865 research outputs found
A procedure for the change point problem in parametric models based on phi-divergence test-statistics
This paper studies the change point problem for a general parametric,
univariate or multivariate family of distributions. An information theoretic
procedure is developed which is based on general divergence measures for
testing the hypothesis of the existence of a change. For comparing the accuracy
of the new test-statistic a simulation study is performed for the special case
of a univariate discrete model. Finally, the procedure proposed in this paper
is illustrated through a classical change-point example
Accurate masses and radii of normal stars: modern results and applications
This paper presents and discusses a critical compilation of accurate,
fundamental determinations of stellar masses and radii. We have identified 95
detached binary systems containing 190 stars (94 eclipsing systems, and alpha
Centauri) that satisfy our criterion that the mass and radius of both stars be
known to 3% or better. To these we add interstellar reddening, effective
temperature, metal abundance, rotational velocity and apsidal motion
determinations when available, and we compute a number of other physical
parameters, notably luminosity and distance. We discuss the use of this
information for testing models of stellar evolution. The amount and quality of
the data also allow us to analyse the tidal evolution of the systems in
considerable depth, testing prescriptions of rotational synchronisation and
orbital circularisation in greater detail than possible before. The new data
also enable us to derive empirical calibrations of M and R for single (post-)
main-sequence stars above 0.6 M(Sun). Simple, polynomial functions of T(eff),
log g and [Fe/H] yield M and R with errors of 6% and 3%, respectively.
Excellent agreement is found with independent determinations for host stars of
transiting extrasolar planets, and good agreement with determinations of M and
R from stellar models as constrained by trigonometric parallaxes and
spectroscopic values of T(eff) and [Fe/H]. Finally, we list a set of 23
interferometric binaries with masses known to better than 3%, but without
fundamental radius determinations (except alpha Aur). We discuss the prospects
for improving these and other stellar parameters in the near future.Comment: 56 pages including figures and tables. To appear in The Astronomy and
Astrophysics Review. Ascii versions of the tables will appear in the online
version of the articl
The systemic treatment of recurrent ovarian cancer revisited
Treatment approaches for relapsed ovarian cancer have evolved over the past decade from a calendar-based decision tree to a patient-oriented biologically driven algorithm. Nowadays, platinum-based chemotherapy should be offered to all patients with a reasonable chance of responding to this therapy. The treatment-free interval for platinum is only one of many factors affecting patients' eligibility for platinum re-treatment. Bevacizumab increases the response to chemotherapy irrespective of the cytotoxic regimen and can be valuable in patients with an urgent need for symptom relief (e.g. pleural effusion, ascites). For patients with recurrent high-grade ovarian cancer, which responds to platinum-based treatment, maintenance therapy with a poly(ADP-ribose) polymerase inhibitor can be offered, regardless of the BRCA mutation status. Here we review contemporary decision-making processes in the systemic treatment of relapsed ovarian cancer
Surface features, rotation and atmospheric variability of ultra cool dwarfs
Photometric I band light curves of 21 ultra cool M and L dwarfs are
presented. Variability with amplitudes of 0.01 to 0.055 magnitudes (RMS) with
typical timescales of an hour to several hours are discovered in half of these
objects. Periodic variability is discovered in a few cases, but interestingly
several variable objects show no significant periods, even though the
observations were almost certainly sensitive to the expected rotation periods.
