Stereolithography Cure Process Modeling Using Acrylate Resin

In this paper, a complex stereolithography (SL) cure process model is presented that incorporates transient thermal and chemical effects which influence final part shape and properties. The model incorporates photopolymerization, mass diffusion, and heat transfer. Material properties are characterized and a comprehensive kinetic model parameterized for a model compound system. SL process simulations are performed using finite element methods with the software package FEMLAB, and validated by the capability of predicting the fabricated part dimensions. A degree of cure (DOC) threshold model is proposed which can predict the cure line size within 15% error, comparing with 30% prediction error by the exposure threshold model currently used in SL. Furthermore, through the sensitivity analysis conducted by the process model presented here, the sensitive parameters are identified and the SL bath temperature, photointiator absorptivity and concentration are found to be the most sensitive factors that affect the SL fabrication results. The sensitive variables will be the focus of further research meant to improve SL process speed and resolution.Mechanical Engineerin

Sphaerodactylus vincenti

Number of Pages: 6Integrative BiologyGeological Science

Modification of Coulomb's law in closed spaces

We obtain a modified version of Coulomb's law in two- and three-dimensional closed spaces. We demonstrate that in a closed space the total electric charge must be zero. We also discuss the relation between total charge neutrality of a isotropic and homogenous universe to whether or not its spatial sector is closed.Comment: 11 pages, 3 figure

Why We Fight: A Study of U.S. Government War-Making Propaganda

The article of record as published may be found at http://www.jstor.com/stable/26591800In this paper, we examine the extent to which officials within the U.S. government employ propaganda to influence the American public's opinion regarding going to war. We begin with a definition of propaganda as "the deliberate attempt to persuade people to think and behave in a desired way" (Taylor 1995, 6, emphasis in original), to which we add, "using means that involve either selective information or outright deception." We concentrate primarily on the public statements or actions of the president, secretary of defense, and high-ranking members of the military, though we also allow for the products of various other agencies insofar as they relate to foreign policy

Time To End Draft Registration

The article of record as published may be found at https://www.hoover.org/research/time-end-draft-registrationIn December, Secretary of Defense Ashton Carter announced that the military would no longer exclude women from any occupational specialty on the basis of gender. This new policy has broad implications for the Selective Service System. Although the last draftee entered the military in 1973, nearly all young men in the United States must register with the Selective Service System to be ready in case the draft is ever reinstated

Measuring atomic NOON-states and using them to make precision measurements

A scheme for creating NOON-states of the quasi-momentum of ultra-cold atoms has recently been proposed [New J. Phys. 8, 180 (2006)]. This was achieved by trapping the atoms in an optical lattice in a ring configuration and rotating the potential at a rate equal to half a quantum of angular momentum . In this paper we present a scheme for confirming that a NOON-state has indeed been created. This is achieved by spectroscopically mapping out the anti-crossing between the ground and first excited levels by modulating the rate at which the potential is rotated. Finally we show how the NOON-state can be used to make precision measurements of rotation.Comment: 14 preprint pages, 7 figure

Colloidal Electrostatic Interactions Near a Conducting Surface

Charge-stabilized colloidal spheres dispersed in deionized water are supposed to repel each other. Instead, artifact-corrected video microscopy measurements reveal an anomalous long-ranged like-charge attraction in the interparticle pair potential when the spheres are confined to a layer by even a single charged glass surface. These attractions can be masked by electrostatic repulsions at low ionic strengths. Coating the bounding surfaces with a conducting gold layer suppresses the attraction. These observations suggest a possible mechanism for confinement-induced attractions.Comment: 4 pages, 2 figure

Health inequalities, multimorbidity, and primary care in Scotland

Scotland has an ageing population and the widest health inequalities in Western Europe. Multiple health conditions develop ∼10–15 years earlier in deprived areas than in affluent areas. General practice is central to the effective and safe management of such complex multiple health conditions, but the inverse care law has permeated deprived communities (‘Deep End’ general practices) for the past 50 years. A new, radical, Scottish GP contract was introduced in April 2018, which has a vision to improve quality of care through cluster working and expansion of the multidisciplinary team (MDT), enabling GPs to deliver ‘expert generalism’ to patients with complex needs. It states a specific intention to address health inequalities and also to support the integration of health and social care. Here, we discuss recent evidence for whether the ambition of the new GP contract, to reduce health inequalities, is being achieved