Density Matrix Renormalization Group and Quantum Information applied to Quantum Critical Phenomena in One-Dimensional Systems

We investigate three different types of quantum phase transition occurring in quasi one-dimensional systems theoretically and numerically. First, we study the band-insulator to Mott-insulator transition occurring in charge-transfer complexes, for which the half-filled one-dimensional ionic Hubbard model is considered to be the prototype model. The study is carried out by first deriving an effective spin-one model, and then studying the model numerically using the density matrix renormalization group. We perform a careful finite-size scaling analysis of the mass gaps, order-parameters, and relative susceptibility. We confirm the existence of two quantum critical points. Analysis of the critical exponents confirms that the band-insulator-to-spontaneously-dimerized phase transition belong to the 2D Ising class. The spontaneously dimerized phase undergoes a phase transition to the Mott-insulator which is an infinite-order. Second, we investigate the Mott metal-insulator transition for the half-filled Hubbard model with both nearest-neighbor t and next-nearest-neighbor t′ hopping terms. We study the model using the bosonization approach and density matrix renormalization group simulations. An effective low-energy Hamiltonian that describes the insulator-metal transition is derived. We present results of density matrix renormalization group calculations of spin and charge distribution in various sectors of the phase diagram. The numerical results support the picture derived from the effective theory and give evidence for the complete separation of the transitions involving the spin and the charge degrees of freedom. Finally, we investigate quantum phase transitions phases in low-dimensional fermionic and spin models that go from uniform to spatially inhomogeneous, i.e., dimerized, trimerized, or incommensurate, phases. We propose a new approach based on studying the length dependence of the von Neumann entropy and its corresponding Fourier spectrum for finite segments in the ground state of finite chains. Peaks at a nonzero wave vector are indicators of oscillatory behavior in decaying correlation functions and also provide significant information about certain relevant features of the excitation spectrum; in particular, they can identify the wave vector of soft modes in critical models

Prosociality predicts labor market success around the world

A large literature points to the importance of prosociality for the well-being of societies and individuals. However, most of this work is based on observations from western, educated, industrialized, rich, and democratic (WEIRD) societies, questioning the generalizability of these findings. Here we present a global investigation of the relation between prosociality and labor market success. Our analysis uses experimentally validated measures of prosociality and is based on about 80,000 individuals in 76 representative country samples. We show a sizable and robust positive relation between prosociality and labor market success around the world that does not systematically differ across continents or by countries’ economic development. These findings generalize the positive relation between prosociality and labor market success to a wide geographical context

Subjective Beliefs and Inclusion Policies: Evidence from College Admissions

Many countries have introduced preferential admissions to provide new opportunities for talented but disadvantaged students to attend college. Their effectiveness critically depends on students’ perceptions of their incentive schemes. This paper studies this issue by exploiting a randomized preferential admission policy and linked survey-administrative data for 6,054 high-school students in Chile. We document that these students hold overly optimistic beliefs about their admission credentials. We then estimate policy effects on student behavior and outcomes. We find that pre-college effort and achievement fall by 0.1 standard deviations in response to the policy. We develop and structurally estimate a dynamic model of effort, entrance-exam-taking, admissions and enrollments incorporating subjective beliefs. We show that, by distorting effort, belief biases lead overconfident but underprepared students to enter college in response to the policy. We discuss how preferential admission policies can be redesigned to mitigate such distortions and draw closer to achieving their intended objective

The Effect of Preferential Admissions on the College Participation of Disadvantaged Students: The Role of Pre-College Choices

Exploiting the randomized expansion of preferential college admissions in Chile, we show they increased admission and enrollment of disadvantaged students by 32%. But the intended beneficiaries were nearly three times as many, and of higher average ability, than those induced to be admitted. The evidence points to students making pre-college choices that caused this divergence. Using linked survey-administrative data, we present evidence consistent with students being averse to preferential enrollment, misperceiving their abilities, and having social preferences towards their friends (although social preferences did not mediate the admission impacts). Simulations from an estimated structural model suggest that aversion to the preferential channel more than halved the enrollment impacts, by inducing some to forgo preferential admission eligibility, and that students' misperceptions worsened the ability-composition of college entrants, by distorting pre-college investments into admission qualifications. The results demonstrate the importance of understanding high school students' preferences and beliefs when designing preferential admissions

