Shear Thickening and Scaling of the Elastic Modulus in a Fractal Colloidal System with Attractive Interactions

Dilute oil dispersions of fractal carbon black particles with attractive Van der Waals interactions display continuous shear thickening followed by shear thinning at high shear rates. The shear thickening transition occurs at $\dot\gamma_{c}\approx 10^{2}-10^{3}s^{-1}$ and is driven by hydrodynamic breakup of clusters. Pre-shearing dispersions at shear rates $\dot\gamma>\dot\gamma_{c}$ produces enhanced-modulus gels where $G' \sim \sigma_{pre-shear}^{1.5-2}$ and is directly proportional to the residual stress in the gel measured at a fixed sample age. The observed data can be accounted for using a simple scaling model for the breakup of fractal clusters under shear stress.Comment: 5 pages, 5 figures; v2: treating low shear rate date separately; edited title; reworked figure

Fabrication of comb-drive actuators for straining nanostructured suspended graphene

We report on the fabrication and characterization of an optimized comb-drive actuator design for strain-dependent transport measurements on suspended graphene. We fabricate devices from highly p-doped silicon using deep reactive ion etching with a chromium mask. Crucially, we implement a gold layer to reduce the device resistance from $\approx51.6$ k$\mathrm{\Omega}$ to $\approx236$ $\mathrm{\Omega}$ at room temperature in order to allow for strain-dependent transport measurements. The graphene is integrated by mechanically transferring it directly onto the actuator using a polymethylmethacrylate membrane. Importantly, the integrated graphene can be nanostructured afterwards to optimize device functionality. The minimum feature size of the structured suspended graphene is 30 nm, which allows for interesting device concepts such as mechanically-tunable nanoconstrictions. Finally, we characterize the fabricated devices by measuring the Raman spectrum as well as the a mechanical resonance frequency of an integrated graphene sheet for different strain values.Comment: 10 pages, 9 figure

An App for Third Party Beneficiaries

Every year, more than 100 reported court opinions consider the question of whether an outsider can sue for damages under a contract made by others—in part because the law is so ambiguous. While contract enforcement by a third party is controlled largely by the facts of the particular case, it also materially depends upon the relevant legal standards. At present, not just the standards, but also the reasons for these standards, are unclear. Eighty years ago, Lon Fuller, a professor teaching contracts at a then-Southern law school, and William Perdue, a student at that school, significantly clarified and improved decision-making on damages issues in contract law by proposing a new vocabulary and analytical model. The senior author of this Article is a professor at a Southern law school, but he does not need an academic Lloyd Bentsen to tell him that he is “no Lon Fuller,” and the younger co-authors hold no “William Perdue illusion,” given that Mr. Perdue was the father-in-law of their law school dean. Nonetheless, we believe that the new vocabulary and analytical model we are proposing would clarify and improve decision-making on third party contract rights

Steroid concentrations in atopic dermatitis patients: Reduced plasma DHEAS and increased cortisone levels.

Atopic dermatitis (AD) is a chronically relapsing inflammatory skin disease, which is characterized by a disrupted epidermal barrier function present both in affected skin and in non-affected skin. Mainly glucocorticosteroids were used in topical and systemic atopy treatments because of their potent anti-inflammatory effects, unfortunately with strong side effects. In this study we determined that 2 out of 16 steroids were significantly different in healthy volunteers vs AD-patients. Cortisone, which is higher in AD-patients plasma, is a direct precursor of the bioactive corticosteroid cortisol, which just displays a higher tendency and is known for its potent anti-inflammatory effects. In addition a tendency of reduced levels of the anti-inflammatory ER ligand estrone was found in AD-patients. DHEA is a precursor of testosterone, its levels just display a lower tendency in male AD-patients, while its sulfonation metabolite DHEAS is lower in male and female AD-patients. We found and conclude that altered steroid levels in the plasma of AD-patients indicate altered vitamin D signaling (based on reduced DHEA sulfonation) and increased feedback for anti-inflammatory signaling (increased levels of cortisone) present in AD-patients. This article is protected by copyright. All rights reserved

Integrated impedance bridge for absolute capacitance measurements at cryogenic temperatures and finite magnetic fields

We developed an impedance bridge that operates at cryogenic temperatures (down to 60 mK) and in perpendicular magnetic fields up to at least 12 T. This is achieved by mounting a GaAs HEMT amplifier perpendicular to a printed circuit board containing the device under test and thereby parallel to the magnetic field. The measured amplitude and phase of the output signal allows for the separation of the total impedance into an absolute capacitance and a resistance. Through a detailed noise characterization, we find that the best resolution is obtained when operating the HEMT amplifier at the highest gain. We obtained a resolution in the absolute capacitance of 6.4~aF$/\sqrt{\textrm{Hz}}$ at 77 K on a comb-drive actuator, while maintaining a small excitation amplitude of 15~$k_\text{B} T/e$. We show the magnetic field functionality of our impedance bridge by measuring the quantum Hall plateaus of a top-gated hBN/graphene/hBN heterostructure at 60~mK with a probe signal of 12.8~$k_\text{B} T/e$.Comment: 7 pages, 5 figure

Nonverbal behavior during standardized interviews in patients with schizophrenia spectrum disorders

Several studies have consistently shown that patients with schizophrenia or schizophrenia spectrum disorders (SSD) can be distinguished from normal controls on the basis of their nonverbal behavior during standardized interviews, with considerable interactions between negative symptoms and poor facial expressivity. However, most studies have examined unmedicated patients, and gender of both interviewer and interviewee has not been taken into account. In this study we assessed the nonverbal behavior of male and female patients with SSD who were receiving second-generation antipsychotic medication (SGA) using the Ethological Coding System for Interviews (Troisi, 1998). In addition, we used a novel 5-factor model of the Positive and Negative Symptom Scale (PANSS, van der Gaag et al., 2006) to correlate nonverbal behavior with standard psychopathology ratings. Our findings strongly resembled results of previous studies into nonverbal behavior of patients with SSD, despite differences in cultural backgrounds and gender of the interviewer. Negative symptoms were inversely correlated with several of the nonverbal behavioral dimensions. Medication dose did not correlate with any one of the behavioral or psychopathological measures. Patients with SSD make less use of their nonverbal behavioral repertoire compared with controls, independent of antipsychotic treatment. Culture-specific nonverbal expressivity seems to play an additional (minor) role in distinguishing patients from healthy controls

Facing the challenge of liquid phase crystallizing silicon on textured glass substrates

A major limitation in current liquid phase crystallized LPC silicon thin film record solar cells are optical losses caused by their planar glass silicon interface. In this study, silicon is grown on nanoimprinted periodically as well as on randomly textured glass substrates and successfully implemented into state of the art LPC silicon thin film solar cell stacks. By systematically varying every layer the whole sample stack is optimized regarding its anti reflection ability. Compared to an optimized planar reference device, a reduction of reflection losses by 3.5 absolute on the random and by 9.4 absolute on the periodic texture has been achieved in the wavelength range of interes