Electromagnetic MEMS microspeaker for portable electronic devices

This work presents the conception, the microfabrication, and the electroacoustic characterization of a new electromagnetic microspeaker based on silicon. The objectives are to get improved sound quality compared to that of conventional microspeakers, while keeping the electroacoustic efficiency as high as possible. An optimized stiffening silicon microstructure let the sound radiator be extremely light and rigid. The mobile part is suspended to the fixed part by silicon suspension springs, which enable large out-of-plane displacement. The acoustic radiator is actuated by an electromagnetic motor, composed of a fixed permanent magnet and a planar coil located on top of the silicon radiator. The piston-like motion of the radiator favored by this structure is very beneficial for the sound quality. Electro–mechano–acoustic characterization of the microfabricated microspeaker showed that the radiator surface could run out-of-plane with displacements higher than ±400 μm, with no mechanical and electrical failure. For an electrical power of 0.5 W, the microspeaker was capable to generate a sound pressure level of 80 dB at 10 cm, from 330 Hz up to 20 kHz frequency. The efficiency reaches 3 × 10^?5, that is to say three times more than typical efficiency of conventional microspeakers. Moreover, as characterization results showed, the existence of very few structural modes and the low electroacoustic distortions evidence the high sound quality of the microspeaker.     

Design of LTCC with High Thermal Expansion

New applications of low-temperature co-fired ceramics (LTCC), such as pressure sensors or integrated functional layers, require materials that possess higher coefficients of thermal expansion (CTE). To fabricate LTCC with elevated CTE, two methods of material design are examined: firstly, glass ceramic composites (GCC), which consist of >50 vol% glass in the starting powder, and, secondly, glass-bonded ceramics (GBC), where glass is added as a sintering aid only. The CTE of GBC is mainly determined by the crystalline component. For GCC, the CTE can be well predicted, if CTE and elastic data of each phase in the microstructure are known. A nonlinear characteristic of the CTE versus phase composition was found with increasing E _crystals/ E _glass ratio and absolute CTE difference between the components. The glass composition and glass amount can be used to compensate the fixed properties of a crystalline material in a desired way. However, because the CTE and permittivity of a glass cannot be chosen independently, an optimum glass composition has to be found. For a given LTCC, it is possible to control the devitrification by shifting the glass composition. In this way, the resulting CTE values can be predicted more exactly and tailoring becomes possible. Different LTCC materials, based on the crystalline compounds Ba(La,Nd)₂Ti₄O₁₂, ZrO₂ (Y-TZP), SiO₂ (quartz), and specially developed glasses, possessing an elevated CTE of around 10 × 10⁻⁶ K⁻¹ while showing permittivity ɛ_r between 6 and 63, are introduced.     

Parenting through change: An effective prevention program for single mothers.

This randomized experimental prevention study (a) evaluated the effectiveness of a parent-training program in a sample of 238 divorcing mothers with sons in Grades 1–3 and (b) provided an experimental test of coercion theory. The intervention produced reductions in observed coercive parenting, prevented decay in positive parenting, and generally improved effective parenting practices in comparisons of mothers in experimental and control groups. Moreover, coercion theory was supported. Improved parenting practices correlated significantly with improvements in teacher-reported school adjustment, child-reported maladjustment, and mother-reported maladjustment. The intervention indirectly benefitted child outcomes through improved parenting practices for a model based on child report and, to a lesser extent, on teacher report. The intervention did not produce direct effects on child outcomes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Association of gastrointestinal illness and recreational water exposure at an inland U.S. beach

Recent epidemiology studies examining U.S. recreational water exposure and illness relationships have focused primarily on coastal and Great Lakes beaches. Human-made lakes in the U.S. have received little attention in epidemiology studies despite contributing to more waterborne disease epidemics annually than coastal U.S. waters. In a comprehensive beach cohort study, we examined relationships between water quality indicators and reported adverse health outcomes among users of a beach at an inland U.S. lake. Human health data was collected over 26 swimming days during the 2009 swimming season in conjunction with water quality measurements. Adverse health outcomes were reported 8-9 days post-exposure via a phone survey. Wading, playing or swimming in the water was observed to be a significant risk factor for GI illness (adjusted odds ratio (AOR) of 3.2; CI 1.1, 9.0). Among water users, Escherichia coli density was significantly associated with elevated GI illness risk where the highest E. coli quartile was associated with an AOR of 7.0 (CI 1.5, 32). GI illness associations are consistent with previous freshwater epidemiology studies. Our findings are unique in that our observations of positive associations with GI illness risk are based upon a single daily E. coli measurement. Lastly, this study focused on an understudied issue, illness risk at inland reservoirs. Our results support the usefulness of E. coli as a health-relevant indicator of water quality for this inland U.S. beach.     

Synthesis and X-ray crystal structure of a bis-cyclometalated phosphorescent red-emitting iridium(III) complex

The synthesis of the bis-cyclometalated complex [{Ir(μ-Cl)(ccpz)₂}₂] (1, cppz = 1-chloro-4-(4-chlorophenyl)-phthalazine) from hydrated iridium(III) chloride and the ligand ccpz in refluxing ethoxyethanol is described. Compound 1 was characterized by spectroscopic means and the crystal structure was determined by X-ray crystallography. The absorption and emission spectra exhibit the new compound as a red-emitting phosphorescent complex.     

Modelling the spread of hepatitis C via commercial tattoo parlours: implications for public health interventions

Hepatitis C (HCV) is a serious infection caused by a blood-borne virus. It is a contagious disease spreading via a variety of transmission mechanisms including contaminated tattoo equipment. Effectively regulating commercial tattoo parlours can greatly reduce this risk. This paper models the cost-effectiveness and optimal timing of such interventions, and parameterises the model with data for Vienna, Austria. This dynamic model of the contagious spread of HCV via tattooing and other mechanisms accounts for secondary infections and shows that regulating tattoo parlours as done in Vienna, Austria in 2003, is a cost-saving intervention.     

Brief group psychoeducation for bulimia nervosa: Assessing the clinical significance of change.

41 women with bulimia nervosa completed a brief intervention that was designed to promote symptom management. Cutoff scores for the determination of reliable and clinically significant change were calculated for several psychometric instruments that are commonly used as outcome measures in the field of eating disorders. Using these statistical procedures to assess therapeutic change, this study documents the diversity of outcomes that individuals reported following their participation in the intervention. As expected, there was a differential reporting of clinically significant change in favor of specific eating psychopathology relative to personality features and associated psychopathology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)