Unfolding the physics of URu2Si2 through silicon to phosphorus substitution

The heavy fermion intermetallic compound URu₂Si₂ exhibits a hidden-order phase below the temperature of 17.5 K, which supports both anomalous metallic behavior and unconventional superconductivity. While these individual phenomena have been investigated in detail, it remains unclear how they are related to each other and to what extent uranium f-electron valence fluctuations influence each one. Here we use ligand site substituted URu₂Si_2-xP_x to establish their evolution under electronic tuning. We find that while hidden order is monotonically suppressed and destroyed for x≤0.035, the superconducting strength evolves non-monotonically with a maximum near x≈0.01 and that superconductivity is destroyed near x≈0.028. This behavior reveals that hidden order depends strongly on tuning outside of the U f-electron shells. It also suggests that while hidden order provides an environment for superconductivity and anomalous metallic behavior, it's fluctuations may not be solely responsible for their progression.

The heavy fermion compound URu₂Si₂ displays a hidden order phase and superconductivity at low temperatures. Here, the authors perform substitution studies—partially replacing silicon with phosphorus—and study the effects on hidden order and superconductivity.

Occupational radiation dose to eyes from interventional radiology procedures in light of the new eye lens dose limit from the International Commission on Radiological Protection

OBJECTIVE

In 2011, the International Commission on Radiological Protection (ICRP) recommended a substantial reduction in the equivalent dose limit for the lens of the eye, in line with a reduced threshold of absorbed dose for radiation-induced cataracts. This is of particular relevance in interventional radiology (IR) where it is well established that staff doses can be significant, however, there is a lack of data on IR eye doses in terms of Hp(3). Hp(3) is the personal dose equivalent at a depth of 3 mm in soft tissue and is used for measuring lens dose. We aimed to obtain a reliable estimate of eye dose to IR operators.

METHODS

Lens doses were measured for four interventional radiologists over a 3-month period using dosemeters specifically designed to measure Hp(3).

RESULTS

Based on their typical workloads, two of the four interventional radiologists would exceed the new ICRP dose limit with annual estimated doses of 31 and 45 mSv to their left eye. These results are for an "unprotected" eye, and for IR staff who routinely wear lead glasses, the dose beneath the glasses is likely to be significantly lower. Staff eye dose normalized to patient kerma-area product and eye dose per procedure have been included in the analysis.

CONCLUSION

Eye doses to IR operators have been established using a dedicated Hp(3) dosemeter. Estimated annual doses have the potential to exceed the new ICRP limit.

ADVANCES IN KNOWLEDGE

We have estimated lens dose to interventional radiologists in terms of Hp(3) for the first time in an Irish hospital setting.

Innovation in immediate neonatal care: development of the Bedside Assessment, Stabilisation and Initial Cardiorespiratory Support (BASICS) trolley

Objective

Babies receive oxygen through their umbilical cord while in the uterus and for a few minutes after birth. Currently, if the baby is not breathing well at birth, the cord is cut so as to transfer the newborn to a resuscitation unit. We sought to develop a mobile resuscitation trolley on which newly born babies can be resuscitated while still receiving oxygenated blood and the ‘placental transfusion’ through the umbilical cord. This would also prevent separation of the mother and baby in the first minutes after birth.

Design

Multidisciplinary iterative product development.

Setting

Clinical Engineering Department of a University Teaching Hospital.

Methods

Following an initial design meeting, a series of prototypes were developed. At each stage, the prototype was reviewed by a team of experts in the laboratory and in the hospital delivery suite to determine ease of use and fitness for purpose. A commercial company was identified to collaborate on the trolley's development and secure marking with the Conformité Européenne mark, allowing the trolley to be introduced into clinical practice.

Results

The trolley is a small mobile resuscitation unit based on the concept of an overbed hospital table. It can be manoeuvred to within 50 cm of the mother's pelvis so that the umbilical cord can remain intact during resuscitation, irrespective of whether the baby is born naturally, by instrumental delivery or by caesarean section. Warmth for the newborn comes from a heated mattress and the trolley has the facility to provide suction, oxygen and air.

Conclusions

This is the first mobile resuscitation device designed specifically to facilitate newborn resuscitation at the bedside and with an intact cord. The next step is to assess its safety, its acceptability to clinicians and parents, and to determine whether it allows resuscitation with an intact cord.

