Search results for " spread"

Leading indicator properties of US high-yield credit spreads.

2010

Abstract In this paper we examine the out-of-sample forecast performance of high-yield credit spreads for real-time and revised data regarding employment and industrial production in the US. We evaluate models using both a point forecast and a probability forecast exercise. Our main findings suggest that the best results come from using only a few factors obtained by pooling information from a number of sector-specific high-yield credit spreads. In particular, for employment and at short-run horizons, there is a gain from using a principal components model fitted to high-yield credit spreads compared to the prediction produced by benchmarks. Moreover, forecast results based on revised data …

A Neurovascular Blood–Brain Barrier In Vitro Model

2014

The cerebral microvasculature possesses certain cellular features that constitute the blood-brain barrier (BBB) (Abbott et al., Neurobiol Dis 37:13-25, 2010). This dynamic barrier separates the brain parenchyma from peripheral blood flow and is of tremendous clinical importance: for example, BBB breakdown as in stroke is associated with the development of brain edema (Rosenberg and Yang, Neurosurg Focus 22:E4, 2007), inflammation (Kuhlmann et al., Neurosci Lett 449:168-172, 2009; Coisne and Engelhardt, Antioxid Redox Signal 15:1285-1303, 2011), and increased mortality. In vivo, the BBB consists of brain endothelial cells (BEC) that are embedded within a precisely regulated environment conta…

A Novel Wideband MIMO Car-to-Car Channel Model Based on a Geometrical Semi-Circular Tunnel Scattering Model

2016

In this paper, we present a wideband multiple-input multiple-output (MIMO) car-to-car (C2C) channel model based on a geometrical semi-circular tunnel (SCT) scattering model. From the geometrical SCT scattering model, a reference channel model is derived under the assumption of single-bounce scattering in line-of-sight (LOS) and non-LOS (NLOS) propagation environments. In the proposed reference channel model, it is assumed that an infinite number of scatterers are randomly distributed on the tunnel wall. Starting from the geometrical scattering model, the time-variant transfer function (TVTF) is derived, and its correlation properties in time, frequency, and space are studied. Expressions ar…

Peripheral Centralities: An Integrated Approach

2017

Un profondo cambiamento caratterizza a livello globale gli insediamenti urbani: ciò può essere osservato attraverso le relazioni tra centro e periferie. Le aree periferiche sono il banco dove il futuro delle città può essere opportunamente messo alla prova, in cui è possibile prefigurare la futura qualità della vita di individui e comunità. Sicurezza, sostenibilità, benessere che potranno essere raggiunti nelle aree periferiche saranno più rilevanti in termini quantitativi; invece il senso di identificazione e appartenenza, più forte nelle aree centrali, è debole o assente nelle periferie. Occorre puntare quindi a una sorta di centralità diffusa, applicando un approccio integrato, che si ad…

Narrowband digital filtering with random frequency hopping spread spectrum

2014

International audience; In digital signal filtering, channels with narrow bandwidth need high order digital filter to be selected without introducing modulation errors. If a carrier randomly switches from a channel to another as in military applications, or some civilian communication standards, it is necessary to detect and estimate these jumps before transposing and analyzing signals in the baseband. This paper presents a real time solution to filter narrow band signals with random frequency hopping spread spectrum. The proposed method is based on three steps. Firstly, the detection of Signal Frequency Hopping (SFH) using the Fast Fourier Transform (FFT), an algorithm to estimate the Domi…

Modelling the Doppler Power Spectrum of Non-Stationary Underwater Acoustic Channels Based on Doppler Measurements

2017

This paper proposes a non-stationary time-continuous simulation model for wideband shallow underwater acoustic (UWA) channels based on measured Doppler power spectrums (DPSs). Measurement-based channel simulators are essential for the test, optimization, and performance analysis of UWA communication systems. The aim is to fit the DPS of the simulation model to that of the measured UWA channel. The performance of the designed UWA channel simulator is assessed by comparing the average Doppler shift and Doppler spread of the channel simulator with the corresponding quantities of the measured UWA channel. The results of the assessment show a good match between the statistical quantities of the …

Temporal Dispersion Characterization of Over-Building Propagation Applied to Iso-Frequency Repeaters

2009

This letter presents the results of a measurements campaign carried out at 2050 MHz with the aim of characterizing the time dispersion of multipath propagation when the transmit and receive antennas are placed near and situated on rooftops or mounted on masts. The measurements were taken in four separate locations within the urban area of Madrid, Spain. From the measured data, the root mean square (RMS) value of the delay spread and the delay interval that characterize the time dispersion propagation of the environment under study are analyzed. An average power delay profile (PDP), representative of the time dispersion, is proposed so as to extrapolate these results to other similar environ…

A systematic review on external ear melanoma

2014

Summary Background External ear melanoma accounts for only 1% of all cutaneous melanomas, and data on its optimal management and prognosis are limited. Aim We aim to review the literature on external ear melanoma to guide surgeons in the treatment of this uncommon and peculiar pathology. Materials and methods A systematic review of English language studies on ear melanoma published from 1993 to 2013 was performed using the PubMed electronic database. Data on epidemiology, oncological treatment (tumor resection and regional lymph nodes management), and reconstruction were extrapolated from selected papers. Results The total number of patients was 858 (30 studies). The helix was the most comm…

Adapting FAO-56 Spreadsheet Program to estimate olive orchard transpiration fluxes under soil water stress condition

2012

Capture Aware Sequential Waterfilling for LoraWAN Adaptive Data Rate

2020

LoRaWAN (Long Range Wide Area Network) is emerging as an attractive network infrastructure for ultra low power Internet of Things devices. Even if the technology itself is quite mature and specified, the currently deployed wireless resource allocation strategies are still coarse and based on rough heuristics. This paper proposes an innovative "sequential waterfilling" strategy for assigning Spreading Factors (SF) to End-Devices (ED). Our design relies on three complementary approaches: i) equalize the Time-on-Air of the packets transmitted by the system's EDs in each spreading factor's group; ii) balance the spreading factors across multiple access gateways, and iii) keep into account the c…