759 research outputs found

    Mandate-driven networking eco-system : a paradigm shift in end-to-end communications

    Get PDF
    The wireless industry is driven by key stakeholders that follow a holistic approach of "one-system-fits-all" that leads to moving network functionality of meeting stringent End-to-End (E2E) communication requirements towards the core and cloud infrastructures. This trend is limiting smaller and new players for bringing in new and novel solutions. For meeting these E2E requirements, tenants and end-users need to be active players for bringing their needs and innovations. Driving E2E communication not only in terms of quality of service (QoS) but also overall carbon footprint and spectrum efficiency from one specific community may lead to undesirable simplifications and a higher level of abstraction of other network segments may lead to sub-optimal operations. Based on this, the paper presents a paradigm shift that will enlarge the role of wireless innovation at academia, Small and Medium-sized Enterprises (SME)'s, industries and start-ups while taking into account decentralized mandate-driven intelligence in E2E communications

    Formation energy and interaction of point defects in two-dimensional colloidal crystals

    Full text link
    The manipulation of individual colloidal particles using optical tweezers has allowed vacancies to be created in two-dimensional (2d) colloidal crystals, with unprecedented possibility of real-time monitoring the dynamics of such defects (Nature {\bf 413}, 147 (2001)). In this Letter, we employ molecular dynamics (MD) simulations to calculate the formation energy of single defects and the binding energy between pairs of defects in a 2d colloidal crystal. In the light of our results, experimental observations of vacancies could be explained and then compared to simulation results for the interstitial defects. We see a remarkable similarity between our results for a 2d colloidal crystal and the 2d Wigner crystal (Phys. Rev. Lett. {\bf 86}, 492 (2001)). The results show that the formation energy to create a single interstitial is 1212% - 28% lower than that of the vacancy. Because the pair binding energies of the defects are strongly attractive for short distances, the ground state should correspond to bound pairs with the interstitial bound pairs being the most probable.Comment: 5 pages, 2 figure

    Optical constants of magnetron-sputtered magnesium films in the 25-1300 eV energy range

    Get PDF
    The transmittance of dc magnetron-sputtered Mg thin films was measured in the 25-1300 eV spectral range. Freestanding Mg films protected with Al layers were characterized ex situ. Transmittance measurements were used to obtain the extinction coefficient k of Mg films. The obtained k values along with the data available in the literature, and with interpolations and extrapolations for the rest of the spectrum, were used to obtain the real part of the index of refraction n by the Kramers-Krönig analysis. Sum-rule tests indicated a good consistency of the data. © 2010 American Institute of Physics.Peer Reviewe

    Finite-size scaling considerations on the ground state microcanonical temperature in entropic sampling simulations

    Full text link
    In this work we discuss the behavior of the microcanonical temperature S(E)E\frac{\partial S(E)}{\partial E} obtained by means of numerical entropic sampling studies. It is observed that in almost all cases the slope of the logarithm of the density of states S(E)S(E) is not infinite in the ground state, since as expected it should be directly related to the inverse temperature 1T\frac{1}{T}. Here we show that these finite slopes are in fact due to finite-size effects and we propose an analytic expression aln(bL)a\ln(bL) for the behavior of ΔSΔE\frac{\varDelta S}{\varDelta E} when LL\rightarrow\infty. To test this idea we use three distinct two-dimensional square lattice models presenting second-order phase transitions. We calculated by exact means the parameters aa and bb for the two-states Ising model and for the q=3q=3 and 44 states Potts model and compared with the results obtained by entropic sampling simulations. We found an excellent agreement between exact and numerical values. We argue that this new set of parameters aa and bb represents an interesting novel issue of investigation in entropic sampling studies for different models

    Determination of pulsation periods and other parameters of 2875 stars classified as MIRA in the All Sky Automated Survey (ASAS)

    Full text link
    We have developed an interactive PYTHON code and derived crucial ephemeris data of 99.4% of all stars classified as 'Mira' in the ASAS data base, referring to pulsation periods, mean maximum magnitudes and, whenever possible, the amplitudes among others. We present a statistical comparison between our results and those given by the AAVSO International Variable Star Index (VSX), as well as those determined with the machine learning automatic procedure of Richards et al. 2012. Our periods are in good agreement with those of the VSX in more than 95% of the stars. However, when comparing our periods with those of Richards et al, the coincidence rate is only 76% and most of the remaining cases refer to aliases. We conclude that automatic codes require still more refinements in order to provide reliable period values. Period distributions of the target stars show three local maxima around 215, 275 and 330 d, apparently of universal validity, their relative strength seems to depend on galactic longitude. Our visual amplitude distribution turns out to be bimodal, however 1/3 of the targets have rather small amplitudes (A << 2.5m^{m}) and could refer to semi-regular variables (SR). We estimate that about 20% of our targets belong to the SR class. We also provide a list of 63 candidates for period variations and a sample of 35 multiperiodic stars which seem to confirm the universal validity of typical sequences in the double period and in the Petersen diagramsComment: 14 pages, 14 figures, and 8 tables. Accepted to The Astrophysical Journal Supplement Series, September 201

