bluuebunny/crossref_metadata_2025 huggingface dataset:
EFFECT OF MORBIDITIES ON COSTS OF END‐STAGE RENAL DISEASES (ESRD) PATIENTS IN THE TOP END OF THE NT
Authors: You Jiqiong
Published: July 2002

Objectives The continuing care cost of maintaining ESRD patients includes not only the cost of dialysis, but also the costs of treating comorbidities related to dialysis treatments (MRD) and not related to dialysis treatments. This study examined the relationship between comorbidities and costs. Methods: Cost information of ESRD patients was derived from Royal Darwin Hospital costing study in 1996/97 and 1997/98 financial years. Diagnosis Related Groups (DRGs) assigned to patients who were hospitalised were re‐categorised as 19 groups of comorbidites. Multiple linear regression (MLR) model was developed to analyse the relationship between diseases and costs. A forward selection strategy was applied to select diseases significantly affecting costs. Results: In that 2‐year period, 167 people (102 Aboriginals (A), and 65 non Aboriginals) were treated for ESRD, at a total cost of $12.7million. Provision of dialysis treatment alone cost $9.7m (76% of total cost). One hundred and thirteen people (85% of A, 40% of non A) had intercurrent hospitalisations for comorbidities at a cost of $3m (24%), with 530 episodes. Of these episodes, the most frequent reasons of admission for A were: water and electrolyte disorder (WED 25%), respiratory diseases (RD 20%), and surgical procedure (13%), while for non A, they were cardiovascular diseases (CVD 27%), WED (17%) and SP (15%) (see below). The following diseases (p < 0.05) were chosen in the final MLR model in terms of cost: SP, RD, CVD, WED, MRD, and access procedure etc. SP, RD and CVD accounted for 30%, 18%, and 11% of the $3m.

% of episodes
SP
RD
CVD
WED
MRD
Access

AB (% of 422)
13
20
12
25
5
0.9

non AB (% of 88)
15
7
27
17
5
5

Cost %
30
18
11
9
6
5

Conclusions

To reduce the continuing care costs for ESRD patients, greater efforts must be made to decrease the comorbidities. Prevention of surgical diseases, respiratory infection, and heart diseases might reduce the morbidity rate in ESRD patients, and subsequently reduce costs.
GLOMERULOSCLEROSIS IN INTERLEUKIN‐4 TRANSGENIC MICE HAS A NON‐IMMUNE ETIOLOGY
Authors: Rüger Bm , Erb Kj , He Y , Lane Jm , Davis Pf , Hasan Q
Published: July 2002

Background Mice with constitutive transgenic (tg) expression of interleukin‐4 (IL‐4) develop autoimmune‐type disorders resembling lupus nephritis. The kidneys show progressive glomerulosclerosis with immunoglobulin (Ig) and complement deposition.

Methods This study investigated the role of renal IL‐4 expression and the relevance of glomerular Ig deposition in the pathogenesis of glomerulosclerosis in IL‐4tg mice. The mice were treated with either IL‐4 neutralizing antibody or the glucocorticoid methylprednisolone (MP). To further clarify whether the renal lesions were exclusively immune‐mediated, IL‐4tg mice were cross‐bred with δ chain deficient mice (δ MT‐/‐), which are unable to produce Igs.

Results Glomeruli of anti‐IL‐4‐treated tg mice showed a normal structure with negligible Ig deposits. Similarly, in MP‐treated tg mice only trace amounts of glomerular Ig deposits could be detected, although in comparison with wt mice, increased mesangial collagen deposition was evident. Despite complete absence of renal Ig deposits, IL‐4tg/δMT‐/‐ mice developed progressive glomerulosclerosis with mesangial accumulation of collagen types I, IV and V. Renal IL‐4 expression was observed in both anti‐IL‐4‐ and MP‐treated IL‐4 tg mice, as well as in IL‐4tg/δMT‐/‐ mice. There was no statistically significant difference in the number of glomerular T cells and macrophages between the groups.

