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.

The very large n2EDM magnetically shielded room with an exceptional performance for fundamental physics measurements

We present the magnetically shielded room (MSR) for the n2EDM experiment at the Paul Scherrer Institute, which features an interior cubic volume with each side of length 2.92 m, thus providing an accessible space of 25 m³. The MSR has 87 openings of diameter up to 220 mm for operating the experimental apparatus inside and an intermediate space between the layers for housing sensitive signal processing electronics. The characterization measurements show a remanent magnetic field in the central 1 m³ below 100 pT and a field below 600 pT in the entire inner volume, up to 4 cm to the walls. The quasi-static shielding factor at 0.01 Hz measured with a sinusoidal 2 μT peak-to-peak signal is about 100 000 in all three spatial directions and increases rapidly with frequency to reach 10⁸ above 1 Hz.

The design of the n2EDM experiment: nEDM Collaboration

We present the design of a next-generation experiment, n2EDM, currently under construction at the ultracold neutron source at the Paul Scherrer Institute (PSI) with the aim of carrying out a high-precision search for an electric dipole moment of the neutron. The project builds on experience gained with the previous apparatus operated at PSI until 2017, and is expected to deliver an order of magnitude better sensitivity with provision for further substantial improvements. An overview is of the experimental method and setup is given, the sensitivity requirements for the apparatus are derived, and its technical design is described.

nEDM experiment at PSI: Data-taking strategy and sensitivity of the dataset

We report on the strategy used to optimize the sensitivity of our search for a neutron electric dipole moment at the Paul Scherrer Institute. Measurements were made upon ultracold neutrons stored within a single chamber at the heart of our apparatus. A mercury cohabiting magnetometer together with an array of cesium magnetometers were used to monitor the magnetic field, which was controlled and shaped by a series of precision field coils. In addition to details of the setup itself, we describe the chosen path to realize an appropriate balance between achieving the highest statistical sensitivity alongside the necessary control on systematic effects. The resulting irreducible sensitivity is better than 1 × 10−26e cm. This contribution summarizes in a single coherent picture the results of the most recent publications of the collaboration.

Statistical sensitivity of the nEDM apparatus at PSI to n − n′ oscillations

The neutron and its hypothetical mirror counterpart, a sterile state degenerate in mass, could spontaneously mix in a process much faster than the neutron β-decay. Two groups have performed a series of experiments in search of neutron – mirror-neutron (n − n′) oscillations. They reported no evidence, thereby setting stringent limits on the oscillation time τnn′. Later, these data sets have been further analyzed by Berezhiani et al.(2009–2017), and signals, compatible with n − n′ oscillations in the presence of mirror magnetic fields, have been reported. The Neutron Electric Dipole Moment Collaboration based at the Paul Scherrer Institute performed a new series of experiments to further test these signals. In this paper, we describe and motivate our choice of run configurations with an optimal filling time of 29 s, storage times of 180 s and 380 s, and applied magnetic fields of 10 μT and 20 μT. The choice of these run configurations ensures a reliable overlap in settings with the previous efforts and also improves the sensitivity to test the signals. We also elaborate on the technique of normalizing the neutron counts, making such a counting experiment at the ultra-cold neutron source at the Paul Scherrer Institute possible. Furthermore, the magnetic field characterization to meet the requirements of this n − n′ oscillation search is demonstrated. Finally, we show that this effort has a statistical sensitivity to n − n′ oscillations comparable to the current leading constraints for B′ = 0.

The n2EDM experiment at the Paul Scherrer Institute

We present the new spectrometer for the neutron electric dipole moment (nEDM) search at the Paul Scherrer Institute (PSI), called n2EDM. The setup is at room temperature in vacuum using ultracold neutrons. n2EDM features a large UCN double storage chamber design with neutron transport adapted to the PSI UCN source. The design builds on experience gained from the previous apparatus operated at PSI until 2017. An order of magnitude increase in sensitivity is calculated for the new baseline setup based on scalable results from the previous apparatus, and the UCN source performance achieved in 2016.

Identical and Nonidentical Twins: Risk and Factors Involved in Development of Islet Autoimmunity and Type 1 Diabetes

OBJECTIVE

There are variable reports of risk of concordance for progression to islet autoantibodies and type 1 diabetes in identical twins after one twin is diagnosed. We examined development of positive autoantibodies and type 1 diabetes and the effects of genetic factors and common environment on autoantibody positivity in identical twins, nonidentical twins, and full siblings.

RESEARCH DESIGN AND METHODS

Subjects from the TrialNet Pathway to Prevention Study (N = 48,026) were screened from 2004 to 2015 for islet autoantibodies (GAD antibody [GADA], insulinoma-associated antigen 2 [IA-2A], and autoantibodies against insulin [IAA]). Of these subjects, 17,226 (157 identical twins, 283 nonidentical twins, and 16,786 full siblings) were followed for autoantibody positivity or type 1 diabetes for a median of 2.1 years.

