130,579 research outputs found
Catchment travel time distributions and water flow in soils
No full textMany details about the flow of water in soils in a hillslope are unknowable given current technologies. One way of learning about the bulk effects of water velocity distributions on hillslopes is through the use of tracers. However, this paper will demonstrate that the interpretation of tracer information needs to become more sophisticated. The paper reviews, and complements with mathematical arguments and specific examples, theory and practice of the distribution(s) of the times water particles injected through rainfall spend traveling through a catchment up to a control section (i.e., “catchment” travel times). The relevance of the work is perceived to lie in the importance of the characterization of travel time distributions as fundamental descriptors of catchment water storage, flow pathway heterogeneity, sources of water in a catchment, and the chemistry of water flows through the control section. The paper aims to correct some common misconceptions used in analyses of travel time distributions. In particular, it stresses the conceptual and practical differences between the travel time distribution conditional on a given injection time (needed for rainfall‐runoff transformations) and that conditional on a given sampling time at the outlet (as provided by isotopic dating techniques or tracer measurements), jointly with the differences of both with the residence time distributions of water particles in storage within the catchment at any time. These differences are defined precisely here, either through the results of different models or theoretically by using an extension of a classic theorem of dynamic controls. Specifically, we address different model results to highlight the features of travel times seen from different assumptions, in this case, exact solutions to a lumped model and numerical solutions of the 3‐D flow and transport equations in variably saturated, physically heterogeneous catchment domains. Our results stress the individual characters of the relevant distributions and their general nonstationarity yielding their legitimate interchange only in very particular conditions rarely achieved in the field. We also briefly discuss the impact of oversimple assumptions commonly used in analyses of tracer data
Gravitational tests of electroweak relaxation
No full textAbstract We consider a scenario in which the electroweak scale is stabilized via the relaxion mechanism during inflation, focussing on the case in which the back-reaction potential is generated by the confinement of new strongly interacting vector-like fermions. If the reheating temperature is sufficiently high to cause the deconfinement of the new strong interactions, the back-reaction barrier then disappears and the Universe undergoes a second relaxation phase. This phase stops when the temperature drops sufficiently for the back-reaction to form again. We identify the regions of parameter space in which the second relaxation phase does not spoil the successful stabilization of the electroweak scale. In addition, the generation of the back-reaction potential that ends the second relaxation phase can be associated to a strong first order phase transition. We then study when such transition can generate a gravitational wave signal in the range of detectability of future interferometer experiments
The see-saw portal at future Higgs Factories
No full textWe consider an extension of the Standard Model with two right-handed singlet fermions with mass at the electroweak scale that induce neutrino masses, plus a generic new physics sector at a higher scale Λ. We focus on the effective operators of lowest dimension d = 5, which induce new production and decay modes for the singlet fermions. We assess the sensitivity of future Higgs Factories, such as FCC-ee, CLIC-380, ILC and CEPC, to the coefficients of these operators for various center of mass energies. We show that future lepton colliders can test the cut-off of the theory up to Λ ≃ 500–1000 TeV, surpassing the reach of future indirect measurements of the Higgs and Z boson widths. We also comment on the possibility of determining the underlying model flavor structure should a New Physics signal be observed, and on the impact of higher dimensional d = 6 operators on the experimental signatures
Peritoneal seeding from appendiceal carcinoma: A case report and review of the literature
No full textNon-carcinoid appendiceal malignancies are rare entities, representing less than 0.5% of all gastrointestinal malignancies. Because of their rarity and particular biological behavior, a substantial number of patients affected by these neoplasms do not receive appropriate surgical resection. In this report, we describe a rare case of primary signet-ring cell carcinoma of the appendix with peritoneal seeding which occurred in a 40-year old man admitted at the Emergency Surgery Department with the clinical suspicion of acute appendicitis. After a surgical debulking and right hemicolectomy, the patient had systemic chemotherapy according to FOLFOX protocol. After completion of the latter, the patient underwent cytoreductive surgery plus hyperthermic intraperitoneal chemotherapy. This report offers a brief review of the literature and suggests an algorithm for the management of non-carcinoid appendiceal tumors with peritoneal dissemination
Dark photon bounds in the dark EFT
No full textDark photons are massive abelian gauge bosons that interact with ordinary photons via a kinetic mixing with the hypercharge field strength tensor. This theory is probed by a variety of different experiments and limits are set on a combination of the dark photon mass and kinetic mixing parameter. These limits can however be strongly modified by the presence of additional heavy degrees of freedom. Using the framework of dark effective field theory, we study how robust are the current experimental bounds when these new states are present. We focus in particular on the possible existence of a dark dipole interaction between the Standard Model leptons and the dark photon. We show that, under certain assumptions, the presence of a dark dipole modifies existing supernovæ bounds for cut-off scales up to O(10–100 TeV). On the other hand, terrestrial experiments, such as LSND and E137, can probe cut-off scales up to O(3 TeV). For the latter experiment we highlight that the bound may extend down to vanishing kinetic mixing
The see-saw portal at future Higgs factories: the role of dimension six operators
No full textWe study an extension of the Standard Model with electroweak scale
right-handed singlet fermions that induces neutrino masses, plus a generic
new physics sector at a higher scale . The latter is parametrized in
terms of effective operators in the language of the SMEFT. We study its
phenomenology considering operators up to , where additional production
and decay modes for are present in addition to those arising from the
mixing with the active neutrinos. We focus on the production with four-Fermi
operators and we identify the most relevant additional decay modes to be and . We assess the sensitivity of future Higgs factories
on the SMEFT in regions of the parameter space where the new states decay
promptly, displaced or are stable on detector lengths. We show that new physics
scale up to TeV can be explored, depending on the collider considered.Comment: 30 pages, 8 figures. v2: section with theoretical bounds added,
matches version accepted for publication in JHE
Sensor-based localization of epidemic sources on human mobility networks.
No full textWe investigate the source detection problem in epidemiology, which is one of the most important issues for control of epidemics. Mathematically, we reformulate the problem as one of identifying the relevant component in a multivariate Gaussian mixture model. Focusing on the study of cholera and diseases with similar modes of transmission, we calibrate the parameters of our mixture model using human mobility networks within a stochastic, spatially explicit epidemiological model for waterborne disease. Furthermore, we adopt a Bayesian perspective, so that prior information on source location can be incorporated (e.g., reflecting the impact of local conditions). Posterior-based inference is performed, which permits estimates in the form of either individual locations or regions. Importantly, our estimator only requires first-arrival times of the epidemic by putative observers, typically located only at a small proportion of nodes. The proposed method is demonstrated within the context of the 2000-2002 cholera outbreak in the KwaZulu-Natal province of South Africa
Can the new resonance at LHC be a CP-odd Higgs boson?
No full textAbstractA plausible explanation of the recent experimental indication of a resonance in the two-photon spectrum at LHC is that it corresponds to the CP-odd Higgs boson. We explore such a possibility in a generic framework of the two Higgs doublet models (2HDM), and combine mA≈750 GeV with the known mh=125.7(4) GeV to show that the charged Higgs boson and the other CP-even scalar masses become bounded from bellow and from above. We show that this possibility is also consistent with the electroweak precision data and the low energy observables, which we test in a few leptonic and semileptonic decay modes
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