Conclusions Our data demonstrate that in this model glomerulosclerosis developed independently of and prior to Ig deposition, and imply that the initial accumulation of glomerular extracellular matrix was due to renal IL‐4 expression.
Factors associated with coverage of iodine deficiency disorders by control programs in an endemic area in West Sumatra, Indonesia
Authors: M Masrul  , V Chongsuvivatwong  , Af Geater
Published: July 2002

In order to ascertain the coverage and to identify factors determining the success of an iodine deficiency disorders (IDD) control program in West Sumatra, Indonesia, a cross‐sectional study among 495 school children aged 6–15 years in a subdistrict of an endemic goitre area was conducted. Coverage of iodine capsule distribution was 27%. Forty‐eight percent of the households used iodized salt with an appropriate concentration (≥ 40 p.p.m.). Factors associated with not taking idodine capsules among children were: mother’s lack of knowledge about the iodine capsule (OR 13.3, 95% CI 7.4–24.1) and mother’s education level (OR 1.89, 95% CI 1.05–3.39). For unsatisfactory use of iodized salt in a household, the only predictor was family monthly income. Odds ratios and 95% CI for moderate and high family income were 2.42 (1.39–4.21) and 2.22 (1.4–3.54), respectively. We concluded that for coverage in an IDD control program, supplementation and fortification alone were not enough. Education had an impact on coverage of the supplementation. Furthermore, iodization of salt needs further improvement in relation to quality control. Finally, the program neglected high‐income groups. These pitfalls should be corrected.
Gasless retroperitoneoscopic partial nephrectomy for a case with renal cell carcinoma
Authors: SAKAKIBARA NAOYUKI , SHINOJIMA HIROKAZU , MATUGASE YASUKUNI , MORITA KEN , HISAJIMA SADAKAZU
Published: July 2002

A 53‐year‐old man with incidental renal cell carcinoma underwent gasless retroperitoneoscopic partial nephrectomy. Convalescence was uneventful. There remained no evidence of disease during the 58‐month follow up.
Nutrition for Women in their Childbearing Years: A Review of the Literature and a Summary of Expert Recommendations
Authors: Suitor Carol West
Published: July 2002

In order to provide the best care to women and their future children, physicians and other clinicians should have a solid understanding of the women they treat as well as the most up‐to‐date information on preconceptional and prenatal nutrition practices. This paper, which consists of a demographic portrait of American women in their childbearing years in the United States, a comprehensive review of the recent scientific literature on preconceptional and prenatal nutrition, and a summary of expert recommendations, should provide clinically useful background in this regard. Topics covered include maternal weight gain, dietary recommendations, physical activity, strategies for preventing pre‐eclampsia, managing gestational diabetes mellitus, and multiple gestation.
POSTIRRADIATION LUMBOSACRAL RADICULOPLEXOPATHY: IMPROVEMENT AFTER IMMUNE THERAPY
Authors: Bersano A. , Carpo M. , Di Troia A. , Scarlato G. , Nobile‐Orazio E.
Published: July 2002

A delayed progressive impairment of peripheral nervous system including brachial and lumbosacral radiculoplexopathy is a well‐known complication of local radiotherapy. No treatment for this infrequent complication is currently available. Recently, improvement after treatment with high dose immunoglobulin (IVIg) has been reported in some patients, suggesting either an immune‐mediated inflammatory nerve damage induced by irradiation or a dysimmune neuropathy (CIDP‐like) misdiagnosed as a postirradiation disease. We report on two patients who developed motor lumbosacral radiculoplexopathy several years after local radiotherapy. The first patient (ZA) is a 49 y.o. man developing a progressive proximal>distal weakness and hypotrophy of lower limbs, 20 years after radiotherapy of lumbosacral region for seminoma. Electrophysiological studies showed markedly reduced motor conduction velocities (CV) and prolonged F‐wave latencies in lower limb nerves.

The second patient (BF), is a 52 y.o. woman who developed progressive left brachial plexopathy and distal>proximal weakness and hypotrophy of lower limbs 12 years after a first course of toracoascellar and lumbar irradiation for Hodgkin lymphoma followed by a second course of cervicoclavicular irradiation for tumor recurrence 7 years later. Electrophysiological studies showed markedly reduced CMAP amplitudes and proportionally reduced CV in motor nerves. No sensory impairment was detected in both patients. CSF protein was elevated in both patients while cells were normal. On the assumption of a possible dysimmune origin of the disease, patient ZA underwent high dose intravenous steroid treatment, while patient BF, who had previously deteriorated after steroids, was treated with IVIg. After treatment, patient ZA became able to walk with less waddling, to rise from the floor and climb stairs without support, and to run. Improvement was less consistent in patient BF, whose right leg strength improved even if she still needed bilateral support to walk. The improvement observed in both patients supports the hypothesis that, at least in some patients, an immune‐mediated mechanism may underlie postirradiation radiculoplexopathy.
QUANTITATIVE SENSORY TESTING AND SWEAT FUNCTION IN FRIEDREICH'S ATAXIA. CORRELATION WITH CUTANEOUS INNERVATION
Authors: Nolano M. , Provitera V. , Crisci C. , Saltalamacchia A. , Filla A. , Wendelshafer‐Crabb G. , Kennedy W.R. , Santoro L. , Caruso G.
Published: July 2002

To evaluate small fiber function in Friedreich's Ataxia (FA), we performed in 7 patients pin‐prick, thermal thresholds, and sweat test. All tests were performed in four different sites: hand dorsum, anterior thigh, lateral distal leg, and foot dorsum. The same subjects underwent 3 mm punch skin biopsy from fingertip, anterior thigh, and lateral distal leg. We used a thin needle mounted on a calibrated nylon wire for the pin‐prick test, and a Medoc 2001 TSA system for thermal threshold assessment. Sweat test was performed using a silicon mold after stimulation with pilocarpine by iontophoresis.