RESULTS

At screening, identical twins were more likely to have positive GADA, IA-2A, and IAA than nonidentical twins or full siblings (all P < 0.0001). Younger age, male sex, and genetic factors were significant factors for expression of IA-2A, IAA, one or more positive autoantibodies, and two or more positive autoantibodies (all P ≤ 0.03). Initially autoantibody-positive identical twins had a 69% risk of diabetes by 3 years compared with 1.5% for initially autoantibody-negative identical twins. In nonidentical twins, type 1 diabetes risk by 3 years was 72% for initially multiple autoantibody-positive, 13% for single autoantibody-positive, and 0% for initially autoantibody-negative nonidentical twins. Full siblings had a 3-year type 1 diabetes risk of 47% for multiple autoantibody-positive, 12% for single autoantibody-positive, and 0.5% for initially autoantibody-negative subjects.

CONCLUSIONS

Risk of type 1 diabetes at 3 years is high for initially multiple and single autoantibody-positive identical twins and multiple autoantibody-positive nonidentical twins. Genetic predisposition, age, and male sex are significant risk factors for development of positive autoantibodies in twins.

Placental pathology associated with small for gestational age infants

Infants with intrauterine growth restriction (IUGR) are at an increased risk of perinatal disease, including death. Many, but not all small for gestational age infants (SGA) have IUGR. Placental disease is an important cause of IUGR, and gross and microscopic examination is critical in explaining such cases. Reports of placentas from infants with a birth weight < 2SD from the mean (approx 3rd centile) born between Jan 2004-Dec 2011 were evaluated. The principal pathology was determined in each case. Where two or more pathologic findings were present, they were ranked as principal and co-existing in terms of severity. There were 69,493 deliveries over the study period. 461 SGA cases were identified. No placenta was available in 44 cases, and 21 cases of known anomalies were excluded, leaving a study group of 396 cases. Pathology potentially causing or contributing to SGA and/or IUGR was identified in 84.1% of cases. Significant co-existing pathology was seen in 88 cases (22%). Placental examination provides key information in understanding abnormal fetal growth.

The Standardization of Uveitis Nomenclature (SUN) Project. Development of a clinical evidence base utilizing informatics tools and techniques

BACKGROUND

Given the recent increased focus on evidence-based medicine, it is critical that diseases and syndromes have accurate and complete descriptions, including standardized and widely accepted terminologies. Standardizing these descriptions and terminologies is necessary to develop tools such as computerized data entry forms and classification criteria. This need is especially true for diseases that are relatively uncommon, such as uveitis.

OBJECTIVES

To develop a standardized and internationally accepted terminology for the field of uveitis.

METHODS

The Standardization of Uveitis Nomenclature (SUN) Working Group (WG) is an international group of 79 uveitis experts from 18 countries and 62 clinical centers. Initial terminology was developed utilizing a "modified" green field approach, which was enhanced through web-based surveys and teleconferences via a "modified" Delphi technique. Terms were mapped provisionally into ontologic dimensions for each syndrome. The Working Group then met and utilized nominal group techniques as a formalized method of finalizing the mappings.

RESULTS

Mapping of terms into dimensions to describe 28 major uveitic diseases was confirmed using nominal group techniques (achieving super-majority consensus) for each of the diseases at a meeting of the entire WG.

CONCLUSIONS

The SUN WG utilized an informatics-based approach to develop a standardized and internationally accepted terminology for the uveitides.

Clinical presentation of adult coeliac disease

The mode of presentation of coeliac disease has been changing to more atypical or silent disease. Few studies described the clinical presentation of adult coeliac disease in Ireland in recent years. We retrospectively collected the clinical data for all patients who had a diagnosis of coeliac disease made in our centre between January 07 and December 08. Forty seven adults, predominantly females (n = 30), had a confirmed diagnosis of coeliac disease made during the study period. In our patient cohort, the presenting symptom was diarrhoea in 19 (40%) patients, while 16 patients (34%) did not have any G.I. symptoms, 10 (21%) presented with anaemia. Females presented at a significantly younger age compared to males, with median ages at diagnosis of 44.5 and 57 years, respectively (p = 0.04). Females also presented more commonly with non G.I. symptoms (p = 0.07). The reasons behind this gender difference need further study.

