A System of Interaction and Structure

This paper introduces a logical system, called BV, which extends multiplicative linear logic by a non-commutative self-dual logical operator. This extension is particularly challenging for the sequent calculus, and so far it is not achieved therein. It becomes very natural in a new formalism, called the calculus of structures, which is the main contribution of this work. Structures are formulae submitted to certain equational laws typical of sequents. The calculus of structures is obtained by generalising the sequent calculus in such a way that a new top-down symmetry of derivations is observed, and it employs inference rules that rewrite inside structures at any depth. These properties, in addition to allow the design of BV, yield a modular proof of cut elimination.Comment: This is the authoritative version of the article, with readable pictures, in colour, also available at . (The published version contains errors introduced by the editorial processing.) Web site for Deep Inference and the Calculus of Structures at <http://alessio.guglielmi.name/res/cos

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Thesis (Ed.M.)--Boston Universit

Records Of The Late Glacial Influx Of Ice-Rafted Detritus On The Orphan Knoll, Northwest Atlantic Ocean

The top 110 centimeters of IRD records for GVY002 reveal 5 distinct peaks in IRD input, each between 4000-6500 lithics/gram. Three of these peaks coincide with three peaks in the Ca/Sr ratios in the upper meter indicative of dolomite rich IRD from the Canadian margin. The IRD record and Ca/Sr ratio record generated in this study, when compared to the previously generated similar records in GVY001, reveals a similar pattern but over a much longer downcore sediment interval (over the upper 4.5 meters in GVY001 versus the upper 1.8 meters in GVY002). This is due to the higher sedimentation rate in GVY001. Hendry, et al. (2019) tentatively correlated the shallowest peaks in Ca/Sr ratios with Heinrich Events H0 - H4 by correlating the Ca/Sr ratio records in GVY001 to the δ18O record of N. pachyderma (s.). An IRD peak in GVY001 corresponds to each of the Heinrich Events identified in Hendry, et al. (2019). Subsequent comparison of GVY002 IRD records with those of GVY001 suggest that Heinrich Events H0, H1, and H2 can be identified over the first meter. Both GVY002 and GVY001 display two additional IRD peaks of at least 4000 lithics/gram between H1 and H2 during intervals of very low Ca/Sr ratios

I servizi Internet: varietà o caos?

Dopo solo pochi anni dall'apparire di Internet sulla scena mondiale, e soprattutto nazionale, si è visto incrementare notevolmente sia il numero di servizi disponibili che la loro qualità. Ultimamente si è notato l'appiattimento dell'offerta su di un solo servizio che li possa inglobare tutti, il WWW, fornendo una interfaccia unica ai più variegati strumenti ed alle più sfrenate manifestazioni della genialità, creativa ed imprenditoriale, della mente umana. Tutto ciò porterà ad un 'caos' primordiale, od al 'villaggio globale' dove tutti potranno usufruire delle gioie della tecnologia senza esserne fagocitati

Temporal control of Wnt signaling is required for habenular neuron diversity and brain asymmetry

Precise temporal coordination of signaling processes is pivotal for cellular differentiation during embryonic development. A vast number of secreted molecules are produced and released by cells and tissues, and travel in the extracellular space. Whether they induce a signaling pathway and instruct cell fate, however, depends on a complex network of regulatory mechanisms, which are often not well understood. The conserved bilateral left-right asymmetrically formed habenulae of the zebrafish are an excellent model for investigating how signaling control facilitates the generation of defined neuronal populations. Wnt signaling is required for habenular neuron type specification, asymmetry and axonal connectivity. The temporal regulation of this pathway and the players involved have, however, remained unclear. We find that tightly regulated temporal restriction of Wnt signaling activity in habenular precursor cells is crucial for the diversity and asymmetry of habenular neuron populations. We suggest a feedback mechanism whereby the tumor suppressor Wnt inhibitory factor Wif1 controls the Wnt dynamics in the environment of habenular precursor cells. This mechanism might be common to other cell types, including tumor cells

Undiagnosed vertebral fractures influence quality of life in postmenopausal women with reduced ultrasound parameters.

Osteoporosis, a multifactorial systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue leading to increased bone fragility, is a worldwide public health problem. Vertebral fractures affect approximately 20% of postmenopausal women and are a hallmark of osteoporosis, but they may pass unnoticed, although they may lead to long-term immobility and disability. The aims of the present study were (1) to determine the prevalence and the severity of vertebral fractures in a large cohort of Italian women aged 60 years or older with reduced values of quantitative ultrasound parameters; and (2) to assess whether vertebral fractures and other variables may be associated with health-related quality of life. A total of 2450 women without back pain aged 60 years or older, after the completion of the Quality of Life Questionnaire of the European Foundation for Osteoporosis QUALEFFO, underwent quantitative ultrasound evaluation of the calcaneus; in those with a stiffness t-score of a parts per thousand currency sign -2 (n = 1194), radiographic evaluation of the thoracic and lumbar spine was carried out and then quantitative morphometry was performed by dedicated software (MorphoXpress). The radiographic analysis was carried out on 885 women who presented films of adequate quality. Multivariate regression was used to adjust for confounding variables. Of those who underwent radiographic analysis, 681 had no vertebral fractures, and 204 women (23.1%) had one or more previously undiagnosed vertebral fractures. The prevalence of previously undiagnosed vertebral fractures increased with advancing age with more than 30% of women older than 75 years having at least one fracture. Older age, body mass index, and severe vertebral fractures were independently associated with a worse total QUALEFFO score. We found that approximately one in four women showed evidence of undiagnosed vertebral fractures, and there was a strong age effect trend. Moreover, the severity grade of vertebral fractures, more than the number of fractures, was associated with a worsening of health-related quality of life as assessed by QUALEFFO. These findings confirm the clinical relevance of an early diagnosis of vertebral fractures and seem to support the usefulness of quantitative ultrasound measurements in the stratification of postmenopausal women at increased fracture risk

Efficiency of an Air Cleaner Device in Reducing Aerosol Particulate Matter (PM) in Indoor Environments

Abstract: Indoor air quality (IAQ) in household environments is mandatory since people spend most of their time in indoor environments. In order to guarantee a healthy environment, air purification devices are often employed. In the present work, a commercial household vacuum cleaner has been tested in order to verify its eciency in reducing the mass concentration and particle number of aerosol particulate matter (PM). The eciency has been tested measuring, while the instrument was working, PM10 (particles with aerodynamic diameter less than 10 m), PM2.5 (particles with aerodynamic diameter less than 2.5 m), PM1 (particles with aerodynamic diameter less than 1 m), and 7 size-fractions in the range between 0.3 and &gt;10 m. Measurements have been carried out by means of a portable optical particle counter instrument and simulating the working conditions typical of a household environment. It has been found that the tested commercial device significantly reduces both PM concentrations and particle number, especially in the finest fraction, i.e., particles in the range 0.3\u20130.5 m, allowing an improvement of indoor air quality