Skin specimens, cut into 100‐μm‐thick sections, were double‐stained using primary antibodies specific for collagen and nervous fibers and secondary antibodies labeled with Cy3 and Cy5 fluorophores. Tridimensional digitized images were obtained from z‐series of 2‐μm‐thick optical sections acquired with a confocal microscope.

We found in all patients in the more distal sites definite signs of functional impairment of the small fibers. These data correlated with the skin innervation morphological findings that showed, in the same sites, a sensible loss of small fibers regarding both the epidermal free endings and the subepidermal neural plexus. Less severe morphological abnormalities were found in the proximal sites.

The large fiber neuropathy in FA is well documented. Our data show a length‐dependent involvement of small fibers in the pathological process.
AN OPEN STUDY OF RILUZOLE VERSUS RILUZOLE PLUS GABAPENTIN IN AMYOTROPHIC LATERAL SCLEROSIS
Authors: Palma V , Brescia Morra V , Polverino M , Santoro L , Caruso G.
Published: July 2002

A randomised open study has been carried out to evaluate the efficacy of riluzole versus riluzole plus gabapentin in 50 patients (23 males, 27 females) affected by amyotrophic lateral sclerosis (ALS), who received the diagnosis according to El Escorial WFN criteria. At baseline, the mean age of the patients was 58.8 ± 11.7 years and the mean disease duration was 11.4 ± 5.9 months. Twenty patients had bulbar and 30 spinal onset. Twenty‐eight patients were randomly assigned to riluzole (100 mg/day) and 22 to riluzole plus gabapentin at the initial dose of 300 mg/day, slowly increased to 1800 mg/day. Informed consent was obtained in all cases. Before treatment, each patient underwent neurological examination, Appel rate scale, pulmonary function tests, electromyography, and transcranial magnetic stimulation. Clinical examination and electrophysiologic tests were repeated at three‐month intervals. Over the course of the trial, 4 patients (8%) were lost to follow‐up and 16 (32%, 9 in the riluzole and 7 in the riluzole plus gabapentin group) died. The mean age at death was 65.0 ± 6.5 years after a mean disease duration of 20.8 ± 7.9 months (range 13–36). There was no significant difference in response to treatment when severity and duration of the disease were compared in the two groups.
ATYPICAL DEMYELINATING CHARCOT‐MARIE‐TOOTH DISEASE AND MYELIN GENE MUTATIONS
Authors: Pareyson D. , Sghirlanzoni A. , Botti S. , Lauria G. , Ciano C. , Morbin M. , Taroni F.
Published: July 2002

Among our series of patients with inherited demyelinating neuropathies, we identified families showing atypical features and carrying mutations in myelin genes. We observed two sibships with Dejerine‐Sottas disease born to consanguineous parents both affected by a mild Charcot‐Marie‐Tooth neuropathy with only slight nerve conduction showing (>40 m/sec in upper limbs). The children carried a homozygous frameshift mutation in the P0 gene (Val102fs) resulting in a nonfunctional protein truncated very early in the extracellular domain. The parents, harboring the mutation in heterozygous form, had a distinct phenotype, milder than that observed in other reported cases of CMT1B, which can be misdiagnosed as the axonal form CMT2 and resembles the phenotype of the P0‐deficient heterozygous mice. In another family with autosomal dominant CMT1, there was a striking association with bilateral trigeminal neuralgia in several family members. Screening for gene mutations revealed a heterozygous missense mutation in the P0 gene. We fully evaluated a family in which a 66‐year‐old man and his 32‐year‐old daughter had a severe early‐onset demyelinating neuropathy. The father, chairbound since age 55, also had cranial nerve involvement (oculomotor paresis with diplopia, sensorineural hearing loss, and vocal cord paresis requiring tracheostomy). Sural nerve biopsy in the daughter demonstrated severe loss of myelinated fibers with several complex onion bulb formations. Both patients carried a heterozygous missense mutation (Arg381His) in the gene coding for Early Growth Response 2 (EGR2), a Schwann cell transcription factor that is thought to regulate myelinogenesis and cranial nerve development.