A meta-analysis of Hodgkin lymphoma reveals 19p13.3 TCF3 as a novel susceptibility locus

Recent genome-wide association studies (GWAS) of Hodgkin lymphoma (HL) have identified associations with genetic variation at both HLA and non-HLA loci; however, much of heritable HL susceptibility remains unexplained. Here we perform a meta-analysis of three HL GWAS totaling 1,816 cases and 7,877 controls followed by replication in an independent set of 1,281 cases and 3,218 controls to find novel risk loci. We identify a novel variant at 19p13.3 associated with HL (rs1860661; odds ratio (OR)=0.81, 95% confidence interval (95% CI) = 0.76-0.86, P(combined) = 3.5 × 10(-10)), located in intron 2 of TCF3 (also known as E2A), a regulator of B- and T-cell lineage commitment known to be involved in HL pathogenesis. This meta-analysis also notes associations between previously published loci at 2p16, 5q31, 6p31, 8q24 and 10p14 and HL subtypes. We conclude that our data suggest a link between the 19p13.3 locus, including TCF3, and HL risk.

FELASA recommendations for the health monitoring of mouse, rat, hamster, guinea pig and rabbit colonies in breeding and experimental units

The microbiological quality of experimental animals can critically influence animal welfare and the validity and reproducibility of research data. It is therefore important for breeding and experimental facilities to establish a laboratory animal health monitoring (HM) programme as an integrated part of any quality assurance system. FELASA has published recommendations for the HM of rodent and rabbit colonies in breeding and experimental units (Nicklas et al. Laboratory Animals, 2002), with the intention of harmonizing HM programmes. As stated in the preamble, these recommendations need to be adapted periodically to meet current developments in laboratory animal medicine. Accordingly, previous recommendations have been revised and shall be replaced by the present recommendations. These recommendations are aimed at all breeders and users of laboratory mice, rats, Syrian hamsters, guinea pigs and rabbits as well as diagnostic laboratories. They describe essential aspects of HM, such as the choice of agents, selection of animals and tissues for testing, frequency of sampling, commonly used test methods, interpretation of results and HM reporting. Compared with previous recommendations, more emphasis is put on the role of a person with sufficient understanding of the principles of HM, opportunistic agents, the use of sentinel animals (particularly under conditions of cage-level containment) and the interpretation and reporting of HM results. Relevant agents, testing frequencies and literature references are updated. Supplementary information on specific agents and the number of animals to be monitored and an example of a HM programme description is provided in the appendices.

Practical application of suspension criteria scenarios in general radiography, computed radiography,digital radiography and fluoroscopy

Radiological equipment must be assessed against criteria for acceptability to ensure that it meets the minimum standards for patient safety. This assessment is typically led by a medical physicist with input from radiology staff and the equipment supplier. Equipment that does not meet the criteria requires action and may be suspended from clinical use. European Commission report RP 91 will be revised and replaced as RP 162. It has been drawn up to aid medical physicists with the assessment process and provide guidance on suspension levels. This paper details several cases where the criteria in the proposed RP 162 were applied in general radiography, computed radiography, digital radiography and fluoroscopy. The factors considered by the medical physicist and the outcome of each case are presented. The proposed RP 162 report improves on its predecessor and provides a robust set of criteria for ensuring that patient safety within the EU medical exposures framework is optimised.

Criteria and suspension levels in diagnostic radiology

The EC (European Council) Directive on radiation protection of patients requires that criteria for acceptability of equipment in diagnostic radiology, nuclear medicine and radiotherapy be established throughout the member states. This study reviews the background to this requirement and to its implementation in practice. It notes and considers parallel requirements in the EC medical devices directive and International Electrotechnical Commission standards that it is also important to consider and that both sets of requirements should ideally be harmonised due to the global nature of the equipment industry. The study further reviews the types of criteria that can be well applied for the above purposes, and defines qualitative criteria and suspension levels suitable for application. Both are defined and relationships with other acceptance processes are considered (including acceptance testing at the time of purchase, commissioning and the issue of second-hand equipment). Suspension levels are divided into four types, A, B, C and D, depending on the quality of evidence and consensus they are based on. Exceptional situations involving, for example, new or rapidly evolving technology are also considered. The publication and paper focuses on the role of the holder of the equipment and related staff, particularly the medical physics expert and the practitioner. Advice on how the criteria should be created and implemented is provided for these groups and how this might be coordinated with the supplier. Additional advice on the role of the regulator is provided.

Doses measured using AEC on direct digital radiographic (DDR) X-rays systems: updated results with an RP 162 perspective

As digital technology in diagnostic radiology systems becomes more prevalent, there is a need to provide comparative dose information for these new systems. This is needed in particular for testing the automatic exposure control (AEC) devices on direct digital radiography (DDR) systems as there is no consensus on the receptor dose level in the current guidelines. The new European Commission RP 162 document sets the suspension level for the 'verification of kerma at receptor entrance in computed radiography and DDR systems under AEC' as ≥10 µGy. This document also notes that alternate methodologies are acceptable, and may require adjustment in the suspension level if used. This study provides a range of typical doses under AEC for DDR systems, for a variety measurement methodologies, including that described in RP 162.