Design Method for Contra-Rotating Propellers for High-Speed Crafts: Revising the Original Lerbs Theory in a Modern Perspective

The main theoretical and numerical aspects of a design method for optimum contrar-rotating (CR) propellers for fast marine crafts are presented. We propose a reformulated version of a well-known design theory for contra-rotating propellers, by taking advantage of a new fully numerical algorithm for the calculation of the mutually induced velocities and introducing new features such as numerical lifting surface corrections, use of an integrated modern cavitation/strength criteria, a modified method to consider different numbers of blades among the two propellers, and to allow for an unloading function in the search for the optimal circulation distribution. The paper first introduces the main theoretical principles of the new methods and then discusses the influence of the main design parameters on an emblematic example of application in the case of counter rotating propellers for a pod propulsor designed for fast planing crafts (35 knots and above)

Exosome-delivered microRNAs promote IFN-α secretion by human plasmacytoid DCs via TLR7

The excessive production of type I IFNs is a hallmark and a main pathogenic mechanism of many autoimmune diseases, including systemic lupus erythematosus (SLE). In these pathologies, the sustained secretion of type I IFNs is dependent on the improper activation of plasmacytoid DCs (pDCs) by self-nucleic acids. However, the nature and origin of pDC-activating self-nucleic acids is still incompletely characterized. Here, we report that exosomes isolated from the plasma of SLE patients can activate the secretion of IFN-α by human blood pDCs in vitro. This activation requires endosomal acidification and is recapitulated by microRNAs isolated from exosomes, suggesting that exosome-delivered microRNAs act as self-ligands of innate single-stranded endosomal RNA sensors. By using synthetic microRNAs, we identified an IFN induction motif that is responsible for the TLR7-dependent activation, maturation, and survival of human pDCs. These findings identify exosome-delivered microRNAs as potentially novel TLR7 endogenous ligands able to induce pDC activation in SLE patients. Therefore, microRNAs may represent novel pathogenic mediators in the onset of autoimmune reactions and potential therapeutic targets in the treatment of type I IFN-mediated diseases

Use Of A One-way Flutter Valve Drainage System In The Postoperative Period Following Lung Resection [utilização Da Válvula Unidirecional De Tórax Como Sistema De Drenagem No Pós-operatório De Ressecç ões Pulmonares]

Objective: To evaluate pleural drainage using a one-way flutter valve following elective lung resection. Methods: This was a prospective study, with descriptive analysis, of 39 lung resections performed using a one-way flutter valve to achieve pleural drainage during the postoperative period. Patients less than 12 years of age were excluded, as were those submitted to pneumonectomy or emergency surgery, those who were considered lost to follow-up and those in whom water-seal drainage was used as the initial method of pleural drainage. Lung expansion, duration of the drainage, hospital stay and postoperative complications were noted. Results: A total of 36 patients were included and analyzed in this study. The mean duration of pleural drainage was 3.0 ± 1.6 days. At 30 days after the surgical procedure, chest X-ray results were considered normal for 34 patients (95.2%). Postoperative complications occurred in 8 patients (22.4%) and were related to the drainage system in 3 (8.4%) of those. Conclusions: The use of a one-way flutter valve following elective lung resection was effective, was well tolerated and presented a low rate of complications.348559566Kenyon, J.H., Traumatic Hemothorax: Siphon drainage (1916) Ann Surg, 64, pp. 728-729Lilienthal, H., Resection of the lung for suppurative infections with a report based on 31 operative cases in which resection was done or intended (1922) Ann Surg, 75 (3), pp. 257-320Heimlich, H.J., Valve drainage of the pleural cavity (1968) Dis Chest, 53 (3), pp. 282-287Waller, D.A., Edwards, J.G., Rajesh, P.B., A physiological comparison of flutter valve drainage bags and underwater seal systems for postoperative air leaks (1999) Thorax, 54 (5), pp. 442-443Lima, A.G., Rocha, E.R., Santos, N.A., Seabra, J.C., Mussi, R.K., Santos, J.G., Avalia̧ão do uso da bra̧adeira ou "clamp" na drenagem pleural fechada subaquática. 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