7,131 research outputs found
A Multifrequency Analysis of the Polarized Diffuse Galactic Radio Emission at Degree Scales
The polarized diffuse Galactic radio emission, mainly synchrotron emission,
is expected to be one of the most relevant source of astrophysical
contamination at low and moderate multipoles in cosmic microwave background
polarization anisotropy experiments at frequencies lower then 50 to 100 GHz. We
present here preliminary results based on a recent analysis of the Leiden
surveys covering about 50% of the sky at low as well as at middle and high
Galactic latitudes. By implementing specific interpolation methods to deal with
these data, which show a large variation of the sampling across the sky, we
produce maps of the polarized diffuse Galactic synchrotron component at
frequencies between 408 and 1411 MHz with pixel sizes larger or equal to about
0.92 degrees. We derive the angular power spectrum of this component for the
whole covered region and for three patches in the sky significantly oversampled
with respect to the average and at different Galactic latitudes. We find
multipole spectral indices typically ranging between about -3 and about -1,
according to the considered frequency and sky region. At frequencies higher or
equal to 610 MHz, the frequency spectral indices observed in the considered sky
regions are about -3.5, compatible with an intrinsic frequency spectral index
of about -5.8 and a depolarization due to Faraday rotation with a rotation
measure RM of about 15 radians per square meter. This implies that the observed
angular power spectrum of the polarized signal is about 85% or 20% of the
intrinsic one at 1411 MHz or 820 MHz respectively.Comment: 6 pages, 5 figures. to appear in S.Cecchini et al., Astrophysical
Polarized Backgrounds, AIP Conf. Proceeding
Do Institutions Cause Growth?
We revisit the debate over whether political institutions cause economic growth, or whether, alternatively, growth and human capital accumulation lead to institutional improvement. We find that most indicators of institutional quality used to establish the proposition that institutions cause growth are constructed to be conceptually unsuitable for that purpose. We also find that some of the instrumental variable techniques used in the literature are flawed. Basic OLS results, as well as a variety of additional evidence, suggest that a) human capital is a more basic source of growth than are the institutions, b) poor countries get out of poverty through good policies, often pursued by dictators, and c) subsequently improve their political institutions.
The New Comparative Economics
In recent years, comparative economics experienced a revival, with a new focus on comparing capitalist economies. The theme of the new research is that institutions exert a profound influence on economic development. We argue that, to understand capitalist institutions, one needs to understand the basic tradeoff between the costs of disorder and those of dictatorship. We then apply this logic to study the structure of efficient institutions, the consequences of colonial transplantation, and the politics of institutional choice.
The New Comparative Economics
In recent years, comparative economics experienced a revival, with a new focus on comparing capitalist economies. The theme of the new research is that institutions exert a profound influence on economic development. We argue that, to understand capitalist institutions, one needs to understand the basic tradeoff between the costs of disorder and those of dictatorship. We then apply this logic to study the structure of efficient institutions, the consequences of colonial transplantation, and the politics of institutional choice.
Ecological effects of the European barbel Barbus barbus (L., 1758) (Cyprinidae) invasion on native barbel populations in the Tiber River basin (Italy)
The purpose of this study was to investigate the effects of the European barbel Barbus barbus (L., 1758) invasion in the Tiber River basin (Italy) on the native Tiber barbel Barbus tyberinus Bonaparte, 1839, verifying whether the co-occurrence played a negative impact on growth rate and relative weight. Fish census data were collected during three periods (2000–2005, 2006–2010, 2011–2015) at 158 sampling sites. Since its first record in 1998, European barbel rapidly spread in the study area: it was present in more than 20% of the monitoring sites, where it is leading to the gradual replacement of Tiber barbel by widening its distribution in the Tiber River and in the downstream reaches of the main tributaries. By contrast, Tiber barbel has suffered from this competition, as demonstrated by the fact that the mean value of the relative weight was significantly higher where European barbel was absent. The results obtained suggested that this non-native species could be a serious threat to the conservation status of endemic Tiber barbel, and constitute the premise to underpin conservation strategies aiming to preserve native freshwater biodiversity
An angular power spectrum analysis of the DRAO 1.4 GHz polarization survey: implications for CMB observations
The aim of the present analysis is to improve the knowledge of the
statistical properties of the Galactic diffuse synchrotron emission, which
constrains sensitive CMB anisotropy measurements. We have analysed the new DRAO
1.4 GHz polarization survey together with the Stockert 1.4 GHz total intensity
survey and derived the angular power spectra (APSs) of the total intensity, the
polarized emission, and their cross-correlation for the entire surveys and for
three low-intensity regions. The APSs of the diffuse synchrotron emission are
modelled by power laws. For the and modes, a slope of for the multipole range is found. By the
extrapolation of these results to 70 GHz, we can estimate the Galactic
synchrotron contamination of CMB anisotropies, and we find results that are
compatible with the ones coming from WMAP 3-yr data. In the low-intensity
regions, the cosmological primordial B~mode peak at should be
clearly observable for a tensor-to-scalar ratio T/S \gsim 0.5 and a
synchrotron temperature spectral index . Its detection is also
possible for T/S \gsim 0.005 and , in case a separation of the
foreground from the CMB signal could be achieved with an accuracy of . For the TE mode, a mask excluding (for
) or (for ) from the
surveys is sufficient to render the foreground contamination negligible, thus
confirming the ability of WMAP to have a clear view of the