Occupational radiation dose to eyes from endoscopic retrograde cholangiopancreatography procedures in light of the revised eye lens dose limit from the International Commission on Radiological Protection

OBJECTIVE

Endoscopic retrograde cholangiopancreatography (ERCP) is a common procedure that combines the use of X-ray fluoroscopy and endoscopy for examination of the bile duct. Published data on ERCP doses are limited, including staff eye dose from ERCP. Occupational eye doses are of particular interest now as the International Commission on Radiological Protection (ICRP) has recommended a reduction in the dose limit to the lens of the eye. The aim of this study was to measure occupational eye doses obtained from ERCP procedures.

METHODS

A new eye lens dosemeter (EYE-D(™), Radcard, Krakow, Poland) was used to measure the ERCP eye dose, H(p)(3), at two endoscopy departments in Ireland. A review of radiation protection practice at the two facilities was also carried out.

RESULTS

The mean equivalent dose to the lens of the eye of a gastroenterologist is 0.01 mSv per ERCP procedure with an undercouch X-ray tube and 0.09 mSv per ERCP procedure with an overcouch X-ray tube. Staff eye dose normalised to patient kerma area product is also presented.

CONCLUSION

Staff eye doses in ERCP have the potential to exceed the revised ICRP limit of 20 mSv per annum when an overcouch X-ray tube is used. The EYE-D dosemeter was found to be a convenient method for measuring lens dose. Eye doses in areas outside of radiology departments should be kept under review, particularly in light of the new ICRP eye dose limit.

ADVANCES IN KNOWLEDGE

Occupational eye lens doses from ERCP procedures have been established using a new commercially available dedicated H(p)(3) dosemeter.

Abstract P1-09-04: Down-regulation of trefoil protein 1(TFF1) in normal breast tissue of postmenopausal women at increased risk for breast cancer on exemestane

Background: Aromatase inhibitors (AI) are effective for breast cancer risk reduction in postmenopausal women. TFF1, also known as pS2, is an estrogen response gene present in normal mammary tissue with increased expression in estrogen receptor positive breast cancer. Previous studies have demonstrated down-regulation of TFF1 and Ki-67, a marker of proliferation, in postmenopausal women with locally advanced breast cancer who receive neoadjuvant AIs. TFF1 and proliferating cell nuclear antigen (PCNA) may serve as biomarkers of effect of AIs in women at increased risk for breast cancer.

Methods: We conducted a single-arm phase II trial of exemestane in women at increased risk for breast cancer and examined the impact on TFF1 and PCNA. Postmenopausal women at increased risk for invasive breast cancer by clinical or histological criteria received 25mg of exemestane daily for 2 years. Subjects were required to have stopped any hormonal medication ≥ 3 months prior to enrollment. Image guided breast biopsies targeting dense breast tissue were performed at baseline and at 12 months. Core specimens were obtained under local anesthesia at each time point from the same area of the breast. One core biopsy sample was formalin-fixed, paraffin-embedded and examined for pathologic abnormalities, as well as TFF1 and PCNA. TFF1 was assessed by intensity of stain (0 to 3+) and percent of cells with any staining; PCNA was assessed by percent of cells staining within the tissue section. The pathologist (B.K.) was blinded to the time of biopsy. Change in intensity and % positive cells were evaluated by paired t-test.

Results: Thirty four subjects underwent both baseline & 12 month breast biopsies. Eight biopsies at baseline and 5 biopsies at 12 months did not contain any ductal or lobular tissue and were not analyzed. Twenty-two subjects had evaluable breast tissue at both time points for TFF1 analysis and 23 subjects for PCNA analysis. No high risk lesions or invasive cancers were identified. Of the baseline specimens, 95.5% were positive for TFF1: 59.1% (13 of 22) were scored as 3+(intense), 31.8% (7 of 22) were 2+(moderate) and 4.5% (1 of 22) were 1+(low). Percent of cells staining for TFF1 ranged from 0 to 20% (median = 1%). After 1 year on exemestane TFF1 intensity decreased in 17 subjects (77.3%), 4 had no change and 1 increased. Mean TFF1 change was −1.32 (95% CI −1.87 to −0.76; p < 0.001). The change in % positive cells for PCNA ranged from −15 to +30% (median = 0%).

Discussion: Assessing tissue biomarkers with repeat core needle biopsies in a phase II prevention trial in high risk women is feasible. Since prevention agents are not universally protective, determining biomarkers of effect may allow tailored therapy. TFF1 is a biologically plausible biomarker of AI activity that was down-regulated in 77% of breast tissue following exemestane therapy. This is the first study to evaluate this tissue marker in the prevention setting. Further study is needed to correlate with other biomarkers of interest, e.g. change in mammographic density, serum hormone levels and clinical outcomes.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-09-04.

