Many-Body Density Matrices for Free Fermions

Building upon an analytical technique introduced by Chung and Peschel [M. Chung and I. Peschel, Phys. Rev. B 64, art. 064412 (2001)], we calculated the density matrix rho_B of a finite block of B sites within an infinite system of free spinless fermions. In terms of the block Green function matrix G (whose elements are G_ij = , where c_i^+ and c_j are fermion creation and annihilation operators acting on sites i and j within the block respectively), the density matrix can be written as rho_B = det(1 - G) exp[ sum_ij (log G(1 - G^{-1})_ij c_i^+ c_j]. Implications of such a result to Hilbert space truncation for real-space renormalization schemes is discussed.Comment: 12 pages in RevTeX4 format. Uses amsmath, bbold, dcolumn and mathrsfs package

Evaluation of the EMC environment generated by a static var compensator

Describes an evaluation of the EMC environment generated by a static var compensator

An analysis of the outer membrane of desulfovibrio vulgaris (Woolwich)

D.vulgaris (Woolwich) OMs can be extracted successfully and reproducibly from the cell envelopes by the selective solubilisation of cell membranes by sarkosyl. Three Omps (Omps 1, 2 & 3) occur consistently in the OMs of C-Fe, NC & C+Fe cells. NC C+Fe OMs have, in addition, minor proteins absent from C-Fe OMs. Omp2 band is seen to be enhanced in C-Fe and NC OMs as indicated by PAGE. PAGE-immunoblotting of LPS indicates heterogeneity of these molecules. Immunological analyses of NC, C-Fe & C+Fe cells using specific antisera indicate no differences among these cell-types. Neither are antigenic differences revealed by further analyses of OM Western blots by specific antisera. However, pyrolysis analyses indicate that the cell-types analyses show variations in the cell ability of this technique to bacterial species cultured under different growth conditions indicates its potential as a tool for numerical taxonomy of the sulphate reducers. D.vulgaris (Woolwich) does not produce extra Omps in response to iron deprivation. Instead, it increases the synthesis of 0mp2 and LPS in its OM as reflected in the OM PAGE pattern and increased yields of LPS extracted from C-Fe cultures. HPLC sugar analyses indicate the LPS contain N-glucosamine, possibly rhamnose and an unidentified sugar. A change in HPLC sugar pattern of the C+Fe LPS samples indicates interactions between Fe(II) and LPS. This interaction is substantiated by X-ray microanalysis of the elemental content extracted LPS. The evidence indicates that LPS may be involved in Fe(II) uptake by the cells. LPS also takes part in the adhesion of D.vulgaris (Woolwich) to mild steel surfaces. This is demonstrated by the data from experiments using anti-LPS Fab fragments. The presence of these antibodies reduces the number of cells adhering to mild steel coupons. Fe-radiolabelling of OM components immobilised on nitrocellulose shows that Omps 1, 2 & 3 bind Fe(II). Blocking experiments using copper & magnesium indicate Omp1 to be Fe(II) specific while Omps 2 3 are not. The enhancement of Omp2 observed in C-Fe NC OMs in PAGE analyses indicates Omp2 to be principal cation binder, whose synthesis is increased under iron deprivation

The Use of Engineering Sketching and Journaling to Foster Deep Understanding of Construction: an Exploratory Study

In today’s teaching environment where students’ main focus is on getting a high mark for a class, deep understanding has taken a backseat. Being able to answer as many exam preparation questions as possible and fulfilling all the criteria on an assignment will guarantee success. “I deserve a higher mark because I worked hard in this class,” are the arguments one hears after the final marks are published. How about understanding the new material presented in the class? Engineering sketching and journaling have been hailed by experienced engineers as tools to enhance thinking and communication. The authors of the paper report about their utilization as teaching tools to foster deep understanding in a course on construction equipment and methods. While topics like equipments economics, power transmission and safety benefit from graphing in two-axis coordinate systems, understanding the best path of a backhoe bucket during a trenching operation is impossible to describe in words. Of course, understanding has several components: a) WHY do we use a backhoe excavator and not a trencher, b) WHAT are the possible three link motion paths and their related force vectors, c) HOW can the operator control the path of the bucket, and d) WHAT-IF there are utilities buried in the ground

Exact ground states and correlation functions of chain and ladder models of interacting hardcore bosons or spinless fermions

By removing one empty site between two occupied sites, we map the ground states of chains of hardcore bosons and spinless fermions with infinite nearest-neighbor repulsion to ground states of chains of hardcore bosons and spinless fermions without nearest-neighbor repulsion respectively, and ultimately in terms of the one-dimensional Fermi sea. We then introduce the intervening-particle expansion, where we write correlation functions in such ground states as a systematic sum over conditional expectations, each of which can be ultimately mapped to a one-dimensional Fermi-sea expectation. Various ground-state correlation functions are calculated for the bosonic and fermionic chains with infinite nearest-neighbor repulsion, as well as for a ladder model of spinless fermions with infinite nearest-neighbor repulsion and correlated hopping in three limiting cases. We find that the decay of these correlation functions are governed by surprising power-law exponents.Comment: 20 pages, 18 figures, RevTeX4 clas

