Book chapters will be unavailable on Saturday 24th August between 8am-12pm BST. This is for essential maintenance which will provide improved performance going forwards. Please accept our apologies for any inconvenience caused.
To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure firstname.lastname@example.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
We evaluated the impact of an electronic health record based 72-hour antimicrobial time-out (ATO) on antimicrobial utilization. We observed that 6 hours after the ATO, 21% of empiric antimicrobials were discontinued or de-escalated. There was a significant reduction in the duration of antimicrobial therapy but no impact on overall antimicrobial usage metrics.
After five positive randomized controlled trials showed benefit of mechanical thrombectomy in the management of acute ischemic stroke with emergent large-vessel occlusion, a multi-society meeting was organized during the 17th Congress of the World Federation of Interventional and Therapeutic Neuroradiology in October 2017 in Budapest, Hungary. This multi-society meeting was dedicated to establish standards of practice in acute ischemic stroke intervention aiming for a consensus on the minimum requirements for centers providing such treatment. In an ideal situation, all patients would be treated at a center offering a full spectrum of neuroendovascular care (a level 1 center). However, for geographical reasons, some patients are unable to reach such a center in a reasonable period of time. With this in mind, the group paid special attention to define recommendations on the prerequisites of organizing stroke centers providing medical thrombectomy for acute ischemic stroke, but not for other neurovascular diseases (level 2 centers). Finally, some centers will have a stroke unit and offer intravenous thrombolysis, but not any endovascular stroke therapy (level 3 centers). Together, these level 1, 2, and 3 centers form a complete stroke system of care. The multi-society group provides recommendations and a framework for the development of medical thrombectomy services worldwide.
Multiple studies have demonstrated that daily chlorhexidine gluconate (CHG) bathing is associated with a significant reduction in infections caused by gram-positive pathogens. However, there are limited data on the effectiveness of daily CHG bathing on gram-negative infections. The aim of this study was to determine whether daily CHG bathing is effective in reducing the rate of gram-negative infections in adult intensive care unit (ICU) patients.
We searched MEDLINE and 3 other databases for original studies comparing daily bathing with and without CHG. Two investigators extracted data independently on baseline characteristics, study design, form and concentration of CHG, incidence, and outcomes related to gram-negative infections. Data were combined using a random-effects model and pooled relative risk ratios (RRs), and 95% confidence intervals (CIs) were derived.
In total, 15 studies (n = 34,895 patients) met inclusion criteria. Daily CHG bathing was not significantly associated with a lower risk of gram-negative infections compared with controls (RR, 0.89; 95% CI, 0.73–1.08; P = .24). Subgroup analysis demonstrated that daily CHG bathing was not effective for reducing the risk of gram-negative infections caused by Acinetobacter, Escherichia coli, Klebsiella, Enterobacter, or Pseudomonas spp.
The use of daily CHG bathing was not associated with a lower risk of gram-negative infections. Further, better designed trials with adequate power and with gram-negative infections as the primary end point are needed.
A significant portion of patients with Clostridium difficile infections (CDI) experience recurrence, and there is little consensus on its treatment. With the availability of newer agents for CDI and the added burdens of recurrent disease, a cost-effectiveness analysis may provide insight on the most efficient use of resources.
A decision-tree analysis was created to compare the cost-effectiveness of 3 possible treatments for patients with first CDI recurrence: oral vancomycin, fidaxomicin, or bezlotoxumab plus vancomycin. The model was performed from a payer’s perspective with direct cost inputs and a timeline of 1 year. A systematic review of literature was performed to identify clinical, utility, and cost data. Quality-adjusted life years (QALY) and incremental cost-effectiveness ratios were calculated. The willingness-to-pay (WTP) threshold was set at $100,000 per QALY gained. The robustness of the model was tested using one-way sensitivity analyses and probabilistic sensitivity analysis.
Vancomycin had the lowest cost ($15,692) and was associated with a QALY gain of 0.8019 years. Bezlotoxumab plus vancomycin was a dominated strategy. Fidaxomicin led to a higher QALY compared to vancomycin, at an incremental cost of $500,975 per QALY gained. Based on our WTP threshold, vancomycin alone was the most cost-effective regimen for treating the first recurrence of CDI. Sensitivity analyses demonstrated the model’s robustness.
