714 research outputs found
Information Theoretic Operating Regimes of Large Wireless Networks
In analyzing the point-to-point wireless channel, insights about two
qualitatively different operating regimes--bandwidth- and power-limited--have
proven indispensable in the design of good communication schemes. In this
paper, we propose a new scaling law formulation for wireless networks that
allows us to develop a theory that is analogous to the point-to-point case. We
identify fundamental operating regimes of wireless networks and derive
architectural guidelines for the design of optimal schemes.
Our analysis shows that in a given wireless network with arbitrary size,
area, power, bandwidth, etc., there are three parameters of importance: the
short-distance SNR, the long-distance SNR, and the power path loss exponent of
the environment. Depending on these parameters we identify four qualitatively
different regimes. One of these regimes is especially interesting since it is
fundamentally a consequence of the heterogeneous nature of links in a network
and does not occur in the point-to-point case; the network capacity is {\em
both} power and bandwidth limited. This regime has thus far remained hidden due
to the limitations of the existing formulation. Existing schemes, either
multihop transmission or hierarchical cooperation, fail to achieve capacity in
this regime; we propose a new hybrid scheme that achieves capacity.Comment: 12 pages, 5 figures, to appear in IEEE Transactions on Information
Theor
Robust Task and Motion Planning for Long-Horizon Architectural Construction Planning
Integrating robotic systems in architectural and construction processes is of
core interest to increase the efficiency of the building industry. Automated
planning for such systems enables design analysis tools and facilitates faster
design iteration cycles for designers and engineers. However, generic
task-and-motion planning (TAMP) for long-horizon construction processes is
beyond the capabilities of current approaches. In this paper, we develop a
multi-agent TAMP framework for long horizon problems such as constructing a
full-scale building. To this end we extend the Logic-Geometric Programming
framework by sampling-based motion planning,a limited horizon approach, and a
task-specific structural stability optimization that allow an effective
decomposition of the task. We show that our framework is capable of
constructing a large pavilion built from several hundred geometrically unique
building elements from start to end autonomously
Podwójne znakowanie immunologiczne CD133 i Ki-67 wskazuje na ich istotną współlokalizację w podtypie włóknistym oponiaków
Background and purpose
A unique molecular and/or cellular marker for meningiomas, the most common intracranial tumours, has not been identified yet.
Material and methods
We investigated the co-localization fraction of CD133/Ki-67 in meningioma tissue array slide composed of 80 meningioma tissue samples of various histological variants. CD133 – a cell membrane stem cell marker – was previously proved to be associated with the initiation and progression of intracerebral gliomas and medulloblastomas.
Results
Immunohistochemical co-localization of CD133/Ki-67 was significantly higher in fibroblastic variant than in meningothelial and transitional subtypes. However, since there were only 3 atypical and 1 malignant meningioma spots in the tumour tissue array slide, it is difficult to draw a firm conclusion regarding the actual co-localization percentage and persistence of CD133/Ki-67 in atypical and malignant meningiomas.
Conclusions
Far higher co-staining percentage of CD133/Ki-67 in fibroblastic meningioma samples compared to meningothelial subtype, a histological meningioma variant, architectonically resembling the non-neoplastic meningeal cells, gave us the impression that CD133 may play a role in the formation and progression of fibroblastic meningioma variants. The persistency and the validity of this finding need to be verified by further histopathological and molecular research in order to clarify the possible role of CD133 in meningiogenesis.Wstęp i cel pracy
Nie określono dotąd unikalnego znacznika molekularnego lub komórkowego dla oponiaków, najczęstszych guzów wewnątrzczaszkowych. Wcześniej wykazano, że CD133 – znacznik błony komórkowej komórek macierzystych – jest związany z zapoczątkowaniem, a także wzrostem wewnątrzczaszkowych glejaków i rdzeniaków płodowych.
Materiał i metody
Zbadano odsetek współlokalizacji CD133/Ki-67 w zestawach macierzy tkankowych oponiaków, złożonych z próbek 80 rozmaitych odmian histologicznych oponiaków.
