460 research outputs found

    Axions and Anomaly-Mediated Interactions: The Green-Schwarz and Wess-Zumino Vertices at Higher Orders and g-2 of the muon

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    We present a study of the mechanism of anomaly cancellation using only transverse invariant amplitudes on anomaly diagrams at higher perturbative orders. The method is the realization of the Green-Schwarz (GS) mechanism at field theory level, which restores the Ward identities by a subtraction of the anomaly pole. Some of the properties of the GS vertex are analyzed both in the context of unitarity and of the organization of the related perturbative expansion. We investigate the role played by the GS and the Wess-Zumino vertices in the anomalous magnetic moment of the muon and in the hyperfine splitting of muonium, which are processes that can be accompanied by the exchange of a virtual anomalous extra Z-prime and an axion-like particle.Comment: 51 Pages, 31 Figures, Revised final version to appear on JHE

    Felid Cardiopulmonary Nematodes: Dilemmas Solved and New Questions Posed

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    In the past decade cardiopulmonary nematodes affecting felids have become a core research topic in small animal parasitology. In the late 2000s, an increase in studies was followed by unexpected findings in the early 2010s, which have stimulated research teams to start investigating these intriguing parasites. Prolific scientific debate and exchanges have then fostered field and laboratory studies and epi-zootiological surveys. New data have improved basic and applied knowledge, solved dilemmas and posed new questions. This article discusses the past and present background to felid cardiopulmonary nematodes after the last few years of intense scientific research. New data which have demonstrated the key role of Aelurostrongylus abstrusus and Troglostrongylus brevior in causing respiratory infections in domestic cats, and on the nil to negligible current importance of other species, i.e., Troglostrongylus subcrenatus, Oslerus rostratus and Angiostrongylus chabaudi, are presented. Biological information and hypothesized alternative routes of infection are analysed and discussed. Novel identification and taxonomical data and issues are reported and commented upon. On the whole, recent biological, ecological and epi-zootiological information on felid meta-strongyloids is critically analysed, with the aim to answer outstanding questions, stimulate future studies, and underline new research perspectives

    Seismic Anisotropy Analysis in the Victoria Land Region (Antarctica)

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    We present shear-wave splitting results obtained from analysis of core refracted teleseismic phases recorded by permanent and temporary seismographic stations located in the Victoria Land region (Antarctica). We used eigenvalue technique to linearize the rotated and shifted shear-wave particle motion, in order to determine the best splitting parameters. A well-scattered distribution of single shear-wave measurements has been obtained. Average values show clearly that dominant fast axis direction is NE-SW oriented, accordingly with previous measurements obtained around this zone. Only two stations, OHG and STAR show different orientations, with N-S and NNWSSE main directions. On the basis of the periodicity of single shear-wave splitting measurements with respect to back-azimuths of events under study, we inferred the presence of lateral and vertical changes in the deep anisotropy direction. To test this hypothesis we have modelling waveforms using a cross-convolution technique in one and two anisotropic layer’s cases. We obtained a significant improvement on the misfit in the double layer case for the cited couple of stations. For stations where a multi-layer structure does not fit, we looked for evidences of lateral anisotropy changes at depth through Fresnel zone computation. As expected, we find that anisotropy beneath the Transantarctic Mountains (TAM) is considerably different from that beneath the Ross Sea. This feature influences the measurement distribution for the two permanent stations TNV and VNDA. Our results show a dominant NESW direction over the entire region, but other anisotropy directions are present and find an interpretation when examined in the context of regional tectonics

    Additive Manufacturing of Poly(Methyl Methacrylate) Biomedical Implants with Dual-Scale Porosity

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    The development of bone permanent implants with a porous structure favoring their integration with the surrounding tissues is emerging as an attractive field of application of additive manufacturing (AM). This article reports on the investigation of the suitability of a hybrid AM technique, that is, computer-aided wet-spinning (CAWS), to fabricate novel poly(methyl meth- acrylate) (PMMA) constructs as porous implant prototypes. The optimization of the processing parameters to fabricate PMMA samples with a predefined internal porous structure and different external shapes is described. The study demonstrates that tailoring post-processing conditions represents a powerful tool to optimize samples macroscopic aspect, micromorphology, and mechanical properties. In particular, the possibility of obtaining a dual-scale porosity through the integration of the macroporous structure determined by the material lay-down pattern with a submicrometric porosity resulting from the phase inversion process governing polymer solidification, together with the possibility of purifying the employed commercial material from residual monomer during coagulation in ethanol, are reported as note- worthy advantages of CAWS over other AM techniques. A natural progression of this work is the development of relevant complex anatomical prototypes with tailored porosity by processing digital data obtained from computer tomography imaging of bone defects

    Hepatic abscess caused by trans-gastric migration of a fishbone

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    Background Stomach or duodenal perforation due to foreign body are usually associated with the development of a walled-off abdominal mass or abscess, and are less prone to cause systemic signs of infection. Methods and Case presentation A 65-year-old man with no comorbidities was admitted for rapid onset of abdominal discomfort, fever, and chills. An abdominal computed tomography (CT) showed an 8 cm abscess in the left lobe of the liver. The lesion was aspirated under ultrasound guidance; cultures from the abscess grew Streptococcus constellatus. Chest CT scan, colonoscopy, esophagogastroduodenoscopy, and blood cultures were negative. The patient’s clinical status rapidly improved with antibiotic therapy, but a follow-up CT scan revealed the presence of a thin, 3 cm-long radiopaque object at the site of the previous abscess. A few months later, due to symptomatic cholelithiasis, the patient underwent elective laparoscopic cholecystectomy and concurrent removal of a 3 cm-long fishbone, which was embedded into the wall of the gastric antrum and the third segment of the liver, the latter which was partially resected. Results The small gastrotomy was reapproximated with a single resorbable stitch. The post-operative course was uneventful and at 6 month follow up, the patient was asymptomatic without evidence of residual abdominal pathology. Conclusions Asymptomatic perforation of the gastric wall by an ingested foreign body can occur and be subsequently complicated by a liver abscess. A contained perforation can be successfully managed conservatively

