Fabrication of X-ray Microcalorimeter Focal Planes Composed of Two Distinct Pixel Types

We are developing superconducting transition-edge sensor (TES) microcalorimeter focal planes for versatility in meeting specifications of X-ray imaging spectrometers including high count-rate, high energy resolution, and large field-of-view. In particular, a focal plane composed of two sub-arrays: one of fine-pitch, high count-rate devices and the other of slower, larger pixels with similar energy resolution, offers promise for the next generation of astrophysics instruments, such as the X-ray Integral Field Unit (X-IFU) instrument on the European Space Agency's Athena mission. We have based the sub-arrays of our current design on successful pixel designs that have been demonstrated separately. Pixels with an all gold X-ray absorber on 50 and 75 micron scales where the Mo/Au TES sits atop a thick metal heatsinking layer have shown high resolution and can accommodate high count-rates. The demonstrated larger pixels use a silicon nitride membrane for thermal isolation, thinner Au and an added bismuth layer in a 250 micron square absorber. To tune the parameters of each sub-array requires merging the fabrication processes of the two detector types. We present the fabrication process for dual production of different X-ray absorbers on the same substrate, thick Au on the small pixels and thinner Au with a Bi capping layer on the larger pixels to tune their heat capacities. The process requires multiple electroplating and etching steps, but the absorbers are defined in a single ion milling step. We demonstrate methods for integrating heatsinking of the two types of pixel into the same focal plane consistent with the requirements for each sub-array, including the limiting of thermal crosstalk. We also discuss fabrication process modifications for tuning the intrinsic transition temperature (T_c) of the bilayers for the different device types through variation of the bilayer thicknesses. The latest results on these "hybrid" arrays will be presented.

Study of the Dependency on Magnetic Field and Bias Voltage of an AC-Biased TES Microcalorimeter

At SRON we are studying the performance of a Goddard Space Flight Center single pixel TES microcalorimeter operated in an AC bias configuration. For x-ray photons at 6 keV the pixel shows an x-ray energy resolution ΔE_FWHM =3.7 eV, which is about a factor 2 worse than the energy resolution observed in an identical DC-biased pixel. In order to better understand the reasons for this discrepancy we characterised the detector as a function of temperature, bias working point and applied perpendicular magnetic field. A strong periodic dependency of the detector noise on the TES AC bias voltage is measured. We discuss the results in the framework of the recently observed weak-link behaviour of a TES microcalorimeter.

Altered vitamin E status in Niemann-Pick type C disease

Vitamin E (α-tocopherol) is the major lipid-soluble antioxidant in many species. Niemann-Pick type C (NPC) disease is a lysosomal storage disorder caused by mutations in the NPC1 or NPC2 gene, which regulates lipid transport through the endocytic pathway. NPC disease is characterized by massive intracellular accumulation of unesterified cholesterol and other lipids in lysosomal vesicles. We examined the roles that NPC1/2 proteins play in the intracellular trafficking of tocopherol. Reduction of NPC1 or NPC2 expression or function in cultured cells caused a marked lysosomal accumulation of vitamin E in cultured cells. In vivo, tocopherol significantly accumulated in murine Npc1-null and Npc2-null livers, Npc2-null cerebella, and Npc1-null cerebral cortices. Plasma tocopherol levels were within the normal range in Npc1-null and Npc2-null mice, and in plasma samples from human NPC patients. The binding affinity of tocopherol to the purified sterol-binding domain of NPC1 and to purified NPC2 was significantly weaker than that of cholesterol (measurements kindly performed by R. Infante, University of Texas Southwestern Medical Center, Dallas, TX). Taken together, our observations indicate that functionality of NPC1/2 proteins is necessary for proper bioavailability of vitamin E and that the NPC pathology might involve tissue-specific perturbations of vitamin E status.

