Phase-induced transport in atomic gases: from superfluid to Mott insulator

Recent experimental realizations of artificial gauge fields for cold atoms are promising for generating steady states carrying a mass current in strongly correlated systems, such as the Bose-Hubbard model. Moreover, a homogeneous condensate confined by hard-wall potentials from laser sheets has been demonstrated, which provides opportunities for probing the intrinsic transport properties of isolated quantum systems. Using the time-dependent Density Matrix Renormalization Group (TDMRG), we analyze the effect of the lattice and interaction strength on the current generated by a quench in the artificial vector potential when the density varies from low values (continuum limit) up to integer filling in the Mott-insulator regime. There is no observable mass current deep in the Mott-insulator state as one may expect. Other observable quantities used to characterize the quasi-steady state in the bulk of the system are the Drude weight and entanglement entropy production rate. The latter in particular provides a striking signature of the superfluid-Mott insulator transition. Furthermore, an interesting property of the superfluid state is the formation of shock and rarefaction waves at the boundaries due to the hard-wall confining potentials. We provide results for the height and the speed of the shock front that propagates from the boundary toward the center of the lattice. Our results should be verifiable with current experimental capabilities.Comment: 11 pages, 7 figures, final published versio

Synthesis, structural and dynamic investigation of chiral metal complexes

This thesis work epitomizes our experience in the solution structure investigation of chiral lanthanide complexes through a dual paramagnetic NMR/chiroptical spectroscopies method. During my work I have studied the LnM(hfbc)4 system (M alkali metal, hfbc = heptafluorobutyrilcamphorate) and pointed out the connection between the solution structure and its glum dissymetry factor. I have also pointed out a novel effect of enhancement of the VCD signal in presence of a paramagnetic Ln ion for chiral complexes or chiral adducts with natural occuring chiral organic molecules

Sexual Reward and Depression

Sexual behavior in male rats is a complex rewarding behavior and many neurotransmitters and neuropeptides play an important role in mediation of sexual performance, motivation and reward. The hypothalamic neuropeptide orexin has been shown play a key role in reward associated with food and drugs of abuse, but the role of this neuropeptide in control of sexual performance, motivation and reward is currently unclear. First, it was shown that orexin neurons in the hypothalamus are activated during sexual performance and reward. Next, using cell specific lesions of orexin neurons it was demonstrated that orexin is involved in arousal and anxiety, but is not critical for sexual performance or motivation. Moreover, orexin was shown to play a critical role in control of sexual reward. Thus, these studies provided novel information regarding a role for orexin in this natural reward behavior. Recent studies have shown that sexual behavior in male rats causes neuroplasticity in the mesolimbic system, enhanced psychostimulant-induced locomotor activity and drug craving. The latter of which is dependent on a period of abstinence from sexual behavior, suggesting an increased vulnerability for addiction following loss of sexual reward. Thus, the next goal of this thesis determined if abstinence from sexual behavior also leads increased vulnerability for other disorders related to reward processing, specifically depression-like behavior. It was demonstrated that a prolonged (28 day) but not short (1 or 7 day) period of abstinence causes depression-like behavior in sexually experienced male rats seen as increased passive stress coping behaviors and anhedonia. Development of depression-like behavior was associated with increased levels of corticotropin releasing factor mRNA in the paraventricular nucleus of the hypothalamus and increased hypothalamic-pituitary-adrenal axis activity in response to an acute stressor. Thus, these studies provide novel information on behavioral and neuroplastic alterations observed following a prolonged period of abstinence from mating and suggest that loss of sexual reward in male rats may be a paradigm to study depression following loss of social reward in humans

Optimal shape for a rectangular warehouse with a lateral receive / ship dock

Purpose: This technical note provides the mathematical demonstration for obtaining the optimal aspect ratio for a rectangular storage area with a lateral receive/ship dock, representing the standard configuration of modern distribution centers and logistic warehouses. The proposed aspect ratio is the one that minimizes the travel times of operators, keeping the common assumption of a storage area having a uniform access probability. Design/methodology/approach: To obtain the optimal aspect ratio of the storage area we model the entry point of the uniformly distributed dock with a random variable with a continuous uniform distribution, and we consequently evaluate the average travel path of the operator as a function of the latter. Successively, we estimate and minimize the average roundtrip length of the operator, leading to the optimal aspect ratio of the storage area. Findings: We find that the optimal aspect ratio between the warehouse width (U) and length (V) equals 1.5. The obtained result shows that the operators’ travel times are minimized with a storage area where . Research limitations/implications: Warehouses with a dock on one side now represent modern distribution centers' standard configuration. However, no optimal aspect ratio for the storage area has been discussed. For this reason, the paper fills this lack of scientific literature in the warehouse optimization research field by providing indications on how to design this class of warehouses. Practical implications: Distribution managers may find here guidance for defining a proper design of logistics centers and evaluating the operators' actual travel times to perform a roundtrip within the storage area. Originality/value: Traditional warehouse shape optimization models assume a single input/output point to the storage area. To our knowledge, no formal demonstration has been proposed for a warehouse with a dock on one entire sidePeer Reviewe

Distributional Solutions of Burgers’ type Equations for Intrinsic Graphs in Carnot Groups of Step 2

We prove that in arbitrary Carnot groups G of step 2, with a splitting G = W · L with L one-dimensional, the intrinsic graph of a continuous function φ : U ⊆ W → L is C1H -regular precisely when φ satisfies, in the distributional sense, a Burgers’ type system D φ φ = ω, with a continuous ω. We stress that this equivalence does not hold already in the easiest step-3 Carnot group, namely the Engel group. We notice that our results generalize previous works by Ambrosio-Serra Cassano-Vittone and Bigolin-Serra Cassano in the setting of Heisenberg groups. As a tool for the proof we show that a continuous distributional solution φ to a Burgers’ type system D φ φ = ω, with ω continuous, is actually a broad solution to D φ φ = ω. As a by-product of independent interest we obtain that all the continuous distributional solutions to D φ φ = ω, with ω continuous, enjoy 1/2-little H ̈older regularity along vertical directions