    Resolving the temporal evolution of line broadening in single quantum emitters

    Get PDF
    Light emission from solid-state quantum emitters is inherently prone to environmental decoherence, which results in a line broadening and in the deterioration of photon indistinguishability. Here we employ photon correlation Fourier spectroscopy (PCFS) to study the temporal evolution of such a broadening in two prominent systems: GaAs and In(Ga)As quantum dots. Differently from previous experiments, the emitters are driven with short laser pulses as required for the generation of high-purity single photons, the time scales we probe range from a few nanoseconds to milliseconds and, simultaneously, the spectral resolution we achieve can be as small as ∼ 2µeV. We find pronounced differences in the temporal evolution of different optical transition lines, which we attribute to differences in their homogeneous linewidth and sensitivity to charge noise. We analyze the effect of irradiation with additional white light, which reduces blinking at the cost of enhanced charge noise. Due to its robustness against experimental imperfections and its high temporal resolution and bandwidth, PCFS outperforms established spectroscopy techniques, such as Michelson interferometry. We discuss its practical implementation and the possibility to use it to estimate the indistinguishability of consecutively emitted single photons for applications in quantum communication and photonic-based quantum information processing

    Reduced basal ganglia μ-opioid receptor availability in trigeminal neuropathic pain: A pilot study

    Full text link
    Abstract Background Although neuroimaging techniques have provided insights into the function of brain regions involved in Trigeminal Neuropathic Pain (TNP) in humans, there is little understanding of the molecular mechanisms affected during the course of this disorder. Understanding these processes is crucial to determine the systems involved in the development and persistence of TNP. Findings In this study, we examined the regional μ-opioid receptor (μOR) availability in vivo (non-displaceable binding potential BPND) of TNP patients with positron emission tomography (PET) using the μOR selective radioligand [11C]carfentanil. Four TNP patients and eight gender and age-matched healthy controls were examined with PET. Patients with TNP showed reduced μOR BPND in the left nucleus accumbens (NAc), an area known to be involved in pain modulation and reward/aversive behaviors. In addition, the μOR BPND in the NAc was negatively correlated with the McGill sensory and total pain ratings in the TNP patients. Conclusions Our findings give preliminary evidence that the clinical pain in TNP patients can be related to alterations in the endogenous μ-opioid system, rather than only to the peripheral pathology. The decreased availability of μORs found in TNP patients, and its inverse relationship to clinical pain levels, provide insights into the central mechanisms related to this condition. The results also expand our understanding about the impact of chronic pain on the limbic system.http://deepblue.lib.umich.edu/bitstream/2027.42/112555/1/12990_2012_Article_533.pd

    Phase II Study of Cediranib in Patients with Malignant Pleural Mesothelioma: SWOG S0509

    Get PDF
    IntroductionMalignant pleural mesothelioma (MPM) tumors express vascular epithelial growth factor (VEGF) and VEGF receptors. We conducted a phase II study of the oral pan-VEGF receptor tyrosine kinase inhibitor, cediranib, in patients with MPM after platinum-based systemic chemotherapy.MethodsPatients with MPM previously treated with a platinum-containing chemotherapy regimen and a performance status 0 to 2 were eligible for enrollment. Cediranib 45 mg/d was administered until progression or unacceptable toxicity. The primary end point was response rate. Tumor measurements were made by RECIST criteria, with a subset analysis conducted using modified RECIST. A two-stage design with an early stopping rule based on response rate was used.ResultsFifty-four patients were enrolled. Of 47 evaluable patients, 4 patients (9%) had objective responses, 16 patients (34%) had stable disease, 20 patients (43%) had disease progression, 2 patients (4%) had symptomatic deterioration, and 1 patient (2%) had early death. The most common toxicities were fatigue (64%), diarrhea (64%), and hypertension (70%); 91% of patients required a dose reduction. Median overall survival was 9.5 months, 1-year survival was 36%, and median progression-free survival was 2.6 months.ConclusionCediranib monotherapy has modest single-agent activity in MPM after platinum-based therapy. However, some patient tumors were highly sensitive to cediranib. This study provides a rationale for further testing of cediranib plus chemotherapy in MPM and highlights the need to identify a predictive biomarker for cediranib
    corecore