temperature-polarization correlation peak and antipeak series.Comment: 4 pages, 5 figures, will appear on A&A Let
Early identification of root rot disease by using hyperspectral reflectance: the case of pathosystem grapevine/Armillaria
Armillaria genus represents one of the most common causes of chronic root rot disease in woody plants. Prompt recognition of diseased plants is crucial to control the pathogen. However, the current disease detection methods are limited at a field scale. Therefore, an alternative approach is needed. In this study, we investigated the potential of hyperspectral techniques to identify fungi-infected vs. healthy plants of Vitis vinifera. We used the hyperspectral imaging sensor Specim-IQ to acquire leaves’ reflectance data of the Teroldego Rotaliano grapevine cultivar. We analyzed three different groups of plants: healthy, asymptomatic, and diseased. Highly significant differences were found in the near-infrared (NIR) spectral region with a decreasing pattern from healthy to diseased plants attributable to the leaf mesophyll changes. Asymptomatic plants emerged from the other groups due to a lower reflectance in the red edge spectrum (around 705 nm), ascribable to an accumulation of secondary metabolites involved in plant defense strategies. Further significant differences were observed in the wavelengths close to 550 nm in diseased vs. asymptomatic plants. We evaluated several machine learning paradigms to differentiate the plant groups. The Naïve Bayes (NB) algorithm, combined with the most discriminant variables among vegetation indices and spectral narrow bands, provided the best results with an overall accuracy of 90% and 75% in healthy vs. diseased and healthy vs. asymptomatic plants, respectively. To our knowledge, this study represents the first report on the possibility of using hyperspectral data for root rot disease diagnosis in woody plants. Although further validation studies are required, it appears that the spectral reflectance technique, possibly implemented on unmanned aerial vehicles (UAVs), could be a promising tool for a cost-effective, non-invasive method of Armillaria disease diagnosis and mapping in-field, contributing to a significant step forward in precision viticultur
Tunneling into granular Pb films in the superconducting and insulating regimes
Tunneling measurements have been performed on both sides of the insulator-superconductor transition in quench-condensed granular Pb films. The results indicate that the Pb film consists of fully superconducting grains with essentially bulk values for the superconducting energy gap and transition temperature, even when the film exhibits insulating behavior in transport measurements. The density of states inferred from measurements in perpendicular magnetic field are consistent with magnetic spin-flip broadening
Improved copper–epoxy adhesion by laser micro- and nano-structuring of copper surface for thermal applications
The objective of this work is the enhancement of metal-to-metal bonding to provide high thermal conductivity together with electrical insulation, to be used as heat sinks at room and cryo-genic temperatures. High thermal conductive metal (copper) and epoxy resin (Stycast 2850FT) were used in this study, with the latter also providing the required electrical insulation. The copper surface was irradiated with laser to induce micro- and nano-patterned structures that result in an improvement of the adhesion between the epoxy and the copper. Thus, copper-to-copper bonding strength was characterized by means of mechanical tensile shear tests. The effect of the laser processing on the thermal conductivity properties of the Cu/epoxy/Cu joint at different temperatures, from 10 to 300 K, is also reported. Using adequate laser parameters, it is possible to obtain high bonding strength values limited by cohesive epoxy fracture, together with good thermal conductivity at ambient and cryogenic temperatures. © 2021 by the authors. Licensee MDPI, Basel, Switzerland
Feasibility interventional study investigating PAIN in neurorehabilitation through wearabLE SensorS (PAINLESS): a study protocol
Introduction: Millions of people survive injuries to the central or peripheral nervous system for which neurorehabilitation is required. In addition to the physical and cognitive impairments, many neurorehabilitation patients experience pain, often not widely recognised and inadequately treated. This is particularly true for multiple sclerosis (MS) patients, for whom pain is one of the most common symptoms. In clinical practice, pain assessment is usually conducted based on a subjective estimate. This approach can lead to inaccurate evaluations due to the influence of numerous factors, including emotional or cognitive aspects. To date, no objective and simple to use clinical methods allow objective quantification of pain and the diagnostic differentiation between the two main types of pain (nociceptive vs neuropathic). Wearable technologies and artificial intelligence (AI) have the potential to bridge this gap by continuously monitoring patients' health parameters and extracting meaningful information from them. Therefore, we propose to develop a new automatic AI-powered tool to assess pain and its characteristics during neurorehabilitation treatments using physiological signals collected by wearable sensors. Methods and analysis: We aim to recruit 15 participants suffering from MS undergoing physiotherapy treatment. During the study, participants will wear a wristband for three consecutive days and be monitored before and after their physiotherapy sessions. Measurement of traditionally used pain assessment questionnaires and scales (ie, painDETECT, Doleur Neuropathique 4 Questions, EuroQoL-5-dimension-3-level) and physiological signals (photoplethysmography, electrodermal activity, skin temperature, accelerometer data) will be collected. Relevant parameters from physiological signals will be identified, and AI algorithms will be used to develop automatic classification methods. Ethics and dissemination: The study has been approved by the local Ethical Committee (285-2022-SPER-AUSLBO). Participants are required to provide written informed consent. The results will be disseminated through contributions to international conferences and scientific journals, and they will also be included in a doctoral dissertation. Trial registration number: NCT05747040
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