Refinement Types for Logical Frameworks and Their Interpretation as Proof Irrelevance

Refinement types sharpen systems of simple and dependent types by offering expressive means to more precisely classify well-typed terms. We present a system of refinement types for LF in the style of recent formulations where only canonical forms are well-typed. Both the usual LF rules and the rules for type refinements are bidirectional, leading to a straightforward proof of decidability of typechecking even in the presence of intersection types. Because we insist on canonical forms, structural rules for subtyping can now be derived rather than being assumed as primitive. We illustrate the expressive power of our system with examples and validate its design by demonstrating a precise correspondence with traditional presentations of subtyping. Proof irrelevance provides a mechanism for selectively hiding the identities of terms in type theories. We show that LF refinement types can be interpreted as predicates using proof irrelevance, establishing a uniform relationship between two previously studied concepts in type theory. The interpretation and its correctness proof are surprisingly complex, lending support to the claim that refinement types are a fundamental construct rather than just a convenient surface syntax for certain uses of proof irrelevance

The hERG1 potassium channel behaves as prognostic factor in gastric dysplasia endoscopic samples

Purpose: Gastric cancer (GC) is still a relevant health issue worldwide. The identification of prognostic factors for progression of gastric dysplasia (GD), the main pre-cancerous lesion of the intestinal-type GC, is hence mandatory.Patients and methods: A cohort of 83 GD endoscopic samples belonging to Italian subjects was collected. hERG1 expression was evaluated by immunohistochemistry and scored 0-3, depending on the percentage of stained cells. Expression data were analysed in conjunction with clinico-pathological and survival data.Results: hERG1 turned out to be expressed in 67.47% (56 out of 83) of the GD samples. hERG1 expression was higher in high-grade GD compared to low-grade GD (29 out of 39, 74.36% vs 27 out of 44, 61.36%), although the statistical significance was not reached (P=0.246). No association emerged between hERG1 expression and clinical features of the patients (age, gender, localization, H. pylori infection, gastritis and intestinal metaplasia). In a subset of cases for which sequential samples of gastric lesions (from GD to Early Gastric Cancer and Advanced Gastric Cancer) were available, hERG1 expression was maintained in all the steps of gastric carcinogenesis from GD onwards. A general trend to increased expression in advanced lesions was observed. hERG1 score had a statistically significant impact on both Progression-Free Survival (P=0.018) and Overall Survival (P=0.031). In particular, patients displaying a high hERG1 score have a shorter survival.Conclusion: hERG1 is aberrantly expressed in human GD samples and has an impact on both PFS and OS, hence representing a novel prognostic marker for progression of GD towards GC of the intestinal histotype. Once properly validated, hERG1 detection could be included in the clinical practice, during endoscopic surveillance protocols, for the management of GD at higher risk of progression, as already proposed for Barrett's oesophagus

Transient Photoinduced Absorption in Ultrathin As-grown Nanocrystalline Silicon Films

We have studied ultrafast carrier dynamics in nanocrystalline silicon films with thickness of a few nanometers where boundary-related states and quantum confinement play an important role. Transient non-degenerated photoinduced absorption measurements have been employed to investigate the effects of grain boundaries and quantum confinement on the relaxation dynamics of photogenerated carriers. An observed long initial rise of the photoinduced absorption for the thicker films agrees well with the existence of boundary-related states acting as fast traps. With decreasing the thickness of material, the relaxation dynamics become faster since the density of boundary-related states increases. Furthermore, probing with longer wavelengths we are able to time-resolve optical paths with faster relaxations. This fact is strongly correlated with probing in different points of the first Brillouin zone of the band structure of these materials

Dynamics in the Sesia HP terrane: Combined petrochronological and structural analysis

