Evaluation of the Laguerre-Gaussian mode purity produced by three-dimensional-printed microwave spiral phase plates.

Computer-aided design software and additive manufacturing provide flexibility for the direct fabrication of multi-material devices. This design and fabrication versatility has been investigated for the manufacture of dielectric spiral phase plates (SPP) that generate electromagnetic waves with helical wavefronts. Three types of SPPs designed to produce an orbital angular momentum (OAM) mode number l = |1| were additively manufactured using material extrusion and polyjet fabrication methods. The OAM mode characteristics of the transformed helical microwaves as a function of the SPP geometrical features were investigated experimentally in the 12-18 GHz frequency range. The SPPs were further combined with an additively manufactured dielectric lens that provided a marked improvement in OAM mode purity. Finally, multiplexing and de-multiplexing of two OAM modes were demonstrated successfully using an optimum SPP geometry and arrangement.

Experimental evaluation of 3D printed spiral phase plates for enabling an orbital angular momentum multiplexed radio system.

This paper evaluates the performance of three-dimensionally (3D) printed spiral phase plates (SPPs) for enabling an orbital angular momentum (OAM) multiplexed radio system. The design and realization of the SPPs by means of additive manufacturing exploiting a high-permittivity material is described. Modes 1 and 2 SPPs are then evaluated at 15 GHz in terms of 3D complex radiation pattern, mode purity and beam collimation by means of a 3D printed dielectric lens. The results with the lens yield a crosstalk of -8 dB for between modes 1 and -1, and -11.4 dB for between modes 2 and -2. We suggest a mode multiplexer architecture that is expected to further reduce the crosstalk for each mode. An additional loss of 4.2 dB is incurred with the SPPs inserted into the communication link, which is undesirable for obtaining reliable LTE-based communications. Thus, we suggest: using lower loss materials, seeking ways to reduce material interface reflections or alternative ways of OAM multiplexing to realize a viable OAM multiplexed radio system.

Microwave dielectric characterisation of 3D-printed BaTiO3/ABS polymer composites.

3D printing is used extensively in product prototyping and continues to emerge as a viable option for the direct manufacture of final parts. It is known that dielectric materials with relatively high real permittivity-which are required in important technology sectors such as electronics and communications-may be 3D printed using a variety of techniques. Among these, the fused deposition of polymer composites is particularly straightforward but the range of dielectric permittivities available through commercial feedstock materials is limited. Here we report on the fabrication of a series of composites composed of various loadings of BaTiO3 microparticles in the polymer acrylonitrile butadiene styrene (ABS), which may be used with a commercial desktop 3D printer to produce printed parts containing user-defined regions with high permittivity. The microwave dielectric properties of printed parts with BaTiO3 loadings up to 70 wt% were characterised using a 15 GHz split post dielectric resonator and had real relative permittivities in the range 2.6-8.7 and loss tangents in the range 0.005-0.027. Permittivities were reproducible over the entire process, and matched those of bulk unprinted materials, to within ~1%, suggesting that the technique may be employed as a viable manufacturing process for dielectric composites.

Mapping of multi-elements during melting and solidification using synchrotron X-rays and pixel-based spectroscopy.

A new synchrotron-based technique for elemental imaging that combines radiography and fluorescence spectroscopy has been developed and applied to study the spatial distribution of Ag, Zr and Mo in an Al alloy during heating and melting to 700, and then re-soldification. For the first time, multi-element distributions have been mapped independently and simultaneously, showing the dissolution of Ag- and Zr-rich particles during melting and the inter-dendritic segregation of Ag during re-solidification. The new technique is shown to have wide potential for metallurgical and materials science applications where the dynamics of elemental re-distribution and segregation in complex alloys is of importance.

Manufacture of electrical and magnetic graded and anisotropic materials for novel manipulations of microwaves.

Spatial transformations (ST) provide a design framework to generate a required spatial distribution of electrical and magnetic properties of materials to effect manipulations of electromagnetic waves. To obtain the electromagnetic properties required by these designs, the most common materials approach has involved periodic arrays of metal-containing subwavelength elements. While aspects of ST theory have been confirmed using these structures, they are often disadvantaged by narrowband operation, high losses and difficulties in implementation. An all-dielectric approach involves weaker interactions with applied fields, but may offer more flexibility for practical implementation. This paper investigates manufacturing approaches to produce composite materials that may be conveniently arranged spatially, according to ST-based designs. A key aim is to highlight the limitations and possibilities of various manufacturing approaches, to constrain designs to those that may be achievable. The article focuses on polymer-based nano- and microcomposites in which interactions with microwaves are achieved by loading the polymers with high-permittivity and high-permeability particles, and manufacturing approaches based on spray deposition, extrusion, casting and additive manufacture.

The role of the infection control professional in the intensive care unit.

By design, multiple invasive procedures are performed in the intensive care unit (ICU). Although great care is taken to control morbidity and forestall mortality, this invasive environment places ICU patients and staff at immense risk of nosocomial (hospital-acquired) infection. The role of the infection control professional (ICP) within the ICU involves data collection, dissemination of data with feedback, expertise in the investigation of outbreaks, product evaluation proficiency, and fluid consultation aptitude. This article provides an inside view of how specialty infection control staff and ICU staff can optimize infection control to decrease the incidence of nosocomial infections. A description of what the ICP does not do in the ICU is also given, providing a clear guideline for how these two disciplines can best provide a safe intensive care experience.

