Achieving ultra-low and -uniform residual magnetic fields in a very large magnetically shielded room for fundamental physics experiments

High-precision searches for an electric dipole moment of the neutron (nEDM) require stable and uniform magnetic field environments. We present the recent achievements of degaussing and equilibrating the magnetically shielded room (MSR) for the n2EDM experiment at the Paul Scherrer Institute. We present the final degaussing configuration that will be used for n2EDM after numerous studies. The optimized procedure results in a residual magnetic field that has been reduced by a factor of two. The ultra-low field is achieved with the full magnetic-field-coil system, and a large vacuum vessel installed, both in the MSR. In the inner volume of ∼ 1.4 m 3 , the field is now more uniform and below 300 pT. In addition, the procedure is faster and dissipates less heat into the magnetic environment, which in turn, reduces its thermal relaxation time from 12 h down to 1.5 h .

A large 'Active Magnetic Shield' for a high-precision experiment: nEDM collaboration

We present a novel Active Magnetic Shield (AMS), designed and implemented for the n2EDM experiment at the Paul Scherrer Institute. The experiment will perform a high-sensitivity search for the electric dipole moment of the neutron. Magnetic-field stability and control is of key importance for n2EDM. A large, cubic, 5 m side length, magnetically shielded room (MSR) provides a passive, quasi-static shielding-factor of about 10 5 for its inner sensitive volume. The AMS consists of a system of eight complex, feedback-controlled compensation coils constructed on an irregular grid spanned on a volume of less than 1000 m3 around the MSR. The AMS is designed to provide a stable and uniform magnetic-field environment around the MSR, while being reasonably compact. The system can compensate static and variable magnetic fields up to ± 50 μ T (homogeneous components) and ± 5 μ T/m (first-order gradients), suppressing them to a few μ T in the sub-Hertz frequency range. The presented design concept and implementation of the AMS fulfills the requirements of the n2EDM experiment and can be useful for other applications, where magnetically silent environments are important and spatial constraints inhibit simpler geometrical solutions.

Sympathetic cooling of positrons to cryogenic temperatures for antihydrogen production

The positron, the antiparticle of the electron, predicted by Dirac in 1931 and discovered by Anderson in 1933, plays a key role in many scientific and everyday endeavours. Notably, the positron is a constituent of antihydrogen, the only long-lived neutral antimatter bound state that can currently be synthesized at low energy, presenting a prominent system for testing fundamental symmetries with high precision. Here, we report on the use of laser cooled Be+ ions to sympathetically cool a large and dense plasma of positrons to directly measured temperatures below 7 K in a Penning trap for antihydrogen synthesis. This will likely herald a significant increase in the amount of antihydrogen available for experimentation, thus facilitating further improvements in studies of fundamental symmetries.

P5-01-12: Identification of an ATM Activation Subtype in PTEN Mutant Breast Tumours

Background PTEN is frequently lost in cancer cells through genetic mutation or epigenetic silencing. Loss of PTEN function has been widely reported to cause up-regulation of the PI3K/AKT signalling pathway resulting in increased cell growth, proliferation and survival. More recently it has been reported that PTEN null cells demonstrate genomic instability through increased ROS and oxidative stress induced DNA damage. The aim of this study was to identify a biomarker for PTEN status in human breast cancers.

Materials and Methods A metagene representing ATM activation was generated from public cell line data of AT fibroblasts treated with gamma-irradiation. This was used to perform hierarchical clustering analysis of a public DNA microarray profiling dataset with known PTEN IHC status. The metagene was validated in PTEN wildtype and null breast cancer cell lines.

Results We found that PTEN null cells have elevated levels of ROS and furthermore activation of the DNA damage signalling kinase, ATM. In agreement with this, the ATM metagene signature correlated with PTEN mutation in breast cancer tumours. Scoring of PTEN wildtype and null breast cancer cell lines using the metagene correlated with ATM activation and sensitivity to inhibition of ATM. Furthermore we show that inhibition of ATM caused DNA damage, cell cycle arrest and apoptosis in PTEN deficient cells suggesting a novel therapeutic strategy.

Conclusion These observations suggest that ATM may represent a therapeutic target in PTEN deficient tumours and furthermore ATM activation may also be an important biomarker of PTEN mutation or loss in breast cancer.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-01-12.