HP terranes dominated by continental crust represent the end result of a sequence of processes that operate at lithosphere scale, i.e. rifting, subduction/accretion, return flow/exhumation. To under\uacstand the dynamics of the subduction channel in complex terranes of this kind, the effects from each stage must be investigated separately, linking the observations and data from kilometers down to micrometer scale. This task recommends an integrative approach. Here we focus on the assembly of the Sesia Zone (SZ), a key element of the internal Western Alps. This terrane comprises two main polymetamorphic base\uacment units and thin trails of a cover sequence that includes post-Permian syn- to post-rift metasediments; the latter show no pre-Alpine metamorphic imprint. The tectonic scenario of Babist et al. (2006) recognizes five main phases in the Alpine structural evolution; their model helped us select areas for detailed structural work and sampling. Our first goal was to relate the early convergent structures (D1, D2) to the P-T evolution and to establish a robust time-frame for the HP-dynamics within and between the tectonic slices. Within the subduction/extrusion channel, problems addressed include the question of tectonic mixing, i.e. temporal and spatial scales of relative and absolute movement of the slices, and the conditions and timing of their final juxtaposition prior to the rapid exhumation of the Sesia Zone as a whole. Mono- and polymetamorphic sediments from different slices display unequivocal evidence of several HP-stages separated in time. Successive stages under eclogite facies conditions occurred between 86 \u2013 65 Ma, as shown by LA-ICP-MS and SHRIMP data on growth zones in accessory allanite, monazite, zircon, and titanite. By using mutual inclusions and overgrowth relationships, the age-data on allanite and monazite can be tied to the multistage evolution of an individual sample. For different rocks, these (over)growth stages can be related to D1- and D2-deformation when micro-, meso- and megastructural observations are combined. Thermobarometry indicates intermittant decompression by ~0.8 GPa between HP phases, hence pressure cycling (aka yo-yo tectonics, Rubatto et al., 2011). This tectonic mobility occurred prior to the final juxtaposition of slices and their exhumation, which involved at least two major deformation phases and lead to widespread retrogression at amphibolite to green-schist facies conditions. Our approach combining structural, petrological, and geochronological techniques yields some field-based constraints on the duration and rates of the dynamics within a subduction channel. It may be useful to compare these to insights from numerical models, provided the latter take into account the specific conditions of the plate convergence, which turns out to have been highly oblique in the present case

Patient-specific Instrumentation Affects Rotational Alignment of the Femoral Component in Total Knee Arthroplasty : A Prospective Randomized Controlled Trial

Objective: To evaluate whether patient-specific instrumentation (PSI) improve the accuracy of femoral component rotational alignment with respect to conventionally-implanted total knee arthroplasty (TKA). Methods: Twenty-four patients were randomized to receive a TKA implanted with PSI or conventional instrumentation. Implant orientation was compared on Computed Tomography (CT). Surgical time, recuts, and component size variations from planning were recorded. Preoperative and postoperative Oxford knee score and visual analogue scale were compared to assess clinical outcomes. Results: Femoral components implanted with patient-specific instrumentation were aligned with greater external rotation than those implanted with conventional instrumentation (P = 0.022). No significant differences were found in surgical times, number of recuts, and clinical outcomes. Surgeon modifications from the planned size were necessary in 58% of PSI cases. Conclusion: Femoral components implanted with PSI had greater external rotation than with conventional instrumentation. Surgeons must carefully evaluate component sizes when using PSI, both in planning and during surgery

Geological and Hydrogeological Characterization of Springs in a DSGSD Context (Rodoretto Valley – NW Italian Alps)

As continuous groundwater monitoring in the upper sector of Rodoretto Valley (Germanasca Valley, Italian Western Alps) is hampered by logistical problem of data collection during winter and spring months, the only tools currently available to derive hydrogeological information are non-continuous and non-long-term dataset of spring discharge (Q), temperature (T) and electrical conductivity (EC). In order to quantity aquifer groundwater reserve, available Q dataset of a small mountain spring (Spring 1 CB) was investigated by applying the analytical solutions developed by Boussinesq (J Math Pure Appl 10:5–78, 1904) and Maillet (Essais dı’hydraulique souterraine et fluviale, vol 1. Herman et Cie, Paris, 1905); T and EC datasets were also used to provide qualitative information about the nature of the aquifer that supplies the spring. The outcomes of the elaborations highlighted the limits of applicability of these methods in the presence of a non-continuous Q dataset: both Boussinesq (J Math Pure Appl 10:5–78, 1904) and Maillet (Essais dı’hydraulique souterraine et fluviale, vol 1. Herman et Cie, Paris, 1905) estimated that discharge values as a function of recession time were found to be consistently lower than the available discharge ones and the estimated groundwater volumes stored over time above the spring level turned out to be underestimated. Continuous (hourly value) and long-term Q, EC and T values are, therefore, needful to correctly quantify and to make a proper management of groundwater resources in mountain areas