Vancomycin alone appears to be the most cost-effective regimen for the treatment of first recurrence of CDI. Fidaxomicin alone led to the highest QALY gained, but at a cost beyond what is considered cost-effective.
Introduction: Emergency Department (ED) staff burnout correlates with psychological coping strategies used by Emergency department health professionals (EDHPs). Staff at two urban referral EDs in New Brunswick took part in a survey of burnout and coping strategies after one ED experienced an influx of new physicians and a newly renovated ED in 2011. Six years later, ED crowding and EDHP staffing problems became prevalent at both EDs. We compared levels of burnout at two urban referral EDs to determine if burnout and coping worsened over time. Methods: An anonymous survey of all EDHPs at 2 urban referral EDs was performed in 2011 and in 2017. A demographics questionnaire, the Maslach Burnout Inventory (MBI, measuring emotional exhaustion, depersonalization and personal accomplishment), and the Coping Inventory for Stressful Situations (CISS, measuring task-oriented, emotion-oriented, and avoidance-oriented coping styles) were collected. Descriptive statistics and linear regression models examined relationships over time and between the two hospitals. Results: Burnout scores were similar both at the two facilities and in 2011 (n=153) and 2017 (n=127). There were no differences between samples or EDs for important factors. Emotion-oriented coping was associated with higher levels of burnout, while task-oriented coping was inversely correlated with burnout. Experiencing professional stress was a significant predictor of emotional exhaustion, while those working longer years in their current department had higher emotional exhaustion and depersonalization. By 2017, both EDs had experienced significant nursing staff turnover (50%) compared to 2011. Conclusion: Burnout scores remained consistent after 6 years at these two urban referral EDs. Given the evidence that increased years of service is associated with increased burnout, high staff turnover rate at both EDs could explain how scores remained constant. Staff turnover may represent a way these ED systems cope in a challenging environment. In 2017, task-oriented copers continued to score lower while emotionally-oriented copers showed higher burnout risk, and experiencing professional stress remains a strong predictor of burnout.
Contaminated hands of healthcare workers (HCWs) are an important source of transmission of healthcare-associated infections. Alcohol-based hand sanitizers, while effective, do not provide sustained antimicrobial activity. The objective of this study was to compare the immediate and persistent activity of 2 hand hygiene products (ethanol [61% w/v] plus chlorhexidine gluconate [CHG; 1.0% solution] and ethanol only [70% v/v]) when used in an intensive care unit (ICU).
Prospective, randomized, double-blinded, crossover study
Three ICUs at a large teaching hospital
In total, 51 HCWs involved in direct patient care were enrolled in and completed the study.
All HCWs were randomized 1:1 to either product. Hand prints were obtained immediately after the product was applied and again after spending 4–7 minutes in the ICU common areas prior to entering a patient room or leaving the area. The numbers of aerobic colony-forming units (CFU) were compared for the 2 groups after log transformation. Each participant tested the alternative product after a 3-day washout period.
On bare hands, use of ethanol plus CHG was associated with significantly lower recovery of aerobic CFU, both immediately after use (0.27 ± 0.05 and 0.88 ± 0.08 log10 CFU; P = .035) and after spending time in ICU common areas (1.81 ± 0.07 and 2.17 ± 0.05 log10 CFU; P<.0001). Both the antiseptics were well tolerated by HCWs.
In comparison to the ethanol-only product, the ethanol plus CHG sanitizer was associated with significantly lower aerobic bacterial counts on hands of HCWs, both immediately after use and after spending time in ICU common areas.
There is limited evidence on the prevalence and identification of antenatal mental disorders.
To investigate the prevalence of mental disorders in early pregnancy and the diagnostic accuracy of depression-screening (Whooley) questions compared with the Edinburgh Postnatal Depression Scale (EPDS), against the Structured Clinical Interview DSM-IV-TR.
Cross-sectional survey of women responding to Whooley questions asked at their first antenatal appointment. Women responding positively and a random sample of women responding negatively were invited to participate.