Use of skin-cancer prevention strategies among farmers and their spouses

Epidemiologic studies show that farmers are at increased risk of skin cancer, presumed to be secondary to the increased time they spend outdoors with exposure to the sun. We surveyed a random sample of farmers and their spouses 40 years of age or older from four rural counties in Michigan on their knowledge, attitudes, and behavior regarding protection of their skin from the sun and screening medical exams for skin cancer. Questionnaires were completed by 1,342 farmers and their spouses. This was a response rate of 63.5%. Eighty to ninety percent knew the changes in the skin that could indicate cancer and required medical follow-up. Only 40% of the men and 65% of the women were likely to protect their skin when they went outdoors. Increasing age and personal history of skin cancer increased the likelihood of both men and women protecting their skin when they went outside. Additionally, higher-income women were likely to use sun protection. Despite the fact that 90% of the respondents had had a physical examination in the last three years, less than one third reported ever having had their skin examined for cancer. Increasing age, income, and education increased the likelihood of having had such an exam. The majority of those who had had a skin exam had the exam for a particular skin problem, and not as part of a routine physical examination. Farmers and their spouses need to increase their use of sun protection when going outside. Additionally, health care providers need to routinely include examination of the skin for skin cancer and alert their patients that it is being performed.

U.S. farm women's participation in breast cancer screening practices

BACKGROUND

Surveys of women in the general population indicate that women are being screened for breast cancer at a much lower rate than recommended. There has been a concern that women living in rural areas may be screened for breast cancer even less often than women in urban or suburban areas because of reduced access to health practitioners.

METHODS

A random sample of farm women age 40 years or older from 4 rural counties in Michigan was surveyed on knowledge, attitudes, and use of breast cancer screening.

RESULTS

Six hundred eighty farm women completed a questionnaire. This was a response rate of 63.8%. The percentages of farm women who reported ever having had a mammogram, having had a mammogram in the past 3 years, and having had a mammogram in the last year were 80.6, 73.7, and 51.9%, respectively. The frequency of clinical breast examinations parallelled mammography usage at slightly higher percentages. Mammogram usage increased with higher education, income, and insurance coverage. Usage decreased in women age 75 years or older (ever 63.1%, in the last 3 years 58.2%, and in the last year 40.4%). Farm women were generally knowledgeable about symptoms and signs of breast cancer and understood the benefit of screening. There was, however, a range of answers on when to start or stop having a mammogram. Among farm women who reported not having a mammogram recently, the most important reasons were: haven't had any problems (29.4%), wasn't recommended by a doctor (14.3%), and procrastinated (11.3%).

CONCLUSIONS

Farm women in this survey reported having had breast cancer screening at rates similar to or above those in the general population. Because of a limited response rate (63.5%) and the relative affluence of the farming community in the 4 counties surveyed, these results are probably not generalizable to all populations of farm or rural women.

Medical student interest in combined internal medicine-pediatrics

OBJECTIVE

To determine the level of interest in and perceptions of the field of internal medicine-pediatrics among third-year medical students.

DESIGN

A questionnaire was sent to medical students assessing their career choices, how they envision their future practices, the importance of selected professional goals in relation to their career choices, and their impressions of the likelihood of achieving these goals in given medical fields.

SETTING

Two large Midwestern medical schools.

PARTICIPANTS

Medical students at the end of their third year.

INTERVENTIONS

None.

RESULTS

Three hundred of 425 students (70%) participated. One hundred thirty-three students (44%) chose a primary care field as their first choice. Seventy-one (54% of the 133) chose internal medicine-pediatrics as their first, second, or third choice. Students rated the likelihood of achieving certain professional goals by specialty. Internal medicine-pediatrics was ranked almost identically with internal medicine and pediatrics. However, internal medicine-pediatrics differed from family medicine in that it was ranked higher in intellectual stimulation, association with interesting colleagues, attaining a position of leadership, entering a respected profession, and involvement in science and research (p less than 0.0001).

CONCLUSIONS

The field of internal medicine-pediatrics attracts significant interest among medical students and is viewed as similar to internal medicine and less similar to family medicine.