It is argued that in these cases the variability is due to the evolution of the
surface features on timescales of a few hours. This is supported in the case of
2M1145 for which no common period is found in two separate light curves. It is
speculated that these features are photospheric dust clouds, with their
evolution possibly driven by rotation and turbulence. An alternative
possibility is magnetically-induced surface features. However, chromospheric
activity undergoes a sharp decrease between M7 and L1, whereas a greater
occurrence of variability is observed in objects later than M9, lending support
to the dust interpretation.Comment: To appear in "Ultracool Dwarf Stars" (Lecture Notes in Physics),
H.R.A. Jones, I. Steele (eds), Springer-Verlag, 2001. Also available from
http://www.mpia-hd.mpg.de/homes/calj/ultra.htm
Automated synthesis of transmission lines loaded with complementary split ring resonators (CSRRs) and open complementary split ring resonators (OCSRRs) through aggressive space mapping (ASM)
This paper is focused on the application of space mapping optimization to the automated synthesis of
transmission lines loaded with complementary split ring resonators (CSRRs) and open complementary split ring resonators (OCSRRs). These structures are of interest for the implementation of resonant-type metamaterial transmission lines and for the design of planar microwave circuits based on such complementary resonators. The paper presents a method to generate the layouts of CSRR- and
OCSRR-loaded microstrip lines from the elements of their equivalent circuit models. Using the so-called aggressive space mapping, a specific implementation that uses quasi-Newton type iteration, we have developed synthesis algorithms that are able to provide the topology of these CSRR and OCSRR-loaded lines in few steps. The most relevant aspect, however, is that this synthesis process is completely
automatic, i.e., it does not require any action from the designers, other than initiating the algorithm. Moreover, this technique can be translated to other electrically small planar elements described by lumped element equivalent circuit models.This work has been partially supported by MICIIN-Spain (Projects TEC2010-17512 METATRANSFER, TEC2010-21520-C04-01 AVANSAT, CONSOLIDER EMET CSD2008-00066, and Grant AP2008-04707), Generalitat de Catalunya (Project 2009SGR-421), and MITyC-Spain (Project TSI-020100-2010-169 METASINTESIS). Ferran Martin is in debt to ICREA for supporting his work through an ICREA Academia Award (calls 2008 and 2013).Selga, J.; Rodríguez Pérez, AM.; Orellana, M.; Boria Esbert, VE.; Martín, F. (2014). Automated synthesis of transmission lines loaded with complementary split ring resonators (CSRRs) and open complementary split ring resonators (OCSRRs) through aggressive space mapping (ASM). Applied Physics A. 117(2):557-565. https://doi.org/10.1007/s00339-014-8703-xS5575651172G.V. Eleftheriades, K.G. Balmain, Negative Refraction Metamaterials: Fundamental Principles and Applications (Wiley, New Jersey, 2005)C. Caloz, T. Itoh, Electromagnetic Metamaterials: Transmission Line Theory and Microwave Applications (Wiley, New Jersey, 2006)R. Marqués, F. Martín, M. Sorolla, Metamaterials with Negative Parameters: Theory, Design and Microwave Applications (Wiley, New Jersey, 2008)F. Martín, Artificial Transmission Lines for RF and Microwave Applications. (Wiley, New Jersey) (to be published)M.A. Antoniades, G.V. Eleftheriades, A broadband series power divider using zero-degree metamaterial phase shifting lines. IEEE Microw. Wirel. Compon. Lett. 15, 808–810 (2005)H. Okabe, C. Caloz, T. Itoh, A compact enhanced bandwidth hybrid ring using an artificial lumped element left handed transmission line section. IEEE Trans. Microw. Theory Tech. 52, 798–804 (2004)G. Sisó, J. Bonache, M. Gil, F. Martín, Application of resonant-type metamaterial transmission lines to the design of enhanced bandwidth components with compact dimensions. Microw. Opt. Technol. Lett. 50, 127–134 (2008)I.H. Lin, M. De Vincentis, C. Caloz, T. Itoh, Arbitrary dual-band components using composite right/left handed transmission lines. IEEE Trans. Microw. Theory Tech. 