Evaluation of infection control parameters according to the 1994 Centers for Disease Control and Prevention Tuberculosis guidelines: a 2-year experience.

BACKGROUND: Because of classification as a high-risk institution for potential Mycobacterium tuberculosis exposure and an employee purified protein derivative conversion rate of 2.7%, a large university-affiliated county hospital enhanced administrative and engineering controls, as recommended by its tuberculosis task force in early 1994. METHODS: For 1994 and 1995 the medical records of all patients with culture-confirmed M. tuberculosis were reviewed according to the 1994 Centers for Disease Control and Prevention guidelines for case surveillance and risk assessment (infection control parameters). The chi 2-test was used to compare 1994 and 1995 infection control parameters for statistical significance (p < or = 0.05). RESULTS: In 1994 and 1995 there were 253 patients with tuberculosis, 85% of whom (214/253) had pulmonary-site tuberculosis. The "representative" patient with pulmonary tuberculosis was profiled, along with institution-specific surveillance data on diagnostics, medication regimens, and airborne isolation practices. Between 1994 and 1995 there was a trend toward increased numbers of homeless patients with tuberculosis, from 8.2% to 17% (p = 0.07). Decreases in the numbers of HIV seropositive patients with tuberculosis from 35% in 1994 to 24% in 1995 (p = 0.2) and of jailed patients with tuberculosis from 9.8% to 5% (p = 0.5) were not significant. Drug-resistance patterns increased from 13% to 24%, with borderline significance (p = 0.06). The employee purified protein derivative testing compliance rate increased from 49% in 1994 to 74% in 1995, with the purified protein derivative conversion rate also increasing from 2.7% to 3.5%. CONCLUSION: The infection control parameter data were beneficial in identification of institution-specific risk factors for our population with tuberculosis. Although labor-intensive, the annual tuberculosis reports supported requests for administrative and engineering controls; however, efficacy of the 1994 tuberculosis control plan was difficult to assess from purified protein derivative conversion rates alone, because the testing compliance rate also increased.

Manage nurse stress and increase potential at the bedside.

The nursing profession must continue to cement recognition as a powerful and innovative force in health care by first "caring for themselves" at the bedside for the goal of patient continuity of care. The negative effects of stress, both internal and external, major, minor, and adaptive, are rooted in the nurses occupational stress level, and how that level influences the continuity of care. Stress assessments and unit specific stress management sessions need to become ingrained within the health care environment by instituting "comprehensive" stress management programs. Communicative "healing" needs to flow from the bedside to the CEO and back down again.

Cost appropriateness: can we $afford$ another Medical Waste Tracking Act?

Medical waste has, with each passing year, become a subject of greater and greater concern for the general public, legislative bodies, and the healthcare industry. Regulations have been passed and governing organizations created to set the problem right. These actions have cost the healthcare industry (and thus the public) exorbitant amounts of money. But is the panic wrongly focused, and is money being spent on the wrong things? This article discusses these issues and makes some eye-opening revelations about the medical waste crisis.

Perceived control: bogus pulse rate feedback and reported symptom reduction for individuals with accumulated stressful life events.

The present investigation tested the hypothesis that perceived control reduces reported symptom incidence for individuals with stressful life events. Subjects (undergraduate psychology students from an urban university) were divided into two groups, high and low in stress, based on their life change unit scores as measured by the Schedule of Recent Events (Holmes & Rahe, 1967). Subjects participated in a study in which they attempted to reduce pulse rate (PR) and were informed of their successes (i.e., PR reductions) through bogus feedback. High and low stress subjects were assigned randomly to one of the following conditions: bogus ascending success feedback (AS), wherein successes were concentrated more in the later stage of a PR reduction period; bogus equally distributed success feedback (EDS), wherein successes were equally distributed in the early and later stages of a PR reduction period; or no feedback (NF). The study consisted of three sessions held on 3 consecutive days. Each session consisted of a 3-minute baseline (nonfeedback) period followed by a 10-minute PR reduction period. Self-reports on 13 symptom items were measured 2 weeks before the study (pretest), after the final session of the study (posttest), and 3 weeks after the study (follow-up). Results indicated that on 5 of the 13 symptom items, the AS condition produced a significant reduction in reported symptom incidence for high-stress subjects only, and this effect was maintained for 3 weeks after the experiment. Results are discussed in terms of the effect perceived control may have on perceptions of physical health. Suggestions are made regarding the use of biofeedback treatment as a method by which perceptions of symptom distress may be reduced for individuals exposed to cumulative stressful experiences.

The hormonal control and morphology of blastocyst invasion in the mouse uterus.

When mature and immature uteri from ovariectomized mice were cultured in chemically defined media, blastocyst invasion occurred in the presence of progesterone but not in media containing only oestradiol. The invaded stromal tissue did not decidualize unless the uteri were taken from mice pretreated with progesterone and oestradiol. Fibrillar material was, however, concentrated in the stromal tissue adjacent to the invasive trophoblast. Neither progesterone nor oestradiol, had any ultrastructural effect on the endometrium of cultured uteri from ovariectomized mice, other than closure of uterine lumina in the presence of progesterone. Embryogenesis became abnormal, probably owing to the failure of formation of a suitable implantation chamber.