Population prevalence was 27% (95% CI 22–32): 11% (95% CI 8–14) depression; 15% (95% CI 11–19) anxiety disorders; 2% (95% CI 1–4) obsessive–compulsive disorder; 0.8% (95% CI 0–1) post-traumatic stress disorder; 2% (95% CI 0.4–3) eating disorders; 0.3% (95% CI 0.1–1) bipolar disorder I, 0.3% (95% CI 0.1–1%) bipolar disorder II; 0.7% (95% CI 0–1) borderline personality disorder. For identification of depression, likelihood ratios were 8.2 (Whooley) and 9.8 (EPDS). Diagnostic accuracy was similar in identifying any disorder (likelihood ratios 5.8 and 6).
Endorsement of Whooley questions in pregnancy indicates the need for a clinical assessment of diagnosis and could be implemented when maternity professionals have been appropriately trained on how to ask the questions sensitively, in settings where a clear referral and care pathway is available.
Declaration of interest
L.M.H. chaired the National Institute for Health and Care Excellence CG192 guidelines development group on antenatal and postnatal mental health in 2012–2014.
Ultrasound imaging has proved a very useful tool for the modern animal breeder wishing to improve carcass composition. However, more accurate imaging technologies, such as X-ray Computer Tomography (CT), could accelerate genetic improvement of carcass composition, and widen the range of traits assessed (e.g. by considering deeper tissues). Carcass quality is assuming more importance for breeders but quality traits are difficult to assess objectively and accurately in live sheep. The present study was designed to identify a few CT scan positions from which accurate prediction of dissected tissue weights could be made in meat sheep.
One hundred Suffolk lambs (50 of each sex) were CT scanned and slaughtered at 14, 18, 22 or 26 weeks of age (59±16kg LW, range 20-96kg). Each animal was scanned at seven sites; three in the gigot (ISC, caudal ischium; FEM, mid-shaft of femur; HIP, hip joint), two in the loin (LV5 and LV2, 5th and 2nd lumbar vertebrae) and two in the chest/ shoulder (TV8 and TV6, 8th and 6th thoracic vertebrae).
Early in the 1980s a selection index was designed at SAC to improve the rate of lean growth in terminal sire sheep which combined ultrasound measurements of fat and muscle depth, and live weight at 150 days of age (Simm and Dingwall, 1989). Beginning in 1985, this index was applied in the SAC Suffolk flock in a performance test. In 1994, rams from a line selected on this index weighed on average 12% more (8 kg) and had 12% lower fat depth (– 0.9 mm) and 10% higher muscle depth (2.9 mm) than rams from an unselected Control line. Comparison of Selection and Control line animals has thus far been based on live predictors of carcass composition at weights substantially heavier than typical market lamb weights. The aims of this study were to test whether selection decisions based on the lean growth index produced an improvement in actual carcass composition in purebred terminal sire sheep and whether these changes persisted at live weights different from those under which selection was carried out.
Breeding leaner sheep is a desirable goal provided reductions in fatness do not compromise survival and productivity, particularly in harsh environments. Whether some energy stores are more labile than others, the internal fat depots in particular, is not clear. Genetic variation in this trait could be usefully exploited in hill sheep where carcass fat is undesirable but energy reserves are important. Patterns of change in body energy stores need to be examined to determine when it is best to assess energy stores in animals. X-ray computer tomography (CT) provides a means to examine depletion and repletion of body energy but scans are not cheap. In order to use CT in a cost effective way, a number of variables need to be assessed from just a few scans. This report presents results of a study designed to define such a scanning approach in terms of which scans were most informative and which produced most accurate predictions of tissue size.
There is increasing interest in the use of red clover (Trifolium pratense) as a high protein forage crop to finish growing lambs. Red clover contains the isoflavanoid compound formononetin which is converted to the non-steroidal oestrogen analogue equol by rumen micro-organisms. Equol is absorbed by the animal, and can have significant effects, such as suppressing reproductive cycling in ewes. Very few commercial red clover varieties have been bred with a low formononetin content to prevent this problem. Although human health benefits have been linked to the consumption of oestrogenically active compounds in foods such as soya (Kurzer and Xu, 1997), there is a need to investigate the presence of oestrogenically active compounds in animal products. The objective of this study was to investigate plasma metabolite and hormone concentrations, and the residual levels of equol in meat, of lambs grazing two varieties of red clover differing in their formononetin contents, compared to control animals grazing grass.
