In this paper we present the Low Frequency Instrument (LFI), designed and developed as part of the Planck space mission, the ESA programme dedicated to precision imaging of the cosmic microwave background (CMB). Planck-LFI will observe the full sky in intensity and polarisation in three frequency bands centred at 30, 44 and 70 GHz, while higher frequencies (100−850 GHz) will be covered by the HFI instrument. The LFI is an array of microwave radiometers based on state-of-the-art indium phosphide cryogenic HEMT amplifiers implemented in a differential system using blackbody loads as reference signals. The front end is cooled to 20 K for optimal sensitivity and the reference loads are cooled to 4 K to minimise low-frequency noise. We provide an overview of the LFI, discuss the leading scientific requirements, and describe the design solutions adopted for the various hardware subsystems. The main drivers of the radiometric, optical, and thermal design are discussed, including the stringent requirements on sensitivity, stability, and rejection of systematic effects. Further details on the key instrument units and the results of ground calibration are provided in a set of companion papers.

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Alcohol-impaired driving continues to be a major public health concern, particularly among college students. The current study examined whether sociodemographic, behavioral, and cognitive variables predicted alcohol-impaired driving in a sample of college students. Data were collected via telephone interviews from a random sample of undergraduates, ages 18-25 years old, stratified by sex and class in school. Using hierarchical logistic regression analyses (n = 330), results revealed that higher levels of weekly alcohol use, being age 21 or older, and perceived difficulty in obtaining alternative transportation were associated with a greater likelihood of drinking and driving. In addition, perceived likelihood of drinking and driving-related consequences was associated with a lower likelihood of drinking and driving. Knowledge of the .08% per se and zero tolerance laws did not predict alcohol-impaired driving. Findings are discussed in terms of their implications for college media campaigns designed to reduce alcohol-impaired driving.

ABSTRACT. Objective: This article presents an evaluation of Common Ground, a media campaign-supported prevention program featuring increased enforcement, decreased alcohol access, and other environmental management initiatives targeting college student drinking. Method: Phase 1 of the media campaign addressed student resistance to environmentally focused prevention by reporting majority student support for alcohol policy and enforcement initiatives. Phase 2 informed students about state laws, university policies, and environmental initiatives. We conducted student telephone surveys, with samples stratifi ed by gender and year in school, for 4 consecutive years at the intervention campus and 3 years at a comparison campus. We did a series of one-way between-subjects analyses of variance and analyses of covariance, followed by tests of linear trend and planned comparisons. Targeted outcomes included perceptions of enforcement and alcohol availability, alcohol use, and alcohol-impaired driving. We examined archived police reports for student incidents, primarily those resulting from loud parties. Results: There were increases at the intervention campus in students' awareness of formal alcohol-control efforts and perceptions of the alcohol environment, likelihood of apprehension for underage drinking, consequences for alcohol-impaired driving, and responsible alcohol service practices. There were decreases in the perceived likelihood of other students' negative behavior at off-campus parties. Police-reported incidents decreased over time; however, perceived consequences for off-campus parties decreased. No changes were observed for diffi culty fi nding an off-campus party, self-reported alcohol use, or alcohol-impaired driving. Conclusions: The intervention successfully altered perceptions of alcohol enforcement, alcohol access, and the local alcohol environment. This study provides important preliminary information to researchers and practitioners engaged in collaborative prevention efforts in campus communities. (J. Stud. Alcohol Drugs, Supplement No. 16: 96-105, 2009)

We present the calibration and scientific performance parameters of the Planck Low Frequency Instrument (LFI) measured during the ground cryogenic test campaign. These parameters characterise the instrument response and constitute our optimal pre-launch knowledge of the LFI scientific performance. The LFI shows excellent 1/ f stability and rejection of instrumental systematic effects; its measured noise performance shows that LFI is the most sensitive instrument of its kind. The calibration parameters will be updated during flight operations until the end of the mission.