Correlated two-particle scattering on finite cavities

The correlated two-particle problem is solved analytically in the presence of a finite cavity. The method is demonstrated here in terms of exactly solvable models for both the cavity as well as the two-particle correlation where the two-particle potential is chosen in separable form. The two-particle phase shift is calculated and compared to the single-particle one. The two-particle bound state behavior is discussed and the influence of the cavity on the binding properties is calculated.Comment: Derivation shortened and corrected, 14 pages 10 figure

Using Motivational Interviewing in Public Health Practice to Prevent Fetal Alcohol Syndrome

Background: Surveys of women in prenatal care at busy clinics in Detroit, Michigan have reported 12.5% continue to drink during pregnancy (Flynn et al, 2003) and women in substance abuse treatment programs in Wayne County, MI have an incidence rate for Fetal Alcohol Syndrome (FAS) of 4 in 1,000 births, double the national prevalence rate of FAS. The goal of the current study was to intervene with women at high risk for an alcohol-exposed pregnancy using techniques of Brief Motivational Interviewing (BMI) in a verbal and written format. Methods: One third (33%) of 1,784 women screened at Detroit Department of Health and Wellness Promotion (DHWP) primary health care clinics and HIV/AIDS-STD clinic were found to be at risk of an alcohol exposed pregnancy defined as binge drinking (at least 4 drinks per occasion) or heavy drinking (8 or more drinks per week) in the last three months, while they were having sex with inconsistent or no contraception. This intervention utilized Brief Motivational Interviewing (BMI) and developed written materials based on the principles of BMI to 1) assess readiness for change, 2) strengthen motivation to change, and 3) provide an individualized change plan. For women who received the Individual Level Intervention (n = 77), four sessions of BMI were conducted (two in-person, two via telephone) over a six-month period. A Self-Guided Change version of the intervention (Community Level Intervention) was offered for women (n = 327) who preferred to utilize the materials at home and receive two follow-up telephone calls following baseline interview, also during a six-month period. Results: Both strategies, based on principles of Motivational Interviewing, have been shown to be effective in reducing drinking and increasing contraceptive use. Out of the 404 women participating in the program, 310 (77%) women completed at least one follow-up and were included in the analyses. Overall, 59.9% of the women enrolled in both interventions were no longer at risk for an alcohol-exposed pregnancy at the end of the intervention six months later. Conclusion: Brief Motivational Interviewing, delivered verbally or in a written format, is an effective method of reducing women’s risky behaviors for an alcohol exposed pregnancy. The Individual Level Intervention that included 2 face-to-face sessions resulted in less attrition than the Self-Guided Change version which relied on phone and mail contact only

Welding 3D Printed Structures for Composite Sacrificial Tooling

3D printed parts offer the ability to generate dimensioned, complex objects with minimal machining touch time and skill, but they are typically very weak and limited in size. Strong and light composite parts require tooling to be created for the fabric to lay on while the resin is curing, but tooling can be quite expensive during the prototyping phase or for low part quantity runs. This study examined the techniques required to weld smaller 3D printed parts together to form large 3D printed tools that could be used as a sacrificial tool for a composite part. In this method, the 3D printed structure would remain inside the part and provide support and dimensional reference during the composite curing process. Friction, hot extrusion, and hot contact welding methods were examined using lap shear joints in both tensile and flexural test methods to determine effective joinery style and overlap lengths to achieve normal 3D printed properties. The results of this study demonstrate how multiple 3D printers could be used to create cost-effective rapid prototyping and low part quantity runs for composite structures by welding smaller 3D printed structures into a larger single 3D printed part

A transfer matrix method for the analysis of fractal quantum potentials

The scattering properties of quantum particles on fractal potentials at different stages of fractal growth are obtained by means of the transfer matrix method. This approach can be easily adopted for project assignments in introductory quantum mechanics for undergraduates. The reflection coefficients for both the fractal potential and the finite periodic potential are calculated and compared. It is shown that the reflection coefficient for the fractal has a self-similar structure associated with the fractal distribution of the potential

All-fibre source of amplitude-squeezed light pulses

An all-fibre source of amplitude squeezed solitons utilizing the self-phase modulation in an asymmetric Sagnac interferometer is experimentally demonstrated. The asymmetry of the interferometer is passively controlled by an integrated fibre coupler, allowing for the optimisation of the noise reduction. We have carefully studied the dependence of the amplitude noise on the asymmetry and the power launched into the Sagnac interferometer. Qualitatively, we find good agreement between the experimental results, a semi-classical theory and earlier numerical calculations [Schmitt etl.al., PRL Vol. 81, p.2446, (1998)]. The stability and flexibility of this all-fibre source makes it particularly well suited to applications in quantum information science

Additive Manufacturing and Performance of Architectured Cement-Based Materials

There is an increasing interest in hierarchical design and Additive Manufacturing (AM)of cement-based materials. However, the brittle behavior of these materials and the presence of interfaces from the additive manufacturing process represent the current major challenges. Our work focuses on harnessing the heterogeneous interfaces by employing clever designs from bio-inspired Bouligand architectured materials. In this paper, we aim to demonstrate some key mechanisms that can allow brittle hardened cement-based materials to gain flaw-tolerant properties. Mechanisms such as cracktwisting at the interfaces have been previously observed in naturally-occurring orsynthetic composite Bouligand architectures. In this paper, a heterogeneous interface with porous characteristics in 3D-printed solid hardened cement paste (hcp)architectures were characterized. We hypothesize that the presence of heterogeneous interface in 3D-printed hardened cement paste (hcp) elements, in conjunction with clever architectures, promote key damage mechanisms such as interfacial cracking and crack twisting that lead to damage delocalization. This delocalization can be energetically favorable and allow energy dissipation and promote toughening and flaw-tolerant properties. We found that these architectures can enhance the properties from the typical strength-porosity relationship, classically known for brittle hcp materials

The hERG channel is dependent upon the Hsp90α isoform for maturation and trafficking

Heat shock protein 90 (Hsp90) has emerged as a promising therapeutic target for the treatment of cancer. Several Hsp90 inhibitors have entered clinical trials. However, some toxicological detriments have arisen, such as cardiotoxicity resulting from hERG inhibition following the administration of Hsp90 inhibitors. We sought to investigate this toxicity as hERG has been previously reported as a client protein that depends upon Hsp90 for its maturation and functional trafficking. In this study we show that hERG depends upon a single Hsp90 isoform. hERG preferentially co-immunoprecipitated with Hsp90α and genetic knockdown of Hsp90α, but not Hsp90β, resulted in a trafficking-defective hERG channel. This study demonstrates the importance of delineating the isoform dependence of Hsp90 client proteins and provides rationale for the design of isoform-selective Hsp90 inhibitors that avoid detrimental effect