Introduction: Point of care ultrasonography (PoCUS) is an established tool in the initial management of hypotensive patients in the emergency department (ED). It has been shown rule out certain shock etiologies, and improve diagnostic certainty, however evidence on benefit in the management of hypotensive patients is limited. We report the findings from our international multicenter RCT assessing the impact of a PoCUS protocol on diagnostic accuracy, as well as other key outcomes including mortality, which are reported elsewhere. Methods: Recruitment occurred at 4 North American and 3 Southern African sites. Screening at triage identified patients (SBP<100 mmHg or shock index >1) who were randomized to either PoCUS or control groups. Scans were performed by PoCUS-trained physicians. Demographics, clinical details and findings were collected prospectively. Initial and secondary diagnoses were recorded at 0 and 60 minutes, with ultrasound performed in the PoCUS group prior to secondary assessment. Final chart review was blinded to initial impressions and PoCUS findings. Categorical data was analyzed using Fishers two-tailed test. Our sample size was powered at 0.80 (α:0.05) for a moderate effect size. Results: 258 patients were enrolled with follow-up fully completed. Baseline comparisons confirmed effective randomization. The perceived shock category changed more frequently in the PoCUS group 20/127 (15.7%) vs. control 7/125 (5.6%); RR 2.81 (95% CI 1.23 to 6.42; p=0.0134). There was no significant difference in change of diagnostic impression between groups PoCUS 39/123 (31.7%) vs control 34/124 (27.4%); RR 1.16 (95% CI 0.786 to 1.70; p=0.4879). There was no significant difference in the rate of correct category of shock between PoCUS (118/127; 93%) and control (113/122; 93%); RR 1.00 (95% CI 0.936 to 1.08; p=1.00), or for correct diagnosis; PoCUS 90/127 (70%) vs control 86/122 (70%); RR 0.987 (95% CI 0.671 to 1.45; p=1.00). Conclusion: This is the first RCT to compare PoCUS to standard care for undifferentiated hypotensive ED patients. We found that the use of PoCUS did change physicians’ perceived shock category. PoCUS did not improve diagnostic accuracy for category of shock or diagnosis.
Introduction: Almost every domain of quality is reduced in crowded emergency departments (ED), with significant challenges around the definition, measurement and interventions for ED crowding. We wished to determine if a combination of 3 easily measurable variables could perform as well as standard tools (NEDOCS score and a NEDOCS-derived LOCAL tool) in predicting ED crowding at a tertiary hospital with 57,000 visits per year. Methods: Over a 2-week period, we recorded ED crowding predictor variables and calculated NEDOCS and LOCAL scores. These were compared every 2 hours to a reference standard Physician Visual Analog Scale (range 0 to 10) impression of crowding to determine if any combination of variables outperformed NEDOCS and LOCAL (crowded=5 or greater). Five numeric variables performed well under univariate analysis: i) Total ED Patients; ii) Patients in ED beds + Waiting Room; iii) Boarded Patients; iv) Waiting Room Patients; v) Patients in beds To Be Seen. These underwent multivariate, log regression with stratification and bootstrapping to account for incomplete data and seasonal and daily effect. Results: 143 out of a possible 168 observations were completed. Two different combinations of 3 variables outperformed NEDOCS and LOCAL. The most powerful combination was: Boarded Patients; plus Waiting Room Patients; plus Patients in beds To Be Seen, with Sensitivity 81% and Specificity 76% (r=0.844, β=0.712, p<0.0001, strong positive correlation). This compared favourably with NEDOCS and LOCAL, each with Sensitivity 71% and Specificity 64%[PA1] (r=0.545 and r=0.640 respectively). We will also present a sensitivity and specificity analysis of all combinations of predictor variables, using various reference standard cut-offs for crowding. Conclusion: A combination of 3 easily measurable ED variables (Boarded Patients; plus Waiting Room Patients; plus Patients in beds To Be Seen) performed better than the validated NEDOCS tool and a NEDOCS-derived LOCAL score at predicting ED crowding. Work is on going to design a simple tool that can predict crowding in real time and facilitate early interventions. Correlation with ED system and clinical outcomes should be studied in different ED environments.