Wyniki
Immunohistochemiczna współlokalizacja CD133 i Ki-67 była stwierdzana istotnie częściej w podtypie włóknistym oponiaka niż w podtypach meningotelialnym lub przejściowym. Ze względu na małą liczbę preparatów opo-niaków atypowych (3) oraz złośliwych (1) w badanej macierzy tkankowej trudno wyciągnąć jednoznaczne wnioski dotyczące rzeczywistego odsetka współlokalizacji i utrzymywania się CD133/Ki-67 w oponiakach atypowych i złośliwych.
Wnioski
Znacząco większy odsetek wspólnie występującej reaktywności CD133/Ki-67 w preparatach oponiaka włóknistego w porównaniu z podtypem meningotelialnym, którego architektonika przypomina nienowotworowe komórki opon, sprawia wrażenie, że CD133 może odgrywać rolę w powstawaniu i rozwoju oponiaków włóknistych. Trafność tego spostrzeżenia wymaga weryfikacji w dalszych badaniach histopatologicznych i molekularnych w celu wyjaśnienia możliwej roli CD133 w powstawaniu oponiaków
Weak field and slow motion limits in energy-momentum powered gravity
We explore the weak field and slow motion limits, Newtonian and
Post-Newtonian limits, of the energy-momentum powered gravity (EMPG), viz., the
energy-momentum squared gravity (EMSG) of the form
with
and being constants. We have shown that EMPG with and
general relativity (GR) are not distinguishable by local tests, say, the Solar
System tests; as they lead to the same gravitational potential form, PPN
parameters, and geodesics for the test particles. However, within the EMPG
framework, , the mass of an astrophysical object inferred from
astronomical observations such as planetary orbits and deflection of light,
corresponds to the effective mass , being the actual physical mass and
being the modification due to EMPG. Accordingly, while in GR we simply have the
relation , in EMPG we have . Within
the framework of EMPG, if there is information about the values of
pair or from other independent phenomena (from
cosmological observations, structure of the astrophysical object, etc.), then
in principle it is possible to infer not only alone from
astronomical observations, but and separately. For a proper
analysis within EMPG framework, it is necessary to describe the slow motion
condition (also related to the Newtonian limit approximation) by (where and ), whereas this condition leads to in
GR.Comment: 12 pages, no figures and table
Screening in a new modified gravity model
We study a new model of Energy-Momentum Squared Gravity (EMSG), called
Energy-Momentum Log Gravity (EMLG), constructed by the addition of the term
, envisaged
as a correction, to the Einstein-Hilbert action with cosmological constant
. The choice of this modification is made as a specific way of
including new terms in the right-hand side of the Einstein field equations,
resulting in constant effective inertial mass density and, importantly, leading
to an explicit exact solution of the matter energy density in terms of
redshift. We look for viable cosmologies, in particular, an extension of the
standard CDM model. EMLG provides an effective dynamical dark energy
passing below zero at large redshifts, accommodating a mechanism for screening
in this region, in line with suggestions for alleviating some of the
tensions that arise between observational data sets within the standard
CDM model. We present a detailed theoretical investigation of the
model and then constrain the free parameter , a normalisation of
, using the latest observational data. The data does not rule out the
CDM limit of our model (), but prefers slightly negative
values of the EMLG model parameter (), which leads to
the screening of . We also discuss how EMLG relaxes the persistent
tension that appears in the measurements of within the standard
CDM model.Comment: 17 pages, 11 figures, 1 table; matches the version published in EPJ
Default Risk and Equity Returns: A Comparison of the Bank-Based German and the U.S. Financial System
