9,565 research outputs found
Tunable, Functional Diblock Copolypeptide Hydrogels Based on Methionine Homologs.
The preparation of new diblock copolypeptide hydrogels derived from homologs of l-methionine, that is, l-homomethionine and l-6-(methylthio)-l-norleucine is described. Compared to l-methionine residues, use of l-methionine homologs allow improved copolymerization with l-leucine residues to give well-defined block copolypeptides. These copolypeptides are subsequently modified using robust thioether alkylation reactions employing a variety of functional epoxides, which yield samples capable of forming transparent, self-healing hydrogels in water. The facile variation of different functional epoxides for postpolymerization modification is found to allow predictable functionalization and tuning of hydrogel properties by the modification of simple precursors
AFM Dissipation Topography of Soliton Superstructures in Adsorbed Overlayers
In the atomic force microscope, the nanoscale force topography of even
complex surface superstructures is extracted by the changing vibration
frequency of a scanning tip. An alternative dissipation topography with similar
or even better contrast has been demonstrated recently by mapping the
(x,y)-dependent tip damping but the detailed damping mechanism is still
unknown. Here we identify two different tip dissipation mechanisms: local
mechanical softness and hysteresis. Motivated by recent data, we describe both
of them in a onedimensional model of Moire' superstructures of incommensurate
overlayers. Local softness at "soliton" defects yields a dissipation contrast
that can be much larger than the corresponding density or corrugation contrast.
At realistically low vibration frequencies, however, a much stronger and more
effective dissipation is caused by the tip-induced nonlinear jumping of the
soliton, naturally developing bistability and hysteresis. Signatures of this
mechanism are proposed for experimental identification.Comment: 5 pages, 5 figures, Phys Rev B 81, 045417 (2010
Cut-free Calculi and Relational Semantics for Temporal STIT Logics
We present cut-free labelled sequent calculi for a central formalism in logics of agency: STIT logics with temporal operators. These include sequent systems for Ldm , Tstit and Xstit. All calculi presented possess essential structural properties such as contraction- and cut-admissibility. The labelled calculi G3Ldm and G3Tstit are shown sound and complete relative to irreflexive temporal frames. Additionally, we extend current results by showing that also Xstit can be characterized through relational frames, omitting the use of BT+AC frames
Radical Generic Initial Ideals
In this paper, we survey the theory of Cartwright\u2013Sturmfels ideals. These are \u2124n-graded ideals, whose multigraded generic initial ideal is radical. Cartwright\u2013Sturmfels ideals have surprising properties, mostly stemming from the fact that their Hilbert scheme only contains one Borel-fixed point. This has consequences, e.g., on their universal Gr\uf6bner bases and on the family of their initial ideals. In this paper, we discuss several known classes of Cartwright\u2013Sturmfels ideals and we find a new one. Among determinantal ideals of same-size minors of a matrix of variables and Schubert determinantal ideals, we are able to characterize those that are Cartwright\u2013Sturmfels
What factors affect the selection of industrial wastewater treatment configuration?
Industrial wastewater treatment is gaining significance in literature due to stricter environmental policies and increased environmental awareness. The selection of the wastewater configuration encompasses both the treatment as well as several decisions around wastewater collection and disposal pertaining industrial decision-making sphere. However, so far in the wastewater literature, research has mostly discussed either technical features of wastewater technologies, or wastewater policy issues at broader level, without focusing on the industrial decision-making issues and driving factors leading to the selection of a specific configuration. Starting from a literature review, the present study provides an innovative framework of the possible options for wastewater system configuration, as well as major adoption factors by industrial decision-makers. The factors have been classified according to 7 categories, namely: influent-related, technological, economic/financial, internal socio-cultural, external socio-cultural, regulation, site characteristics. The framework, validated with acknowledgeable experts, policy makers and firms, has been preliminarily applied to Italian and Australian food firms. Our investigation reveals that the framework was able to include all relevant problems faced by industries in the selection of a treatment system configuration; besides, the relative importance of factors has been assessed: legal requirements emerge as the most critical factors, followed by volume and discharge fee, the latter particularly interesting for policy makers purposes, since it may guide the decision-making process. Further, the wastewater volume seems to play a key role in our exploratory investigation, with smaller firms preferring a complete off-site treatment to reduce the complexity, whilst larger firms preferring instead more partial or complete on-site treatment configurations for compliance costs reduction. In conclusion, we have provided policy and managerial implications stemming from the study as well as sketched interesting future research avenues
Fine-Structure Map of the Histidine Transport Genes in \u3cem\u3eSalmonella typhimurium\u3c/em\u3e
Afine-structure genetic map of the histidine transport region of the Salmonella typhimurium chromosome was constructed. Twenty-five deletion mutants were isolated and used for dividing the hisJ and hisP genes into 8 and 13 regions respectively. A total of 308 mutations, spontaneous and mutagen induced, have been placed in these regions by deletion mapping. The histidine transport operon is presumed to be constituted of genes dhuA, hisJ, and hisP, and the regulation of the hosP and hisJ genes by dhuA is discussed. The orientation of this operon relative to purF has been established by three-point crosses as being: purF duhA hisJ hisP
Oral contraceptives and primary liver cancer.