A Modelling and Experimental Study for Long-Term Prediction of Localised Corrosion in Carbon Steel Overpacks for High-Level Radioactive Waste

This paper describes a joint modelling and experimental study for investigation of pit growth in carbon steel High-Level Radioactive Waste overpacks under consideration in Japan. A mathematical model of the growth of corrosion pits in metals has been developed. This model is implemented in the computer program CAMLE, and includes representation of the chemical, electrochemical and migration processes that control pit-growth rates. Experiments to provide key input data for the model are described, in addition to experiments to measure ‘short-term’ pit growth. Predictions from the model are compared with these data. Overall, the comparisons are encouraging and the model shows good potential as a tool for assessment of the long-term corrosion behaviour of overpacks under repository conditions. Future developments of the model to improve agreement are discussed.

Results of endoscopic surgery and intralesional steroid therapy for airway compromise due to tracheobronchial Wegener's granulomatosis

BACKGROUND

Upper airway compromise due to tracheobronchial stenosis commonly occurs in patients with Wegener's granulomatosis (WG). There is at present no consensus on the optimal management of this life threatening condition.

OBJECTIVE

To assess the results of laryngo-tracheo-bronchoscopy, intralesional steroid therapy, laser surgery and dilatation in managing obstructive tracheobronchial WG.

METHODS

Records of 18 previously untreated stridulous patients with obstructive tracheobronchial WG, treated between 2004 and 2006, were prospectively recorded on an airway database and retrospectively reviewed. Information about patient and lesion characteristics and treatment details were recorded. Treatment progress was illustrated using a timeline plot, and intervention-free intervals were calculated with actuarial analysis.

RESULTS

There were nine males and the average age at presentation was 40 (16) years (range 13-74). There were 13 patients with tracheal and five with tracheal and bronchial lesions. The average tracheal lesion height was 8 (3) mm, located 23 (9) mm below the glottis. There were 1, 10 and 7 Myer-Cotton grade I, II and III lesions, respectively. Mean intervention-free interval following minimally invasive treatment was 26 (2.8) months. Following endobronchial therapy, the median intervention-free interval was 22 months (p>0.8 vs tracheal lesions). No patient required a tracheostomy or endoluminal stenting.

CONCLUSIONS

Intralesional steroid therapy and conservative endoluminal surgery is an effective strategy for treating airway compromise due to active tracheal and bronchial WG, obviating the need for airway bypass or stenting. We recommend the combination of endotracheal dilatation, conservative laser surgery and steroid therapy as the standard of care for treating airway compromise due to obstructive tracheobronchial WG.

Haemodynamic instability during thyroid surgery: a baroreflex-mediated neurogenic phenomenon?

We present a case of marked intra-operative blood pressure instability in a euthyroid, fit 33-year-old female undergoing elective hemithyroidectomy. This led to significant haemodynamic compromise, cardiac failure and end-organ damage. There was no evidence of a vasoactive endocrine cause, and the nature and timing of the event strongly pointed towards baroreflex-mediated neurogenic sympathetic dysfunction. This can occur during carotid surgery and neck dissection. Although haemodynamic fluctuations may happen during thyroid surgery, their severity in this case was unusual. We believe this could have been a rebound phenomenon in response to acute decompression of the carotid artery which had been compressed by an enlarging cyst. We suggest that in similar cases blockade of the carotid sinus could attenuate such responses.

Extraction and characterization of adenovirus proteins from sodium dodecylsulfate polyacrylamide gel electrophoresis by matrix-assisted laser desorption/ionization mass spectrometry

A new methodology for the extraction and characterization of proteins from Coomassie-stained sodium dodecylsulfate polyacrylamide gel electrophoresis using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) has been described. The utility of this methodology was demonstrated in the characterization of adenovirus proteins. The key steps in the extraction and destaining process involve washing the excised band with a combination of solvents that include 10% acetic acid, acetonitrile, methanol, and formic acid:water:isopropanol mixture. By using this procedure, we determined adenovirus proteins with molecular weights ranging from 10,000 to 110,000 Da by MALDI-MS, obtaining a detection limit of approximately 6 pmol. Parallel experiments were successfully carried out to analyze adenovirus proteins from Cu-stained gels. It was observed that increase in laser intensity resulted in significant improvements in the quality of MALDI mass spectra for the analysis of inefficiently destained proteins from Cu-stained gels.