Profile of sudden death in an adult population (1999-2008)

Sudden death is the sudden and unexpected death of an individual within 24 hours of symptom onset. The vast majority of these cases are found, at autopsy, to be due to underlying ischaemic cardiac disease. We retrospectively reviewed all adult post mortems performed at Beaumont Hospital over a decade (1999-2008). Our aim was to identify all sudden death cases (natural and accidental) and subclassify them according to age profile and organ system involved. We identified 1230 sudden death cases in the review period with 775 (63%) deaths attributable to ischaemic heart disease. The rate of sudden death remained constant over the decade with 663 (54%) deaths occurring in the first five years. Our negative autopsy rate was 2.8% corresponding to 35 cases. This is the first Irish study to retrospectively review all adult sudden deaths within a defined catchment area and analyse them as outlined above.

Non-haemorrhagic subdural collection complicating rupture of a middle cranial fossa arachnoid cyst

Arachnoid cysts are a common incidental finding on routine brain imaging and, for the most part, their presence is uneventful. Occasionally they may be associated with haemorrhage into the subdural compartment. Rarer still is simple rupture of the contents of the arachnoid cyst into the extra-axial space. MRI can help distinguish between these two rare occurrences--an important distinction to make as this may assist in directing the treating clinician toward the most appropriate management plan.

A study of prenatal ultrasound and postnatal magnetic imaging in the diagnosis of central nervous system abnormalities

Accurate prenatal diagnosis of central nervous system (CNS) abnormalities is essential in counselling parents, as they are the most common developmental abnormalities causing considerable mortality. Currently, the standard in prenatal imaging is ultrasound scanning (USS). The introduction of fast acquisition magnetic resonance imaging (MRI) has lead to increased diagnostic confidence and information available for parents. Frequently USS initially identifies CNS abnormalities as ventriculomegaly alone. However, it is known that ventriculomegaly is commonly associated with other CNS pathology, which may adversely affect the prognosis. As MRI has superior soft tissue resolution and can be used at any time postnatally, it is expected to identify disorders of myelination that may result from prenatal ventriculomegaly. This study will evaluate the role of MRI as a postnatal imaging tool in patients that had a prenatal USS diagnosis of isolated ventriculomegaly. This was a retrospective review of patient notes and scan reports. The postnatal MRI study group consisted of 9 patients that had been diagnosed initially with prenatal isolated ventriculomegaly on USS, and followed up with postnatal MRI (cases of spina bifida and Dandy-Walker malformations were excluded). Findings from the scan reports were recorded and analysed. Both MRI and prenatal USS gave the same information in 55.6 % of the patients. In the remaining 44.4 %, MRI added to the information provided by the prenatal USS. An interesting finding was that MRI missed a small fluid-filled cyst and an arachnoid cyst in 2 cases. 55.6 % of patients went on to develop other CNS abnormalities prenatally, whereas 33.3 % showed prenatal regression of VM with no other pathology. 11.1 % showed postnatal persistence of isolated VM. As USS has the advantage of being cheap and easy to perform, it will remain as the primary imaging tool in obstetric care. MRI can provide significant additional information that can affect parent counselling, prenatal intervention, and postnatal management. Postnatally, MRI can give some idea of prognosis by evaluating myelination patterns, which is not possible with USS.

Immunolocalization of 5alpha-reductase isozymes in acne lesions and normal skin

BACKGROUND

Dihydrotestosterone mediates androgen-dependent diseases, such as acne, hirsutism, and androgenetic alopecia. This hormone is produced from testosterone by the 5alpha-reductase enzyme. There are 2 isozymes of 5alpha-reductase (types 1 and 2) that differ in their localization within the body and even within the skin. Activity of the type 1 isozyme predominates in sebaceous glands, where it may be involved in regulation of sebum production. Since specific inhibition of 5alpha-reductase type 1 may represent a novel therapeutic approach to acne, it is important to define the localization of these isozymes in normal sebaceous follicles and acne lesions.

OBSERVATIONS

Skin biopsy specimens were obtained from the backs of 11 subjects: 8 with acne and 3 without acne. Sections of normal follicles, open comedones, closed comedones, and inflammatory lesions were incubated with antibodies to types 1 and 2 5alpha-reductase. In all samples, the type 1 antibody localized specifically to sebaceous glands, and the type 2 antibody localized to the companion layer of the hair follicle (the innermost layer of the outer root sheath) and granular layer of the epidermis. Localization of the type 2 isozyme was also noted within the walls of open and closed comedones and in endothelial cells from sections of inflammatory lesions.

CONCLUSIONS

The immunolocalization of 5alpha-reductase isozymes in normal sebaceous follicles and acne follicles is similar to the pattern described in terminal hair follicles and corresponds with the findings of biochemical studies that have demonstrated predominance of type 1 activity in sebaceous glands. The function of type 2 5alpha-reductase in comedones or endothelial cells in inflammatory lesions is unknown.

Low grade pilocytic astrocytoma presenting as a spontaneous intracerebral haemorrhage in a child

A girl aged 13 years presented with spontaneous intracerebral haemorrhage. Initially, no cause could be found but she was later found to have a low grade pilocytic astrocytoma. This very uncommon presentation was not considered before surgery.