In this paper, we address the question whether the impact of default risk on equity returns depends on the financial system firms operate in. Using an implementation of Merton's option-pricing model for the value of equity to estimate firms' default risk, we construct a factor that measures the excess return of firms with low default risk over firms with high default risk. We then compare results from asset pricing tests for the German and the U.S. stock markets. Since Germany is the prime example of a bank-based financial system, where debt is supposedly a major instrument of corporate governance, we expect that a systematic default risk effect on equity returns should be more pronounced for German rather than U.S. firms. Our evidence suggests that a higher firm default risk systematically leads to lower returns in both capital markets. This contradicts some previous results for the U.S. by Vassalou/Xing (2004), but we show that their default risk factor looses its explanatory power if one includes a default risk factor measured as a factor mimicking portfolio. It further turns out that the composition of corporate debt affects equity returns in Germany. Firms' default risk sensitivities are attenuated the more a firm depends on bank debt financing
NAC transcription factor JUNGBRUNNEN1 enhances drought tolerance in tomato
FWN – Publicaties zonder aanstelling Universiteit Leide
Kemijski sastav endemske biljke Centaurea austro-anatolica i ispitivanje antimikrobnog djelovanja protiv multi-rezistentnih bakterija
Hexane, chloroform, ethyl acetate and ethanolic extracts of the aerial parts of C. austro-anatolica Hub.-Mor. (Asteraceae) were evaluated against microorganisms, including multi-resistant bacteria, using a paper disc diffusion method. The chloroform extract exhibited significant antibacterial activity toward all bacteria tested. The chemical composition of the chloroform extract was determined by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The major compounds of the extract were caryophyllene oxide (21.32 %), spathulenol (10.86 %), n-tricosanol (9.58 %) and geranyl isovalerate (8.71 %).Heksanski, kloroformski, etil-acetatni i etanolni ekstrakti vršnih dijelova biljke C. austro-anatolica Hub.-Mor. (Asteraceae) ispitivani su na antimikrobno djelovanje protiv multi-rezistentnih bakterija, koristeći difuzijsku metodu na papirnom disku. Kloroformski ekstrakt pokazao je značajno antibakterijsko djelovanje protiv svih testiranih bakterija. Kemijski sastav tog ekstrakta određivan je plinskom kromatografijom (GC) i plinskom kromatografijom-spektrometrijom masa (GC-MS). Najvažniji sastojci ekstrakta bili su kariofilen oksid (21,32 %), spatulenol (10,86 %), n-trikozanol (9,58 %) i geranil izovalerat (8,71 %)
Assessing the Impact of EEE Standard on Energy Consumed by Commercial Grade Network Switches
This book chapter is adapted from [1] and it is closely linked to work published in [2] and [3]. Reducing power consumption of network equipment has been both driven by a need to reduce the ecological footprint of the cloud as well as the im-mense power costs of data centers. As data centers, core networks and conse-quently, the cloud, constantly increase in size, their power consumption should be mitigated. Ethernet, the most widely used access network still remains the biggest communication technology used in core networks and cloud infrastructures. The Energy-Efficient Ethernet or EEE standard introduced by IEEE in 2010, aims to reduce the power consumption of EEE ports by transitioning Ethernet ports into a low power mode when traffic is not present. As statistics show that the average utilization rate of ethernet links is 5 percent on desktops and 30 percent in data centers, the power saving potential of EEE could be immense. This research aims to assess the benefits of deploying EEE and create a power consumption model for network switches with and without EEE. Our measurements show that an EEE port runs at 12-15% of its total power when in low power mode. Therefore, the power savings can exceed 80% when there is no traffic. However, our measure-ments equally show that the power consumption of a single port represents less than 1% of the total power consumption of the switch. The base power consumed by the switch without any port is still significantly high and is not affected by EEE. Experiment results also show that the base power consumption of switches does not significantly increase with the size of the switches. Doubling the size of the switch between 24 and 48 ports increases power consumption by 35.39%. EEE has a greater effect on bigger switches, with a power (or energy) gain on the EEE-enabled 48-port switch compared to 2 x EEE-enabled 24-port switch. On the other hand, it seems to be more energy efficient to use 2 separate 24-port switches (NO EEE) than 2 separate 24-port switches (With EEE)
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