Lp-cohomology of negatively curved manifolds

We compute the $L^p$-cohomology spaces of some negatively curved manifolds. We deal with two cases: manifolds with finite volume and sufficiently pinched negative curvature, and conformally compact manifolds

Preroughening, Diffusion, and Growth of An FCC(111) Surface

Preroughening of close-packed fcc(111) surfaces, found in rare gas solids, is an interesting, but poorly characterized phase transition. We introduce a restricted solid-on-solid model, named FCSOS, which describes it. Using mostly Monte Carlo, we study both statics, including critical behavior and scattering properties, and dynamics, including surface diffusion and growth. In antiphase scattering, it is shown that preroughening will generally show up at most as a dip. Surface growth is predicted to be continuous at preroughening, where surface self-diffusion should also drop. The physical mechanism leading to preroughening on rare gas surfaces is analysed, and identified in the step-step elastic repulsion.Comment: Revtex + uuencoded figures, to appear in Physical Review Letter

Synthesis, crystal structure, structural phase transition and dielectric properties of new organic-inorganic hybrid compound: (C6H5CH2N(C2H5)3)CdCl3

Single crystal of new organic-inorganic hybrid compound, (C6H5CH2N(C2H5)3)CdCl3, was successfully synthesis by slow evaporation method at room temperature and characterized by divers techniques such as single X-ray diffraction, Infrared and Raman spectroscopy, Thermal analysis (TGA and DSC), Variable temperature X-ray powder diffraction (VT‒XRPD) and dielectric properties. The results of single X-ray studies demonstrated that the title compound crystallizes in the monoclinic system with the space group P21/n. The atomic arrangement of the crystal structure can be described as 1D polymeric inorganic chain CdCl5 along the a-axis between which the organic groups are located. It consists on isolated square-pyramidal [CdCl5]3− anions and triethylbenzylammonuim (C6H5CH2N(C2H5)3)+ cations, which are interconnected via C−H…Cl weak hydrogen bonds forming 3D network. Investigation of RT‒XRPD was carried out to identify the purity of the bulk material. Hirshfeld surface and fingerprint plots reveal that the structure is dominated by H…H and H…Cl/Cl…H contacts. It is found that the (C6H5CH2N(C2H5)3)CdCl3 material displays a irreversible structural phase transition at T = 413 K. This latter was confirmed by means of variable temperature X- ray powder diffraction and dielectric permittivity (ε′andε′)

Mechanochemical Preparation of Dipyridyl-Naphthalenediimide Cocrystals: Relative Role of Halogen-Bond and π-πInteractions

Naphthalenediimide derivates are a class of π-conjugated molecules largely investigated in the literature and used as building blocks for metal-organic frameworks or coformers for hydrogen-bond-based cocrystals. However, their tendency to establish halogen-bond interactions remains unexplored. By using a crystalline engineering approach, we report here four new cocrystals with N,N′-di(4-pyrydyl)-naphthalene-1,4,5,8-tetracarboxidiimide and diiodo-substituted coformers, easily obtained via a mechanochemical protocol. Cocrystals were characterized via NMR, electron ionization mass spectrometry, thermogravimetric analysis, powder X-ray diffraction, and single-crystal X-ray diffraction. Crystallographic structures were then finely examined and correlated with energy framework calculations to understand the relative contribution of halogen-bond and π-πinteractions toward framework stabilization

Hodge theory on Cheeger spaces

We extend the study of the de Rham operator with ideal boundary conditions from the case of isolated conic singularities, as analyzed by Cheeger, to the case of arbitrary stratified pseudomanifolds. We introduce a class of ideal boundary operators and the notion of mezzoperversity, which intermediates between the standard lower and upper middle perversities in intersection theory, as interpreted in this de Rham setting, and show that the de Rham operator with these boundary conditions is Fredholm and has compact resolvent. We also prove an isomorphism between the resulting Hodge and L2 de Rham cohomology groups, and that these are independent of the choice of iterated edge metric. On spaces which admit ideal boundary conditions of this type which are also self-dual, which we call ‘Cheeger spaces’, we show that these Hodge/de Rham cohomology groups satisfy Poincare' Duality

Energy Independence of a Small Office Community Powered by Photovoltaic-Wind Hybrid Systems in Widely Different Climates