The relative risk for developing primary liver cancer in northern Italian users of oral contraceptives, compared to matched controls was calculated based on reported cases in hospitals in the greater Milan area from 1984-1987. The incidence of and mortality from primary liver cancer, as well as the prevalence of oral contraceptive usage, have both been rising to Italy since the late 1950s. 21 cases of liver cancer, in women aged 32-59 (median 50), occurred in the Milan area during the study period. These women, and 145 controls matched for age but admitted to hospitals for a variety of non-neoplastic diseases, were interviewed with a structured questionnaire covering socio-demographics, life style, diet, medical history, and history of use of oral contraceptives and other drugs. 19.0% of the cases had used oral contraceptives compared to 7.6% of controls, a relative risk of 1.8 for up to 5 years' use, and 8.3 for 5 years. History of hepatitis was associated with 14% of cases and 7% of controls. Italians have a higher incidence of liver neoplasms that northern Europeans and Americans, probably because of higher incidence of risk factors, such as hepatitis and alcohol use. The attributable risk for oral contraception, however, is lower in this population
A Voltage Unbalance Mitigation Technique for Low-voltage Applications with Large Single-phase Loads
In this paper a voltage unbalance mitigation technique for low-voltage microgrids or feeders in presence of large single-phase loads is introduced. In order to take maximum advantage of the existing hardware, the proposed solution consists of a sequence-based decentralized voltage control to be embedded in three-phase VSC connecting distributed generation to the considered system. Furthermore, a centralized controller is proposed to define optimal negative and zero sequence voltage reference. Control effectiveness is numerically verified considering a low-voltage feeder case study
Prevalence of COVID 19 like symptoms in Italy and Lombardy, March-April 2020, and their implications on cancer prevention, diagnosis and management
Two population-based surveys on coronavirus disease-2019 (Covid-19)-like symptoms were conducted by BVA-Doxa on representative samples of the general population from Italy and its largest region, Lombardy, with over 10 million inhabitants and heavily struck by Covid-19, on 27-30 March and 3-7 April, on a total of 2000 individuals - 353 from Lombardy. Overall, 14.2% of Italians - and 19.6% in Lombardy - reported Covid-19-like symptoms. The estimated prevalence was higher in the young, in smokers, and in Lombardy over the period 20 March to 7 April. Although the influenza season was ended by mid-March, at least part of the symptoms may be not Covid-19 related. Even assuming that only half are, at least 7% of Italians and 10% in Lombardy had been affected by Covid-19. To these, asymptomatic or paucisymptomatic cases have to be added. These estimates are at least one or two orders of magnitude larger than official registered cases. This has major implications for cancer prevention, management and treatment
Biometric characterization of the Red-legged Partridges Alectoris rufa of northwestern Italy
The biometrics of the Red-legged Partridge Alectoris rufa has been relatively well studied in the western part of its distribution range (Iberian Peninsula and France), especially due to the available large hunting bag samples. Conversely, the Italian population is poorly characterized. We analysed a sample of 254 live birds trapped and ringed in the northern Apennines (province of Alessandria, northwestern Italy), by measuring body mass and the length of wing, eighth primary, tail, tarsus and bill. We found significant differences in some biometric measurements between sex and age classes. A subsample of birds (n = 112) was genetically tested for introgressive hybridization with A. chukar, an introduced species, showing that 16.1 % of free-living partridge are hybrid individuals. When we analysed separately "pure"and "introgressed"birds we found only small biometric differences in body mass of adult males. Finally, our results were compared with the biometry of other populations from the whole natural range of the species (France, Spain and Portugal) showing a negative biometric trend of wing length from westernmost to southeastern birds of the range. Introgressed birds found in the studied population were not easily distinguishable with biometric criteria from pure A. rufa rufa, so genetic analysis is highly recommended when planning reintroductions or restocking
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