Correlation density matrix: an unbiased analysis of exact diagonalizations

Given the ground state wavefunction for an interacting lattice model, we define a "correlation density matrix"(CDM) for two disjoint, separated clusters $A$ and $B$, to be the density matrix of their union, minus the direct product of their respective density matrices. The CDM can be decomposed systematically by a numerical singular value decomposition, to provide a systematic and unbiased way to identify the operator(s) dominating the correlations, even unexpected ones.Comment: (4pp, 2 figures

Tourism Professionals Profile: Theme Park Managers

Theme park managers are a unique group of tourism managers. Their perspectives on effective tourism management skills and abilities differ from some public sector tourism managers. The authors present the results of a study focusing on theme park managers and compare these results with those of other tourism manager group

Medial septal cholinergic neurons modulate isoflurane anesthesia.

BACKGROUND: Cholinergic drugs are known to modulate the response of general anesthesia. However, the sensitivity of isoflurane or other volatile anesthetics after selective lesion of septal cholinergic neurons that project to the hippocampus is not known. METHODS: Male Long Evans rats had 192 immunoglobulin G-saporin infused into the medial septum (n = 10), in order to selectively lesion cholinergic neurons, whereas control, sham-lesioned rats were infused with saline (n = 12). Two weeks after septal infusion, the hypnotic properties of isoflurane and ketamine were measured using a behavioral endpoint of loss of righting reflex (LORR). Septal lesion was assessed by counting choline acetyltransferase-immunoreactive cells and parvalbumin-immunoreactive cells. RESULTS: Rats with 192 immunoglobulin G-saporin lesion, as compared with control rats with sham lesion, showed a 85% decrease in choline acetyltransferase-immunoreactive, but not parvalbumin-immunoreactive, neurons in the medial septal area. Lesioned as compared with control rats showed increased isoflurane sensitivity, characterized by a leftward shift of the graph plotting cumulative LORR percent with isoflurane dose. However, lesioned and control rats were not different in their LORR sensitivity to ketamine. When administered with 1.375% isoflurane, LORR induction time was shorter, whereas emergence time was longer, in lesioned as compared with control rats. Hippocampal 62-100 Hz gamma power in the electroencephalogram decreased with isoflurane dose, with a decrease that was greater in lesioned (n = 5) than control rats (n = 5). CONCLUSIONS: These findings suggest a role of the septal cholinergic neurons in modulating the sensitivity to isoflurane anesthesia, which affects both induction and emergence. The sensitivity of hippocampal gamma power to isoflurane appears to indicate anesthesia (LORR) sensitivity

Fumaric acid ester–induced renal Fanconi syndrome: evidence of mitochondrial toxicity

Background: Fumaric acid esters (FAEs) are used to treat chronic plaque psoriasis. Fumarate is a crucial component of the Krebs cycle and mitochondrial function. Proximal tubule cells have high energy demands and rely on aerobic respiration. Proximal tubular dysfunction can cause renal Fanconi syndrome and acute kidney injury. We sought to better understand the mechanism for this in the context of FAE therapy. Methods: We describe a case series of 10 patients with FAE-associated Fanconi syndrome. Patients were diagnosed and managed at a tertiary renal tubular disorder clinic, with examination of serum and urine biochemistry. Five patients had a renal biopsy with examination of the specimens by electron microscopy. Results: The median age was 36.5 years [interquartile range (IQR) 32.25–54.25]. The median dose of FAE was 720 mg/day (IQR 390–720). There was low molecular weight proteinuria: the median urinary retinol-binding protein (RBP) at presentation was 8385 μg/mL (IQR 2793–14 600) and the RBP:creatinine ratio was 710 (IQR 390–2415). All patients had hyperphosphaturia [median fractional excretion of phosphate 24.2% (IQR 20.8–26.9), normal range <20%] as well as relative hypophosphataemia, with a median serum phosphate concentration of 0.93 mmol/L (IQR 0.83–0.97). Renal histology showed proximal tubular damage and abnormal mitochondrial morphology. Two patients had a favourable biochemical response to treatment with probenecid. Conclusions: We document for the first time that FAE-associated renal Fanconi syndrome is associated with mitochondrial damage visible on electron microscopy. This effect may be ameliorated by antagonism of the organic anion transporter with probenecid

Hierarchical cache design for enhancing TCP over heterogeneous networks with wired and wireless links

In this paper, we propose a two-layer hierarchical cache architecture for enhancing TCP performance over heterogeneous networks with both wired and wireless links. A new network-layer protocol, called New Snoop, is designed. The main idea is to cache the unacknowledged packets at both Mobile Switch Center (MSC) and Base Station (BS), thus forming a two-layer cache hierarchy. If a packet is lost due to transmission errors in wireless link, the BS takes the responsibility to recover the loss. When a handoff occurs during a TCP connection session, the packets cached in MSC can help to minimize the latency of retransmissions due to temporal disconnection. Simulation results show that using New Snoop is significantly more robust in dealing with unreliable wireless links and handoffs as compared with the Snoop scheme as well as other existing TCP enhancements.published_or_final_versio