Hybrid renewable energy systems are an optimal solution for small energy communities’ energy supply. One of the critical issues is the strong correlation of these systems with outdoor climatic conditions. The goal is to make local communities increasingly energy independent. To this end, an in-depth analysis of the behaviour of hybrid photovoltaic (PV)–wind systems powering small office communities in 48 locations around the world characterized by widely varying climates was conducted. System sizes, assumed to be stand-alone or grid-connected, were varied, for a total of 343 system power configurations. Highest satisfied load fraction (SLF) values are obtained with a significant predominance of PV over wind; the trend is more pronounced in dry and continental climates (zones B and D according to the Köppen climate classification). The utilization factor (UF) values of 1 are rarely reached and never in the wind-only or PV-only configurations. In all climates, the grid energy interaction factor (GEIF) values of zero are never reached but come very close. The benefit-cost ratio (BCR) of grid-connected systems is significantly higher than stand-alone systems

Facing the blockchain endpoint vulnerability, an SGX-based solution for secure eHealth auditing

According to McAfee Labs, even in 2019, the eHealth sector is confirmed as one of the most critical in terms of cybersecurity incidents. It is estimated that more than 176 million patient records were target of attacks between 2009 and 2017, and with a single attack, in 2018, more than 1.4 million patient records were affected at UnityPoint Health. To cope with such a dramatic situation, one of the main strategic priority in the eHealth field is represented by the adoption of Blockchain. Specifically, according to a Deloittes survey, 55% of healthcare executives believe that blockchain technology will disrupt the healthcare industry. Unfortunately, while blockchain provides a valuable tool for enhancing the security of health applications and related data, it cannot be assumed as a panacea for data security. As an example, the so-called Endpoint Vulnerability issue is a well-known problem of Blockchain-based solutions: in such a case the attacker successful in gaining control of the end-point can tamper data off-chain during its generation and/or before it is sent to the chain. In this paper, we face such an issue by shielding the endpoint through the Intel Software Guard eXtension (SGX) technology. We demonstrate our solution for an auditing software belonging to the European eHealth management system (namely OpenNCP). We also discuss how our solution can be generalized to any other Blockchain-based solution. Finally, an experimental evaluation has been conducted to prove the actual feasibility of the proposed solution under the requirements of the real eHealth system

Role of Estrogen and Estrogen Receptor in GH-Secreting Adenomas

Acromegaly is a rare disease with several systemic complications that may lead to increased overall morbidity and mortality. Despite several available treatments, ranging from transsphenoidal resection of GH-producing adenomas to different medical therapies, complete hormonal control is not achieved in some cases. Some decades ago, estrogens were first used to treat acromegaly, resulting in a significant decrease in IGF1 levels. However, due to the consequent side effects of the high dose utilized, this treatment was later abandoned. The evidence that estrogens are able to blunt GH activity also derives from the evidence that women with GH deficiency taking oral estro-progestins pills need higher doses of GH replacement therapy. In recent years, the role of estrogens and Selective Estrogens Receptor Modulators (SERMs) in acromegaly treatment has been re-evaluated, especially considering poor control of the disease under first- and second-line medical treatment. In this review, we analyze the state of the art concerning the impact of estrogen and SERMs on the GH/IGF1 axis, focusing on molecular pathways and the possible implications for acromegaly treatment

The critical Ising lines of the d=2 Ashkin-Teller model

The universal critical point ratio $Q$ is exploited to determine positions of the critical Ising transition lines on the phase diagram of the Ashkin-Teller (AT) model on the square lattice. A leading-order expansion of the ratio $Q$ in the presence of a non-vanishing thermal field is found from finite-size scaling and the corresponding expression is fitted to the accurate perturbative transfer-matrix data calculations for the $L\times L$ square clusters with $L\leq 9$.Comment: RevTex, 4 pages, two figure

Convective condensation of R449a inside a smooth tube

The HVAC sector has started the phase-out of refrigerants characterized by high values of global warming potential and atmospheric lifetime. Drop-in replacement requires that the new, environmentally safe fluids also show comparable heat transfer performances. This work addresses R449a, a low GWP zeotropic mixture (components: R32, R125, R1234yf, R134a, mass fractions: 24.3%, 24.7%, 25.3%, 25.7%, respectively), suitable to replace both R404A and R507A. Experiments were carried out on condensation in horizontal smooth tubes (outer diameter: 9.52 mm, thickness: 0.3 mm). The range of operating conditions meets the standard for HVAC devices (operating pressure: 14.46 bar, bubble temperature: 30°C, temperature glide: approximately 5 K refrigerant mass flux ranging from 136 to 202 kg m−2 s−1, quality change -0.8 and -0.2, mean quality ranging from 0.2 to 0.8). The test section is the inner pipe in a tube-in-tube counter-flow heat exchanger, where the refrigerant is cooled by a demineralized water stream in the annulus. Both the pressure drop and the heat transfer coefficient were measured across a length of 1.3 m and 1.1 m, respectively