159 research outputs found

    Composite Scalar Dark Matter

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    We show that the dark matter (DM) could be a light composite scalar η\eta, emerging from a TeV-scale strongly-coupled sector as a pseudo Nambu-Goldstone boson (pNGB). Such state arises naturally in scenarios where the Higgs is also a composite pNGB, as in O(6)/O(5)O(6)/O(5) models, which are particularly predictive, since the low-energy interactions of η\eta are determined by symmetry considerations. We identify the region of parameters where η\eta has the required DM relic density, satisfying at the same time the constraints from Higgs searches at the LHC, as well as DM direct searches. Compositeness, in addition to justify the lightness of the scalars, can enhance the DM scattering rates and lead to an excellent discovery prospect for the near future. For a Higgs mass mh≃125m_h\simeq 125 GeV and a pNGB characteristic scale f≲1f \lesssim 1 TeV, we find that the DM mass is either mη≃50−70m_\eta \simeq 50-70 GeV, with DM annihilations driven by the Higgs resonance, or in the range 100-500 GeV, where the DM derivative interaction with the Higgs becomes dominant. In the former case the invisible Higgs decay to two DM particles could weaken the LHC Higgs signal.Comment: 19 pages + appendices, 16 figures. v2: minor changes. v3: version published in JHE

    The use of silicon-germanium superlattices for thermoelectric devices and microfabricated generators

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    Low dimensional structures such as superlattices have the potential to improve the thermoelectric properties of materials by engineering the scattering of phonons to reduce the thermal conductivity and therefore improve the thermeoelectric performance. Here we demonstrate the reduction in thermal conductivity in Ge/SiGe superlattices using multiple barrier engineering to scatter acoustic phonons at the key wavelengths for thermal transport. The approach allows ZT to be increased in wide quantum well superlattices through the reduction of heterointerfaces which scatter both electrons and phonons

    Nutrizione e ritmo circadiano: la nuova prospettiva del Time Restricted Feeding

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    SommarioNegli ultimi anni il digiuno intermittente è emerso quale approccio innovativo per promuovere il calo ponderale e migliorare lo stato di salute metabolica in contrapposizione agli interventi più convenzionali incentrati sulla restrizione calorica. Il digiuno intermittente (Intermittent Fasting) e il Time-Restricted Feeding (TRF) negli animali (anche noto come Time-Restricted Eating, TRE nell'uomo) hanno raggiunto una crescente popolarità parallelamente al consistente aumento delle evidenze scientifiche nell'ambito della cronobiologia, con la recente attribuzione del premio Nobel per la Medicina nel 2017 a Jeffrey C. Hall, Michael Rosbash e Michael W. Young quale riconoscimento per il contributo alle scoperte dei meccanismi molecolari che sottendono il ritmo circadiano. Il sistema circadiano regola il metabolismo in un ciclo di circa ventiquattro ore, determinando una ritmicità circadiana endogena nel dispendio energetico, nell'appetito, nella sensibilità insulinica e in altri processi metabolici. Molti di tali processi, tra cui la sensibilità insulinica e la termogenesi indotta dalla dieta, presentano un picco nella prima parte della giornata. Numerose evidenze sia nell'animale sia nell'uomo sottolineano che alimentarsi in momenti della giornata che siano asincroni rispetto ai ritmi delle suddette funzioni metaboliche promuova l'eccesso ponderale e le alterazioni metaboliche ad esso associate

    L'assorbimetria a raggi X a doppia energia: oltre l'osso c'è di più

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    SommarioAlla base dell'attuale epidemia di obesità (globesity) la sedentarietà occupa un posto di primo ordine: non solo perché mantiene l'eccesso di tessuto adiposo, ma perché predispone il soggetto obeso all'erosione della massa muscolare scheletrica (sarcopenia) e del patrimonio minerale osseo (osteopenia/osteoporosi). In questo scenario si inserisce la DXA che, a fronte di un costo biologico e tempi di esecuzione minimi, nella versione total-body fornisce una fotografia attendibile e dettagliata della composizione corporea (si pensi alla massa magra appendicolare o al tessuto adiposo viscerale). Dettagli che però sono essenziali proprio per le diagnosi di sarcopenia e obesità

    Outcomes of Laparoscopic Surgery for Colorectal Cancer in Elderly Patients

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    Laparoscopic colorectal surgery appears to be feasible and safe in elderly patients with increased comorbidity

    The role of neighborhood inequalities on diabetes prevention care: a mini-review

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    An emerging research niche has focused on the link between social determinants of health and diabetes mellitus, one of the most prevalent non-communicable diseases in modern society. The aim of the present mini-review is to explore and summarize current findings in this field targeting high-income countries. In the presence of disadvantaged neighborhood factors (including socioeconomic status, food environment, walkability and neighborhood aesthetics), diabetes prevention and care are affected at a multidimensional level. The vast majority of the included studies suggest that, besides individual risk factors, aggregated neighborhood inequalities should be tackled to implement effective evidence-based policies for diabetes mellitus

    Neopterin levels are independently associated with cardiac remodeling in patients with chronic heart failure

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    Neopterin, a marker of inflammation and monocyte activation, is found increased in patients with heart failure (HF). This study investigates whether neopterin levels correlate with left ventricular (LV) remodeling and brain natriuretic peptide (BNP), a marker of cardiac stress, in chronic HF (CHF) patients with different severity of disease. The relationship between elevated neopterin levels and LV enlargement in CHF patients suggests a crucial role of monocyte activation in the development of cardiac dysfunction in CHF patients. Assessment of neopterin levels is a potential biomarker to evaluate the progression of LV remodeling in CHF patients

    Low scale gravity as the source of neutrino masses?

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    We address the question whether low-scale gravity alone can generate the neutrino mass matrix needed to accommodate the observed phenomenology. In low-scale gravity the neutrino mass matrix in the flavor basis is characterized by one parameter (the gravity scale M_X) and by an exact or approximate flavor blindness (namely, all elements of the mass matrix are of comparable size). Neutrino masses and mixings are consistent with the observational data for certain values of the matrix elements, but only when the spectrum of mass is inverted or degenerate. For the latter type of spectra the parameter M_{ee} probed in double beta experiments and the mass parameter probed by cosmology are close to existing upper limits.Comment: 10 pages, 1 figur

    New advances in metabolic syndrome, from prevention to treatment. The role of diet and food

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    The definition of metabolic syndrome (MetS) has undergone several changes over the years due to the difficulty in establishing universal criteria for it. Underlying the disorders related to MetS is almost invariably a pro-inflammatory state related to altered glucose metabolism, which could lead to elevated cardiovascular risk. Indeed, the complications closely related to MetS are cardiovascular diseases (CVDs) and type 2 diabetes (T2D). It has been observed that the predisposition to metabolic syndrome is modulated by complex interactions between human microbiota, genetic factors, and diet. This review provides a summary of the last decade of literature related to three principal aspects of MetS: (i) the syndrome’s definition and classification, pathophysiology, and treatment approaches; (ii) prediction and diagnosis underlying the biomarkers identified by means of advanced methodologies (NMR, LC/GC-MS, and LC, LC-MS); and (iii) the role of foods and food components in prevention and/or treatment of MetS, demonstrating a possible role of specific foods intake in the development of MetS
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