Analysis of protein fractions by micropreparative capillary isoelectric focusing and matrix-assisted laser desorption time-of-flight mass spectrometry

In this study, the use of capillary isoelectric focusing (cIEF) as a micropreparative tool for protein analysis by matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS) is demonstrated. A newly designed, automated, collection interface equipped with a fiber-optic UV detector and a sheath flow connection was employed for collection of protein fractions. Multiple fractions were collected during a single cIEF run and further analyzed by MALDI-TOF-MS for mass assignment. The feasibility of the method was tested with a mixture of model proteins with different isoelectric points and molecular masses, and with variants of human hemoglobins differing in pI, but with negligible difference in M(r). Some practical considerations of the collection procedure and subsequent TOF analysis are presented.

Lidocaine diffusion in five tissue expanders: an in vitro and in vivo study

Previous work in our laboratory has demonstrated that tissue expanders are permeable to lidocaine. In this two-part study, we assessed the in vitro lidocaine diffusion in the following five common tissue expanders: Dow Corning, McGhan, Cox-Uphoff, Hyer-Schulte (Mentor), and Surgitek. In part 1, we demonstrated that wall thickness appeared to be the major determinant for diffusion. Part 2 reports an in vivo study of lidocaine diffusion from tissue expanders used for breast reconstruction. We initially determined that there is incomplete mixing between the valve and connecting tubing and the contents of the expanders, over the period of 1 week. We subsequently examined the lidocaine diffusion from seven tissue expanders placed in a submuscular position for breast reconstruction. The rate of lidocaine diffusion was highly variable, but on average was about 3% per day.

Prevention of posttraumatic pulmonary platelet trapping by portacaval transposition

Significant soft-tissue trauma induces platelet activation, aggregation, and sequestration in the lungs. This pulmonary trapping is due either to the size of the platelet aggregates or to changes in the pulmonary microvasculature. To evaluate which one of these mechanisms is responsible for the trapping, we performed portacaval transposition in one group of pigs, making the liver the first receiving capillary bed for blood from the trauma sites in the lower extremities. One week after the operation, the platelets were labeled with indium oxine and reinfused, and the operated animals and a group of six control animals were subjected to standardized soft-tissue trauma to the lower extremities. Sequestration of platelets in the lungs and in the liver was registered dynamically before and for 90 minutes after the trauma. Soft-tissue trauma induced platelet sequestration in the liver in the operated group (p less than 0.01) and in the lungs in the control group (p less than 0.01). Trapping was paralleled by a decrease in the number of circulating platelets. This study has indicated that posttraumatic pulmonary platelet trapping is caused by platelet activation at the trauma sites and not by changes in the pulmonary microvasculature.

A comparison of xenon-133 clearance with electromagnetic flowmeters and an indicator dilution method for the measurement of liver blood flow

Measurement of liver blood flow has been carried out by three different methods in 14 dogs to assess the accuracy of xenon-133 clearance following portal vein injection. Electromagnetic flowmetry with flow probes on the hepatic artery and portal vein resulted in a mean value of 121.9 +/- 39.3 ml min-1 100 g-1. An indicator dilution study utilizing chromium-51-labelled red cells gave a mean value of 119.4 +/- 31.4 ml min-1 100 g-1 and the xenon-133 clearance following portal vein injection, 120.3 +/- 33.8 ml min-1 100 g-1. One-way analysis of variance showed no statistically significant variation between these three groups. There was a close correlation between xenon-133 clearance and electromagnetic flowmetry and between xenon-133 clearance and the indicator dilution technique. These data suggest that xenon-133 clearance following portal vein injection gives an accurate assessment of liver blood flow and this technique (as well as direct parenchymal injection) can be adapted for clinical use.

Comparison of clinical and hemodynamic assessment of cardiac disability

Clinical versus hemodynamic assessment of cardiac disability was compared in 187 patients with either coronary artery or valvular disease classified using the New York Heart Association classification (excluding class IV). The following variables were analyzed during rest and exercise: arteriovenous oxygen content difference (CavO2), cardiac index (CI), pulmonary artery pressure (PAP), pulmonary artery wedge pressure (PAWP), pulmonary arteriolar resistance index (PARI) and heart rate (HR). 180 comparisons of variables were made. Hemodynamic evaluation paralleled clinical evaluation only 19 times during rest and 12 during exercise. There were 5 instances of clinical and hemodynamic distinction between class I and II, 14 between class I and III and 12 between class II and III. Correlation was best in mitral stenosis. The most useful variable was CI followed by PAP and CavO2. HR was not helpful. This study emphasizes that subjective clinical disability may not correlate with physiologic derangement in certain patients.

Central responses to electrical activation of the peripheral nerves supplying the intrinsic hand muscles

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