52, 1142–1149 (2004)A.C. Papanastasiou, G.E. Georghiou, G.V. Eleftheriades, A quad-band Wilkinson power divider using generalized NRI transmission lines. IEEE Microw. Wirel. Compon. Lett. 18, 521–523 (2008)M. Durán-Sindreu, G. Sisó, J. Bonache, F. Martín, Planar multi-band microwave components based on the generalized composite right/left handed transmission line concept. IEEE Trans. Microw. Theory Tech. 58(12), 3882–3891 (2010)J. Bonache, I. Gil, J. García-García, F. Martín, Novel microstrip band pass filters based on complementary split ring resonators. IEEE Trans. Microw. Theory Tech. 54, 265–271 (2006)M. Gil, J. Bonache, J. García-García, J. Martel, F. Martín, Composite right/left handed (CRLH) metamaterial transmission lines based on complementary split rings resonators (CSRRs) and their applications to very wide band and compact filter design. IEEE Trans. Microw. Theory Tech. 55, 1296–1304 (2007)S. Lim, C. Caloz, T. Itoh, Metamaterial-based electronically-controlled transmission line structure as a novel leaky-wave antenna with tunable angle and beamwidth. IEEE Trans. Microw. Theory Tech. 52(12), 2678–2690 (2004)G. Zamora, S. Zuffanelli, F. Paredes, F. Javier Herraiz-Martínez, F. Martín, J. Bonache, Fundamental mode leaky-wave-antenna (LWA) using slot line and split-ring-resonator (SRR) based metamaterials. IEEE Antennas Wirel. Propag. Lett. 12, 1424–1427 (2013)A.K. Iyer, G.V. Eleftheriades, Negative refractive index metamaterials supporting 2-D waves. in IEEE-MTT Int’l Microwave Symposium, vol 2, Seattle, WA, pp. 412–415 (2002)A.A. Oliner, A periodic-structure negative-refractive-index medium without resonant elements. In URSI Digest, IEEE-AP-S USNC/URSI National Radio Science Meeting, San Antonio, TX, pp. 41 (2002)C. Caloz, T. Itoh, Application of the transmission line theory of left-handed (LH) materials to the realization of a microstrip LH transmission line. in Proceedings of IEEE-AP-S USNC/URSI National Radio Science Meeting, vol 2, San Antonio, TX, pp. 412–415 (2002)F. Martín, F. Falcone, J. Bonache, R. Marqués, M. Sorolla, Split ring resonator based left handed coplanar waveguide. Appl. Phys. Lett. 83, 4652–4654 (2003)F. Falcone, T. Lopetegi, M.A.G. Laso, J.D. Baena, J. Bonache, R. Marqués, F. Martín, M. Sorolla (2004) Babinet principle applied to the design of metasurfaces and metamaterials. Phys. Rev. Lett. 93, paper 197401M. Durán-Sindreu, A. Vélez, F. Aznar, G. Sisó, J. Bonache, F. Martín, Application of open split ring resonators and open complementary split ring resonators to the synthesis of artificial transmission lines and microwave passive components. IEEE Trans. Microw. Theory Tech. 57, 3395–3403 (2009)A. Vélez, F. Aznar, M. Durán-Sindreu, J. Bonache, F. Martín, Stop-band and band-pass filters in coplanar waveguide technology implemented by means of electrically small metamaterial-inspired open resonators. IET Microw. Antennas Propag. 4, 712–716 (2004)J.D. Baena, J. Bonache, F. Martín, R. Marqués, F. Falcone, T. Lopetegi, M.A.G. Laso, J. García, I. Gil, M. Flores-Portillo, M. Sorolla, Equivalent circuit models for split ring resonators and complementary split rings resonators coupled to planar transmission lines. IEEE Trans. Microw. Theory Tech. 53, 1451–1461 (2005)M. Gil, J. Bonache, J. Selga, J. García-García, F. Martín, Broadband resonant type metamaterial transmission lines. IEEE Microw. Wirel. Compon. Lett. 17, 97–99 (2007)M. Durán-Sindreu, P. Vélez, J. Bonache, F. Martín, Broadband microwave filters based on open split ring resonators (OSRRs) and open complementary split ring resonators (OCSRRs): improved models and design optimization. Radioengineering 20, 775–783 (2011)P. Vélez, J. Naqui, M. Durán-Sindreu, J. Bonache, F. Martín, Broadband microstrip bandpass filter based on open complementary split ring resonators. Int. J. Antennas Propag. 2012, 6 (2012)J.W. Bandler, R.M. Biernacki, S.H. Chen, P.A. Grobelny, R.H. Hemmers, Space mapping technique for electromagnetic optimization. IEEE Trans. Microw. Theory Tech. 42, 2536–2544 (1994)J.W. Bandler, R.M. Biernacki, S.H. Chen, R.H. Hemmers, K. Madsen, Electromagnetic optimization exploiting aggressive space mapping. IEEE Trans. Microw. Theory Tech. 43, 2874–2882 (1995)J.W. Bandler, Q.S. Cheng, S.A. Dakroury, A.S. Mohamed, M.H. Bakr, K. Madsen, J. Søndergaard, Space mapping: the state of the art. IEEE Trans. Microw. Theory Tech. 52, 337–361 (2004)C.G. Broyden, A class of methods for solving nonlinear simultaneous equations. Math. Comput. 