P3-11-01: Effects of Exemestane Therapy on the Lipid Profile of Postmenopausal Women with an Elevated Risk of Developing Invasive Breast Cancer

Background: Aromatase inhibitors are effective for breast cancer prevention in postmenopausal women. In the recent MAP.3 study, exemestane significantly reduced invasive breast cancer in postmenopausal women with an elevated risk of developing breast cancer. At 35 months follow up there was no increase risk in cardiovascular events in this study; however, the effects of exemestane use on lipid profiles and cardiovascular health are still unclear.

Methods: We conducted a single-arm phase II trial of exemestane in women at increased risk for breast cancer and examined the impact of exemestane on lipid profiles. Postmenopausal women at high risk for invasive breast cancer (e.g., Gail Model risk ≥ 1.7, a history of lobular neoplasia, atypical ductal hyperplasia, DCIS, or stage I/II breast cancer, or BRCA 1/2 mutation) were given exemestane (25 mg orally daily) for 2 years. Fasting serum total cholesterol, HDL, LDL, triglycerides, and homocysteine were collected at baseline, 3, 12, and 24 months after initiation of exemestane therapy. Apolipoprotein A and B were collected at baseline, 3 and 12 months. Wilcoxon sign ranked test was used to analyze if changes from baseline values differed from zero. The Hochberg p-value adjustment was used to account for multiple hypothesis tests.

Results: Of the 42 women enrolled in the study, 6 dropped out prior to completing 1 year and 1 dropped out prior to completing 2 years of exemestane therapy. Thirty-one women have completed 2 years of exemestane therapy and the remaining 4 are expected to complete 2 years of therapy by January 2012. On average, participants were 58.5 years old, mostly Caucasian (n = 37; 84.1%), and had a BMI of 29.2 kg/m2. A majority (n = 19) of participants were on lipid-lowering medications (14 were taking a statin) or taking fish oil supplements (n =5) prior to starting on the trial and 1 was started on a statin approximately 10 months after starting the trial. There were no significant differences in mean lipid values for each of the 4 assessment points or in the mean change from baseline at 3, 12, and 24 months between patients who were taking lipid-lowering medications and those were not. In unadjusted analyses, change in HDL from baseline was significantly different from zero and decreased from baseline at 3, 12 and 24 months (−8.0 mg/dL, −8.5 mg/dL, and −9.9 mg/dL; All p-values ≤ .001 before and after applying the Hochberg adjustment). Total cholesterol also significantly decreased from baseline at 3 months (−13.6 mg/dL, p = .002) but was no longer significant at 12 and 24 months (−9.6 mg/dL and −11.4 mg/dL, respectively; p-values = .07). The rest of the lipid panel did not significantly change during follow-up.

Discussion: In agreement with previous studies, we found that exemestane causes a significant decrease in HDL and total cholesterol, while leaving the rest of the lipid panel unchanged. Prior studies excluded patients on lipid-lowering medication; half of our participants were taking lipid-lowering medication. It is notable that both women off and on lipid-lowering medication had decreases in HDL. Additional studies are needed to elucidate long-term cardiovascular outcomes in this high risk but otherwise healthy population.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-11-01.

Analysis of Plasma Properties and Deposition of Amorphous Silicon Alloy Solar Cells Using Very High Frequency Glow Discharge

Positive ionic energy distributions in modified very-high-frequency (MVHF) and radio frequency (RF) glow discharges were measured using a retarding field analyzer. The ionic energy distribution for H2 plasma with 75 MHz excitation at a pressure of 0.1 torr has a peak at 22 eV with a half-width of about 6 eV. However, with 13.56 MHz excitation, the peak appears at 37 eV with a much broader half-width of 18 eV. The introduction of SiH4 to the plasma shifts the distribution to lower energy. Increasing the pressure not only shifts the distribution to lower energy but also broadens the distribution. In addition, the ionic current intensity to the substrate is about five times higher for MVHF plasma than for RF plasma. In order to study the effect of ion bombardment, the deposition of a-Si alloy solar cells using MVHF was investigated in detail at different pressures and external biases. Lowering the pressure and negatively biasing the substrate increases ion bombardment energy and results in a deterioration of cell performance. It indicates that ion bombardment is not beneficial for making solar cells using MVHF. By optimizing the deposition conditions, a 10.8% initial efficiency of a-Si/a-SiGe/SiGe triple-junction solar cell was achieved at a deposition rate of 0.6 nm/sec.