    A Light Supersymmetric Axion in an Anomalous Abelian Extension of the Standard Model

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    We present a supersymmetric extension of the Standard Model (USSM-A) with an anomalous U(1) and Stueckelberg axions for anomaly cancellation, generalizing similar non-supersymmetric constructions. The model, built by a bottom-up approach, is expected to capture the low-energy supersymmetric description of axionic symmetries in theories with gauged anomalous abelian interactions, previously explored in the non-supersymmetric case for scenarios with intersecting branes. The choice of a USSM-like superpotential, with one extra singlet superfield and an extra abelian symmetry, allows a physical axion-like particle in the spectrum. We describe some general features of this construction and in particular the modification of the dark-matter sector which involves both the axion and several neutralinos with an axino component. The axion is expected to be very light in the absence of phases in the superpotential but could acquire a mass which can also be in the few GeV range or larger. In particular, the gauging of the anomalous symmetry allows independent mass/coupling interaction to the gauge fields of this particle, a feature which is absent in traditional (invisible) axion models. We comment on the general implications of our study for the signature of moduli from string theory due to the presence of these anomalous symmetries.Comment: 46 pages, 28 figures. Revised version, accepted for a publication on Phys.Rev.

    Stuckelberg Axions and the Effective Action of Anomalous Abelian Models 1. A unitarity analysis of the Higgs-axion mixing

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    We analyze the quantum consistency of anomalous abelian models and of their effective field theories, rendered anomaly-free by a Wess-Zumino term, in the case of multiple abelian symmetries. These models involve the combined Higgs-Stuckelberg mechanism and predict a pseudoscalar axion-like field that mixes with the goldstones of the ordinary Higgs sector. We focus our study on the issue of unitarity of these models both before and after spontaneous symmetry breaking and detail the set of Ward identities and the organization of the loop expansion in the effective theory. The analysis is performed on simple models where we show, in general, the emergence of new effective vertices determined by certain anomalous interactions.Comment: 67 pages, 26 figures, replaced with revised final version, to appear on JHE

    Potential role of Hepatozoon canis in a fatal systemic disease in a puppy

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    Canine hepatozoonosis caused by Hepatozoon canis is an emerging disease in Europe. Clinical pictures vary from subclinical to life-threatening and non-specific clinical signs are predominantly reported. A 2-month-old female puppy originating from Southern Italy was adopted and moved to Northern Italy. Then, the dog was brought to a local veterinary practice for gastrointestinal signs, migrating lameness and pruritic dermatitis, and then tested positive for Hepatozoon spp. gamonts at the blood smear. After treatment with imidocarb dipropionate and doxycycline, the dog showed an initial clinical improvement. However, gastrointestinal signs recurred, and diffuse superficial pyoderma appeared on the thoracolumbar region, along with fever, lethargy, and weight loss. Eight months from the first onset of clinical signs, the dog was referred to a veterinary clinic and subjected to complete blood count, urine and fecal analysis, along with abdominal ultrasonography, whole-body CT and gastroduodenal endoscopy. Skin biopsies and blood samples were subjected to a PCR-coupled sequencing protocol, which scored both positive for H. canis. Alterations were consistent with a pre-existing cholangiohepatitis and multiple acquired extrahepatic shunts secondary to portal hypertension. The dog was euthanatized due to a clinical worsening two months later. The potential role of H. canis in the systemic disease observed, clinic-pathological findings and epizootiological implications are discusse

    Assessment of the Feasibility of an Extended Range Helicopter Operational Standard for Offshore Flights

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    The accident rate of rotorcraft has improved signi1cantly over the years but at a slow pace, and in any case the number of accidents per 2ight hours is one or two orders of magnitude higher than that of commercial aircraft, a consideration that could be reasonably related to the inherent higher risk associate with rotorcraft operations. This represent a strong evidence of the necessity to introduce airworthiness operation standards also in the rotorcraft community, as an effective mean to improve safety records, borrowing from the experience done in the commercial air transport community with the introduction of ETOPS. In this paper, a 1rst proposal of development of a safety standard for helicopter offshore operation is discussed together with the possible support to this development that could be given by the EU H2020 project NITROS

    Fatal Pulmonary Hypertension and Right-Sided Congestive Heart Failure in a Kitten Infected with Aelurostrongylus abstrusus

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    Aelurostrongylus abstrusus is considered the most important respiratory nematode of domestic cats worldwide. This parasite inhabits the alveoli, alveolar ducts, and bronchioles and causes a subacute to chronic respiratory clinical disease. Clinical signs may occur in domestic cats of any age, though they are more often described in young animals. Physical examination, echocardiography, thoracic radiography, pulmonary and cardiac pathological findings, classical, and molecular parasitological analysis of a six-month-old kitten referred at the Veterinary Teaching Hospital of the University of Pisa (Italy) led to a diagnosis of parasitic bronchopneumonia caused by A. abstrusus, which was complicated by severe pulmonary hypertension (PH) and right-sided congestive heart failure (R-CHF) that caused the death of the animal. Cases of reversible PH associated with A. abstrusus infection have been seldom reported in cats. This is the first report of fatal PH and R-CHF in a kitten with clinical aelurostrongylosis
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