Optical spring tracking for enhancing quantum-limited interferometers.

Modern interferometers such as LIGO have achieved sensitivities limited by quantum noise, comprising radiation pressure and shot noise. To mitigate this noise, a static system is employed that minimizes the quantum noise within the measurement band. However, since gravitational wave inspiral signals are a single frequency changing over time, only noise at the chirp frequency needs to be minimized.

Surpassing the Standard Quantum Limit Using an Optical Spring.

Quantum mechanics places noise limits and sensitivity restrictions on physical measurements. The balance between unwanted backaction and the precision of optical measurements imposes a standard quantum limit (SQL) on interferometric systems. In order to realize a sensitivity below the SQL, it is necessary to leverage a backaction evading measurement technique, reduce thermal noise to below the level of backaction, and exploit cancellations of any excess noise contributions at the detector.

Passive laser power stabilization via an optical spring.

Metrology experiments can be limited by the noise produced by the laser involved via small fluctuations in the laser's power or frequency. Typically, active power stabilization schemes consisting of an in-loop sensor and a feedback control loop are employed. Those schemes are fundamentally limited by shot noise coupling at the in-loop sensor.

Resident knowledge of colorectal cancer screening assessed by web-based survey.

Background: To evaluate resident knowledge of colorectal cancer (CRC) screening guidelines and to define areas requiring attention.

Methods: A survey was created using three published guidelines for CRC screening. Program directors for internal medicine residency programs were contacted within the metro New York City area to have their residents participate.

Gastric acid suppression and outcomes in Clostridium difficile infection: a population-based study.

Objective: To evaluate the association of gastric acid suppression medications, including proton pump inhibitors and histamine type 2 blockers, with outcomes in patients with Clostridium difficile infection (CDI) in a population-based cohort.

Patients And Methods: To understand the association between acid suppression and outcomes in patients with CDI, we conducted a population-based study in Olmsted County, Minnesota, from January 1, 1991, through December 31, 2005. We compared demographic data and outcomes, including severe, severe-complicated, and recurrent CDI and treatment failure, in a cohort of patients with CDI who were treated with acid suppression medications with these outcomes in a cohort with CDI that was not exposed to acid-suppressing agents.

The epidemiology of community-acquired Clostridium difficile infection: a population-based study.

Objectives: Clostridium difficile infection (CDI) is a common hospital-acquired infection with increasing incidence, severity, recurrence, and associated morbidity and mortality. There are emerging data on the occurrence of CDI in nonhospitalized patients. However, there is a relative lack of community-based CDI studies, as most of the existing studies are hospital based, potentially influencing the results by referral or hospitalization bias by missing cases of community-acquired CDI.