Introduction: Point of care ultrasound (PoCUS) is an established tool in the initial management of patients with undifferentiated hypotension in the emergency department (ED). While PoCUS protocols have been shown to improve early diagnostic accuracy, there is little published evidence for any mortality benefit. We report the findings from our international multicenter randomized controlled trial, assessing the impact of a PoCUS protocol on survival and key clinical outcomes. Methods: Recruitment occurred at 7 centres in North America (4) and South Africa (3). Scans were performed by PoCUS-trained physicians. Screening at triage identified patients (SBP<100 or shock index>1), randomized to PoCUS or control (standard care and no PoCUS) groups. Demographics, clinical details and study findings were collected prospectively. Initial and secondary diagnoses were recorded at 0 and 60 minutes, with ultrasound performed in the PoCUS group prior to secondary assessment. The primary outcome measure was 30-day/discharge mortality. Secondary outcome measures included diagnostic accuracy, changes in vital signs, acid-base status, and length of stay. Categorical data was analyzed using Fishers test, and continuous data by Student T test and multi-level log-regression testing. (GraphPad/SPSS) Final chart review was blinded to initial impressions and PoCUS findings. Results: 258 patients were enrolled with follow-up fully completed. Baseline comparisons confirmed effective randomization. There was no difference between groups for the primary outcome of mortality; PoCUS 32/129 (24.8%; 95% CI 14.3-35.3%) vs. Control 32/129 (24.8%; 95% CI 14.3-35.3%); RR 1.00 (95% CI 0.869 to 1.15; p=1.00). There were no differences in the secondary outcomes; ICU and total length of stay. Our sample size has a power of 0.80 (α:0.05) for a moderate effect size. Other secondary outcomes are reported separately. Conclusion: This is the first RCT to compare PoCUS to standard care for undifferentiated hypotensive ED patients. We did not find any mortality or length of stay benefits with the use of a PoCUS protocol, though a larger study is required to confirm these findings. While PoCUS may have diagnostic benefits, these may not translate into a survival benefit effect.
Introduction: Point of Care Ultrasound (PoCUS) protocols are commonly used to guide resuscitation for emergency department (ED) patients with undifferentiated non-traumatic hypotension. While PoCUS has been shown to improve early diagnosis, there is a minimal evidence for any outcome benefit. We completed an international multicenter randomized controlled trial (RCT) to assess the impact of a PoCUS protocol on key resuscitation markers in this group. We report diagnostic impact and mortality elsewhere. Methods: The SHoC-ED1 study compared the addition of PoCUS to standard care within the first hour in the treatment of adult patients presenting with undifferentiated hypotension (SBP<100 mmHg or a Shock Index >1.0) with a control group that did not receive PoCUS. Scans were performed by PoCUS-trained physicians. 4 North American, and 3 South African sites participated in the study. Resuscitation outcomes analyzed included volume of fluid administered in the ED, changes in shock index (SI), modified early warning score (MEWS), venous acid-base balance, and lactate, at one and four hours. Comparisons utilized a T-test as well as stratified binomial log-regression to assess for any significant improvement in resuscitation amount the outcomes. Our sample size was powered at 0.80 (α:0.05) for a moderate effect size. Results: 258 patients were enrolled with follow-up fully completed. Baseline comparisons confirmed effective randomization. There was no significant difference in mean total volume of fluid received between the control (1658 ml; 95%CI 1365-1950) and PoCUS groups (1609 ml; 1385-1832; p=0.79). Significant improvements were seen in SI, MEWS, lactate and bicarbonate with resuscitation in both the PoCUS and control groups, however there was no difference between groups. Conclusion: SHOC-ED1 is the first RCT to compare PoCUS to standard of care in hypotensive ED patients. No significant difference in fluid used, or markers of resuscitation was found when comparing the use of a PoCUS protocol to that of standard of care in the resuscitation of patients with undifferentiated hypotension.
