of electroweak
baryogenesis in the next few years.Comment: 30 pages, 14 figure
MOLYBDENUM DOPED CARBON AEROGELS WITH CATALYTIC POTENTIAL
Mo-doped carbon aerogels were obtained in the polycondensation reaction of aqueous
resorcinol and formaldehyde by adding Mo-salt at two different stages of the synthesis: i) to
the initial sol; ii) by incipient wetting impregnation of the supercritically dried polymer gel.
Molybdenum added during the polymerization yielded a more compact gel structure with
practically no mesoporosity. With post-impregnation, by contrast, mesopores of diameter 3-15
nm were generated. Carbonization appreciably enhanced the microporous character of both
samples, but in the mesopore range their pore size distribution was conserved. The Mocontent
of the samples was also different: Mo was lost during the solvent exchange before the
supercritical drying (i.e., the Mo failed to bind chemically to the polymer matrix). The
residual Mo congregated into 25-60 nm bulk clusters of α-Mo2C. In the other carbon aerogel,
finely dispersed α-Mo2C and η-Mo3C2 crystals formed, of size 8-20 nm. On the surface of
both carbons the Mo formed oxides. In the model test reaction (acetic acid hydroconversion)
the catalytic activity of both carbon aerogels was enhanced by molybdenum. The more open
pore structure, higher concentration and finer Mo distribution, as well as its chemical form,
may all be responsible for the greater conversion and higher value products obtained with the
post-impregnated sample
The Baryogenesis Window in the MSSM
Electroweak baryogenesis provides an attractive explanation of the origin of
the matter-antimatter asymmetry that relies on physics at the weak scale and
thus it is testable at present and near future high-energy physics experiments.
Although this scenario may not be realized within the Standard Model, it can be
accommodated within the MSSM provided there are new CP-violating phases and the
lightest stop mass is smaller than the top-quark mass. In this work we provide
an evaluation of the values of the stop (m_{\tilde t}) and Higgs (m_H) masses
consistent with the requirements of electroweak baryogenesis based on an
analysis that makes use of the renormalization group improved Higgs and stop
potentials, and including the dominant two-loop effects at high temperature. We
find an allowed window in the (m_{\tilde t},m_H)-plane, consistent with all
present experimental data, where there is a strongly first-order electroweak
phase transition and where the electroweak vacuum is metastable but
sufficiently long-lived. In particular we obtain absolute upper bounds on the
Higgs and stop masses, m_H\lesssim 127 GeV and m_{\tilde t}\lesssim 120 GeV,
implying that this scenario will be probed at the LHC.Comment: 26 pages, 6 figures; comments adde
LHC Discovery Potential for Non-Standard Higgs Bosons in the 3b Channel
In a variety of well motivated models, such as two Higgs Doublet Models
(2HDMs) and the Minimal Supersymmetric Standard Model (MSSM), there are neutral
Higgs bosons that have significantly enhanced couplings to b-quarks and tau
leptons in comparison to those of the SM Higgs. These so called non-standard
Higgs bosons could be copiously produced at the LHC in association with b
quarks, and subsequently decay into b-quark pairs. However, this production
channel suffers from large irreducible QCD backgrounds. We propose a new search
strategy for non-standard neutral Higgs bosons at the 7 TeV LHC in the 3b's
final state topology. We perform a simulation of the signal and backgrounds,
using state of the art tools and methods for different sets of selection cuts,
and conclude that neutral Higgs bosons with couplings to b-quarks of about 0.3
or larger, and masses up to 400 GeV, could be seen with a luminosity of 30
fb^{-1}. In the case of the MSSM we also discuss the complementarity between
the 3b channel and the inclusive tau pair channel in exploring the
supersymmetric parameter space.Comment: 14 pages, 3 figures, 4 tables, references added, published versio
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