Critical analysis of intravenous immunoglobulin therapy for recurrent miscarriage

Critical analysis of intravenous immunoglobulin therapy for recurrent miscarriage An alloimmune abnormality is believed to be the cause of recurrent miscarriage in couples in whom no other cause can be identified. Because of its immunosuppressive properties, intravenous immunoglobulin (IVIG) is used as a treatment for this disorder. The purpose of this study was to determine whether IVIG improves the chance of successful pregnancy in women with recurrent miscarriage by using individual patient data from efficacy trials. Detailed information on each patient enrolled in these trials was obtained to evaluate the efficacy of IVIG and investigate the effect of clinical variability on pregnancy outcome. Data from 125 patients in the IVIG group and 115 patients in the placebo group were available for analysis. Although the number of previous miscarriages and female age were both negative prognostic factors for successful outcome, there was no significant improvement in successful pregnancy or live birth rate with IVIG. Subgroup analyses indicated that timing of IVIG administration may be important. The results of the present study highlight the importance of stratification for known confounders, so that the role of IVIG can be evaluated in more detail. The collective evidence thus far indicates that IVIG does not have a therapeutic effect that is clinically meaningful.

Efficacy of a two-component acellular pertussis vaccine in infants

OBJECTIVE

This case-control study investigated the protective efficacy against pertussis of three doses of a two-component acellular pertussis vaccine (manufactured by Biken in Japan) combined with diphtheria and tetanus toxoids (manufactured by Connaught Laboratories in the US) in infants.

METHODS

A case-control study was performed in 63 pediatric practices in Germany. Prospective recruitment of 16,780 infants ages 6 to 17 weeks took place between February, 1993, and July, 1994. According to parental choice infants received either Biken acellular pertussis vaccine combined with diphtheria and tetanus toxoids (DTacP) (74.6%) at approximately 2, 4 and 6 months of age, or a licensed German diphtheria-tetanus toxoids-whole cell pertussis vaccine (10.9%), diphtheria-tetanus toxoids vaccine (12.5%) or no vaccine (2.0%). Prospective surveillance of pertussis cases between February, 1993, and May, 1995, was accomplished by culturing all infants < or =2 years of age presenting with cough > or = 7 days. A pertussis case was defined as any cough of 21 days or longer plus a positive Bordetella pertussis culture or household contact exposure.

RESULTS

We identified 241 pertussis cases prospectively by 11,017 B. pertussis cultures and 949 controls matched for age were selected from the same pediatric practices. Medical history and demographic and vaccine status data were collected from each case and for four controls. Data were analyzed through conditional logistic regression taking into account individual matching and adjusting for potential confounding variables. DTacP combined with diphtheria and tetanus toxoids vaccine was 82% protective (95% confidence interval, 68 to 90), diphtheria-tetanus toxoids-whole cell pertussis vaccine was 96% protective (95% confidence interval, 78 to 99). Protection against typical B. pertussis infection characterized by paroxysmal cough lasting > or =21 days was 96% (95% confidence interval, 87 to 99) for DTacP and was 97% (95% confidence interval, 79 to 100) for diphtheria-tetanus toxoids-whole cell pertussis vaccine. Adjustment for potentially confounding variables did not change the results significantly.

CONCLUSIONS

Three doses of the two-component acellular pertussis vaccine protected infants against pertussis disease during the period before the recommended booster vaccination. For typical pertussis disease as defined by the WHO efficacy was high and similar to that of a licensed German diphtheria-tetanus toxoids-whole cell pertussis vaccine.

Pain in the newborn

This article reviews historic assumptions about newborns that have influenced the clinical management of pain in the newborn. These are discussed in light of more recent evidence that newborns not only experience pain but that their responses to pain may compromise their medical status and development. Currently available techniques for assessing newborn pain are considered with special emphasis on an objective clinical index of newborn pain.