Introduction: Point of care ultrasound (US) is a key adjunct in the management of trauma patients, in the form of the extended focused assessment with sonography in trauma (E-FAST) scan. This study assessed the impact of adding an edus2 ultrasound simulator on the diagnostic capabilities of resident and attending physicians participating in simulated trauma scenarios. Methods: 12 residents and 20 attending physicians participated in 114 trauma simulations utilizing a Laerdal 3G mannequin. Participants generated a ranked differential diagnosis list after a standard assessment, and again after completing a simulated US scan for each scenario. We compared reports to determine if US improved diagnostic performance over a physical exam alone. Standard statistical tests (χ2 and Student t tests) were performed. The research team was independent of the edus2 designers. Results: Primary diagnosis improved significantly from 53 (46%) to 97 (85%) correct diagnoses with the addition of simulated US (χ2=37.7, 1df; p=<0.0001). Of the 61 scenarios where an incorrect top ranked diagnosis was given, 51 (84%) improved following US. Participants were assigned a score from 1 to 5 based on where the correct diagnosis was ranked, with a 5 indicating a correct primary diagnosis. Median scores significantly increased from 3.8 (IQR 3, 4.9) to 5 (IQR 4.7, 5; W=219, p<0.0001).Participants were significantly more confident in their diagnoses after using the US simulator, as shown by the increase in their mean confidence in the correct diagnosis from 53.1% (SD 22.8) to 83.5% (SD 19.1; t=9.0; p<0.0001)Additionally, participants significantly narrowed their differential diagnosis lists from an initial medium count of 3.5 (IQR 2.9, 4.4) possible diagnoses to 2.4 (IQR 1.9, 3; W=-378, p<0.0001) following US. The performance of residents was compared to that of attending physicians for each of the above analyses. No differences in performance were detected. Conclusion: This study showed that the addition of ultrasound to simulated trauma scenarios improved the diagnostic capabilities of resident and attending physicians. Specifically, participants improved in diagnostic accuracy, diagnostic confidence, and diagnostic precision. Additionally, we have shown that the edus2 simulator can be integrated into high fidelity simulation in a way that improves diagnostic performance.
Catheter-associated urinary tract infections (CAUTIs) are among the most common hospital-acquired infections (HAIs). Reducing CAUTI rates has become a major focus of attention due to increasing public health concerns and reimbursement implications.
To implement and describe a multifaceted intervention to decrease CAUTIs in our ICUs with an emphasis on indications for obtaining a urine culture.
A project team composed of all critical care disciplines was assembled to address an institutional goal of decreasing CAUTIs. Interventions implemented between year 1 and year 2 included protocols recommended by the Centers for Disease Control and Prevention for placement, maintenance, and removal of catheters. Leaders from all critical care disciplines agreed to align routine culturing practice with American College of Critical Care Medicine (ACCCM) and Infectious Disease Society of America (IDSA) guidelines for evaluating a fever in a critically ill patient. Surveillance data for CAUTI and hospital-acquired bloodstream infection (HABSI) were recorded prospectively according to National Healthcare Safety Network (NHSN) protocols. Device utilization ratios (DURs), rates of CAUTI, HABSI, and urine cultures were calculated and compared.
The CAUTI rate decreased from 3.0 per 1,000 catheter days in 2013 to 1.9 in 2014. The DUR was 0.7 in 2013 and 0.68 in 2014. The HABSI rates per 1,000 patient days decreased from 2.8 in 2013 to 2.4 in 2014.
Effectively reducing ICU CAUTI rates requires a multifaceted and collaborative approach; stewardship of culturing was a key and safe component of our successful reduction efforts.
This paper presents the results of a preliminary investigation into the problems in through-the-atmosphere image restoration which are more suited to data from a small telescope, i.e., one having a diameter of about 0.5 m, using techniques of image geometric transformation (and eventually, parallel image processing) in their solution. We have imaged bright objects, over fields of view which subtend angles greater than those in most “large” telescope experiments, i.e., between 40 and 100 arc sec, for example, where the isoplanatic assumptions are less valid.
We describe an X-ray polarimeter which will be flown on the SPECTRUM-X-Gamma mission. The instrument exploits three distinct physical processes to measure polarization: Bragg reflection from a graphite crystal, Thomson scattering from a metallic lithium target, and photoemission from a Cesium Iodide photocathode. These three processes allow polarization measurements over an energy band of 0.3 keV to 12 keV. The polarimeter will make possible sensitive measurements of several hundred known X-ray sources. X-ray polarization measurements will allow us to constrain the geometry of gas flow in X-ray binaries, identify nonthermal emission in supernova remnants, test current models for X-ray emission in radio pulsars, determine the radiation mechanisms in active galactic nuclei, and search for inertial frame dragging (Lense-Thirring effect) around the putative black hole in Cygnus X-1.