19(92), 577–593 (1965)J. Selga, A. Rodríguez, V.E. Boria, F. Martín, Synthesis of split rings based artificial transmission lines through a new two-step, fast converging, and robust aggressive space mapping (ASM) algorithm. IEEE Trans. Microw. Theory Tech. 61(6), 2295–2308 (2013)A. Velez, F. Aznar, J. Bonache, M.C. Velázquez-Ahumada, J. Martel, F. Martín, Open complementary split ring resonators (OCSRRs) and their application to wideband CPW band pass filters. IEEE Microw. Wirel. Compon. Lett. 19, 197–199 (2009)D.M. Bates, D.G. Watts, Nonlinear Regression Analysis and Its Applications (Wiley, New York, 1998
Stochastic Gravity: Theory and Applications
Whereas semiclassical gravity is based on the semiclassical Einstein equation
with sources given by the expectation value of the stress-energy tensor of
quantum fields, stochastic semiclassical gravity is based on the
Einstein-Langevin equation, which has in addition sources due to the noise
kernel.In the first part, we describe the fundamentals of this new theory via
two approaches: the axiomatic and the functional. In the second part, we
describe three applications of stochastic gravity theory. First, we consider
metric perturbations in a Minkowski spacetime: we compute the two-point
correlation functions for the linearized Einstein tensor and for the metric
perturbations. Second, we discuss structure formation from the stochastic
gravity viewpoint. Third, we discuss the backreaction of Hawking radiation in
the gravitational background of a quasi-static black hole.Comment: 75 pages, no figures, submitted to Living Reviews in Relativit
Genetic Analysis of the Individual Contribution to Virulence of the Type III Effector Inventory of Pseudomonas syringae pv. phaseolicola
Several reports have recently contributed to determine the effector inventory of the sequenced strain Pseudomonas syringae pv. phaseolicola (Pph) 1448a. However, the contribution to virulence of most of these effectors remains to be established. Genetic analysis of the contribution to virulence of individual P. syringae effectors has been traditionally hindered by the lack of phenotypes of the corresponding knockout mutants, largely attributed to a high degree of functional redundancy within their effector inventories. In support of this notion, effectors from Pseudomonas syringae pv. tomato (Pto) DC3000 have been classified into redundant effector groups (REGs), analysing virulence of polymutants in the model plant Nicotiana benthamiana. However, using competitive index (CI) as a virulence assay, we were able to establish the individual contribution of AvrPto1PtoDC3000 to Pto DC3000 virulence in tomato, its natural host, even though typically, contribution to virulence of AvrPto1 is only shown in strains also lacking AvrPtoB (also called HopAB2), a member of its REG. This report raised the possibility that even effectors targeting the same defence signalling pathway may have an individual contribution to virulence, and pointed out to CI assays as the means to establish such a contribution for individual effectors. In this work, we have analysed the individual contribution to virulence of the majority of previously uncharacterised Pph 1448a effectors, by monitoring the development of disease symptoms and determining the CI of single knockout mutants at different stages of growth within bean, its natural host. Despite their potential functional redundancy, we have found individual contributions to virulence for six out of the fifteen effectors analysed. In addition, we have analysed the functional relationships between effectors displaying individual contribution to virulence, highlighting the diversity that these relationships may present, and the interest of analysing their functions within the context of the infection
Plural valuation of nature for equity and sustainability: Insights from the Global South
