4,699 research outputs found

    Capital Flows and Destabilizing Policy in Latin America

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    Motivated by the excessive macroeconomic volatility experienced in Latin America, we examine the possible contribution of monetary and fiscal policies to this outcome. In contrast with previous literature, we consider the possible simultaneity between policy and GDP growth by using GMM VAR econometric techniques. Additionally, we explore the direct impact international capital inflows have on these policies. Our evidence suggests that for the group of countries we consider, most practice destabilizing fiscal and monetary policy, and capital inflow consistently influences policy in a pro-cyclical direction.Fiscal and Monetary Policies, Capital Flows, Latin America

    Gravitational waves from pulsars with measured braking index

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    We study the putative emission of gravitational waves (GWs) in particular for pulsars with measured braking index. We show that the appropriate combination of both GW emission and magnetic dipole brakes can naturally explain the measured braking index, when the surface magnetic field and the angle between the magnetic dipole and rotation axes are time dependent. Then we discuss the detectability of these very pulsars by aLIGO and the Einstein Telescope. We call attention to the realistic possibility that aLIGO can detect the GWs generated by at least some of these pulsars, such as Vela, for example.Comment: 6 pages and 4 figure

    Finance and the Business Cycle: a Kalman Filter Approach with Markov Switching

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    This paper combines two popular econometric tools, the dynamic factor model and the Markov-Switching model, to consider three segments of the financial system- the stock market, debt, and money- and their contribution to US business cycles over the past four decades. The dynamic factor model identifies a composite factor index for each financial segment, and using Markov-switching models by Hamilton (1989) and Filardo (1994), this paper then estimates the effect of each segment index on business cycle behaviour. This reexamination of the finance-business cycle link provides results that prove strongest for the effect of stock market movements on business cycles.

    Optimal Time-dependent Sequenced Route Queries in Road Networks

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    In this paper we present an algorithm for optimal processing of time-dependent sequenced route queries in road networks, i.e., given a road network where the travel time over an edge is time-dependent and a given ordered list of categories of interest, we find the fastest route between an origin and destination that passes through a sequence of points of interest belonging to each of the specified categories of interest. For instance, considering a city road network at a given departure time, one can find the fastest route between one's work and his/her home, passing through a bank, a supermarket and a restaurant, in this order. The main contribution of our work is the consideration of the time dependency of the network, a realistic characteristic of urban road networks, which has not been considered previously when addressing the optimal sequenced route query. Our approach uses the A* search paradigm that is equipped with an admissible heuristic function, thus guaranteed to yield the optimal solution, along with a pruning scheme for further reducing the search space. In order to compare our proposal we extended a previously proposed solution aimed at non-time dependent sequenced route queries, enabling it to deal with the time-dependency. Our experiments using real and synthetic data sets have shown our proposed solution to be up to two orders of magnitude faster than the temporally extended previous solution.Comment: 10 pages, 12 figures To be published as a short paper in the 23rd ACM SIGSPATIA

    Improving incremental encoder measurement: variable acquisition window and quadrature phase compensation to minimize acquisition errors

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    Motion control is an important task in several areas, such as robotics where the angular position and speed should be acquired, usually with encoders. For slow angular speeds, an error is introduced spoiling the measurement. In this paper there will be proposed two new methodologies, that when combined allow to increase the precision whereas reducing the error, even on transient velocities. The two methodologies Variable Acquisition Window and a Quadrature Phase Compensation are addressed and combined simultaneously. A real implementation of the proposed algorithms is performed on a real hardware, with a DC motor and a low resolution encoder based on hall effect. The results validate the proposed approach since the errors are reduced compared with the standard Quadrature Encoder Reading.This work has been supported by FCT - Fundac¸ao˜ para a Ciencia e Tecnologia within the Project Scope: ˆ UIDB/05757/2020info:eu-repo/semantics/publishedVersio

    Hysteroscopy and pain: what risk factors should we consider in office hysteroscopy? are there really any?

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    Background: Office hysteroscopy is the gold standard in abnormal uterine bleeding and an indispensable tool in modern gynecology. It is becoming increasingly popular leading to examinations and even operations without anesthesia as it is accurate, cheap and well tolerated. However, pain is still a limitation. The objective of the study was to determine if pain perception is linked to clinical predictors and how well they correlate with pain score.Methods: Prospective observational trial enrolled one hundred and four women; four cases were excluded. One hundred cases were included and analyzed. Selection criteria: patients scheduled for Office Hysteroscopy who accepted to participate and had no contraindication for procedure.Results: A ten centimeter visual analogue scale was used for pain evaluation. Presumed variables such as menopause, pelvic pain, previous cesarean section and cervical surgery, and body mass index were analyzed by ordered regression using standard statistical software tools.Conclusions: Correlation between predictive factors and pain reporting showed no significance (p>0.05) except for body mass index which was found to significantly correlate to discomfort (p<0.05)

    ISO 9000/1994, ISO 9001/2000 and TQM: The performance debate revisited

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    The debate about the impact of ISO 9000/1994 on performance has been waging since its inception. While there is a general agreement regarding the positive impact of TQM on performance, there has been less agreement among the academics about the impact of ISO 9000/1994. Perhaps in response to such debate, the new ISO 9001/2000 has appeared purporting to be more in line with the TQM philosophy. As of now, how this 2000 version actually affects performance is yet to be explored. In this study, we compare the implementation of ISO 9000/1994 and ISO 9001/2000 as representing two different efforts to implement quality management practices. We evaluate its impact on company performance with a sample of 713 Spanish industrial companies. We also examine if the 2000 version of ISO is taking us closer to the implementation of TQM. Further, we depart from the past studies methodologically by considering performance as a formative construct rather than a reflective construct. Based on the mean and covariance structural (MACS) analyses, we conclude that ISO 9001/2000 certified companies do not perform noticeably better than ISO 9000/1994 or non-certified companies. However, we find that ISO 9001/2000 certified companies apply TQM at a higher level than ISO 9000/1994 certified companies, but whether they actually perform better is less clear.We would like to thank the Fundacio ́nSe ́neca andFundacio ́n Cajamurcia for financial support. We alsoacknowledge two anonymous referees and the associateeditor for valuable comments and insight

    Bayesian online learning for energy-aware resource orchestration in virtualized RANs

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    Proceedings of: IEEE International Conference on Computer Communications, 10-13 May 2021, Vancouver, BC, Canada.Radio Access Network Virtualization (vRAN) will spearhead the quest towards supple radio stacks that adapt to heterogeneous infrastructure: from energy-constrained platforms deploying cells-on-wheels (e.g., drones) or battery-powered cells to green edge clouds. We perform an in-depth experimental analysis of the energy consumption of virtualized Base Stations (vBSs) and render two conclusions: (i) characterizing performance and power consumption is intricate as it depends on human behavior such as network load or user mobility; and (ii) there are many control policies and some of them have non-linear and monotonic relations with power and throughput. Driven by our experimental insights, we argue that machine learning holds the key for vBS control. We formulate two problems and two algorithms: (i) BP-vRAN, which uses Bayesian online learning to balance performance and energy consumption, and (ii) SBP-vRAN, which augments our Bayesian optimization approach with safe controls that maximize performance while respecting hard power constraints. We show that our approaches are data-efficient and have provably performance, which is paramount for carrier-grade vRANs. We demonstrate the convergence and flexibility of our approach and assess its performance using an experimental prototype.This work was supported by the European Commission through Grant No. 856709 (5Growth) and Grant No. 101017109 (DAEMON); and by SFI through Grant No. SFI 17/CDA/4760
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