Plural valuation is about eliciting the diverse values of nature articulated by different stakeholders in order to inform decision making and thus achieve more equitable and sustainable outcomes. We explore what approaches align with plural valuation on the ground, as well as how different social-ecological contexts play a role in translating plural valuation into decisions and outcomes. Based on a co-constructed analytical approach relying on empirical information from ten cases from the Global South, we find that plural valuation contributes to equitable and sustainable outcomes if the valuation process: 1) is based on participatory value elicitation approaches; 2) is framed with a clear action-oriented purpose; 3) provides space for marginalized stakeholders to articulate their values in ways that can be included in decisions; 4) is used as a tool to identify and help reconcile different cognitive models about human-nature relations; and 5) fosters open communication and collaboration among stakeholders. We also find that power asymmetries can hinder plural valuation. As interest and support for undertaking plural valuation grows, a deeper understanding is needed regarding how it can be adapted to different purposes, approaches, and social-ecological contexts in order to contribute to social equity and sustainability
TNF-alpha Is Required for the Attraction of Mesenchymal Precursors to White Adipose Tissue in Ob/ob Mice
Most adult tissues harbour a stem cell subpopulation (Mesenchymal Precursors or MPs) that represent a small proportion of the total cell number and have the potential to differentiate into several cell types within the mesenchymal lineage. In adipose tissue, adipocytes account for two-thirds of the total cell number. The remaining cells include blood and endothelial cells, along with adipocyte precursors (adipose MPs). Obesity is defined as an excess of body fat that frequently results in a significant impairment of health. The ob/ob mice bear a mutation in the ob gene that causes a deficiency in the hormone leptin and hence obesity. Here, we present evidence that ob/ob mice have a dramatic decrease in the resident MP pool of several tissues, including squeletal muscle, heart, lung and adipose tissue. Moreover, we show that that there is a migration of MP cells from distant organs, as well as homing of these cells to the adipose tissue mass of the ob/ob mice. We call this process adipotaxis. Once in the adipose tissue, migrant MPs undergoe adipose differentiation, giving rise to new differentiated adipocytes within the adipose mass. Finally, we provide evidence that adipotaxis is largely explained by the production of high levels of Tumor Necrosis Factor-alpha (TNF-α) within the ob/ob adipose tissue. The therapeutic implications for human obesity as well as for regenerative medicine are further discussed in this paper
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Symptoms predicting psychosocial impairment in bulimia nervosa
Purpose
The current study aimed to determine which particular eating disorder (ED) symptoms and related features, such as BMI and psychological distress, uniquely predict impairment in bulimia nervosa (BN).
Methods
Two hundred and twenty-two adults with BN completed questionnaires assessing ED symptoms, general psychological distress, and psychosocial impairment. Regression analyses were used to determine predictors which account for variance in impairment.
Results
Four variables emerged as significant predictors of psychosocial impairment: concerns with eating; concerns with weight and shape; dietary restraint; and general psychological distress.
Conclusions
Findings support previous work highlighting the importance of weight and shape concerns in determining ED-related impairment. Other ED symptoms, notably dietary restraint and concerns with eating, were also significant predictors as was psychological distress. Results suggest that cognitive aspects of EDs, in addition to psychological distress, may be more important determinants of impairment than behavioural symptoms, such as binge eating or purging
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