Supported by Telethon grants to A.S. and F.T.
MYELINATION DEFICIT IN NERVE OF SUCKLING RATS DUE TO CYCLOLEUCINE ‐INDUCED DEFICIENCY OF METHYL DONORS
Authors: Bianchi R. , Baiguera L. , Di stasi D.  , Tacconi M.T.
Published: July 2002

We used cycloleucine (CL) — which prevents methionine conversion to S‐adenosyl‐methionine (SAMe) by inhibiting ATP‐L‐methionine‐adenosyl‐transferase (MAT) — to characterize the lipid and protein changes induced by methyl donors deficit in peripheral nerve and brain myelin in rats during development. We have previously shown that CL (400 mg/kg ip) given to suckling rats at days 7, 8, 12, and 13 after birth reduced brain and sciatic nerve weight gain, brain myelin content, protein, phospholipid (PL), and galactolipid concentration in comparison to control. Among PLs, only sphingomyelin (SPH) significantly increased by 35–50%. SAMe p‐toluensulphonate (SAMe‐SD4) (100 mg/kg, ip) given daily from day 7, as with exogenous SAMe, partially prevented some lipid alterations induced by CL, particularly galactolipid and SPH. To test the ability of CL to affect PL metabolism we have measured de novo PL biosynthesis, ex vivo in nerve homogenates (in comparison with brain homogenates) from control and CL‐treated animals killed at day 18 after birth, starting from labelled substrates ([3H]‐choline, specific activity 20 mCi/mmol) in a Tris/HCl buffer, containing 5 mM MgCl2, 0.2 mM EDTA, 0.1 mM ATP, and 0.5 mM of the labelled substrates. After 60 min incubation, lipids were extracted, PL separated by TLC, and corresponding silica gel fractions scraped and counted in a liquid scintillator. Phosphatidylcholine enrichment in labelled choline resulted in slight increases in brain and sciatic nerve of CL‐treated rats, suggesting an increased synthesis rate via the Kennedy pathway, possibly due to the reduced availability of methyl donors. Interestingly, choline incorporation into SPH in brain and nerve myelin resulted in significant increases of 30–40%. In agreement with the observed decrease of galactolipid content and the relative increase in SPH, these data suggest an alteration in sphingolipid metabolism after CL.

Among proteins, in sciatic nerves of CL‐treated pups the relative content of a number of polypeptides, namely the 116, 90, 66, 58, and 56 kDa bands, decreased, whereas others increased; the most abundant PNS protein, protein zero, remained unchanged. The analyses of myelin basic protein isoforms revealed a dramatic increase in the 14.0 and 18.5 forms, indicating early active myelination. SAMe‐SD4 treatment counteracted, and in some cases normalized, these changes.

In summary, methyl donor deficiency induced by MAT inhibition produces myelin lipid and protein alterations, partly counteracted by SAMe‐SD4 administration.

The financial support of Telethon‐Italy (grant No. D 51) is gratefully acknowledged.
A NOVEL MUTATION OF CONNEXIN‐32 GENE IN A CMTX ITALIAN FAMILY
Authors: Siciliano G. , D'avino C. , Pellegrinetti A. , Rocchi A. , Sartucci F. , Mostacciolo M.L.
Published: July 2002

X‐linked Charcot‐Marie‐Tooth is an inherited motor and sensory neuropathy associated with mutations in GJB1, a gene on chromosome X coding for the gap junction protein “connexin 32” (Cx32). Cx 32 gene is expressed in both peripheral and central nervous system myelin.

We describe a family affected by X‐linked CMT neuropathy with a novel point mutation in Cx32 gene, in which the mother, the putative carrier, and three affected sons were examined. The affected sons (32, 35, 38 yrs) presented a motor‐sensory slowly progressive neuropathy mainly involving lower limbs. Nerve conduction study showed both axonal and demyelinating pattern of denervation. Evoked potentials indicated visual and brainstem auditory pathway involvement. The mother showed subclinical electrophysiological abnormalities in nerve conduction velocities.

By mutational analysis of GJB1 using SSCP and sequencing of candidate regions, a previously undescribed missense mutation in the exon 2, codon 151, was found. This mutation was due to a transversion (TAT‐> TCT) leading to a Tyr‐>Ser substitution in the 2nd extracellular domain.

Our findings further stress the wide variability in the spectrum of Cx32 mutations associated to CMTX, making it worthwhile to deepen knowledge about genotypic–phenotypic interrelationship in this disease.
COMBINED DEFICIENCY OF PYRUVATE DEHYDROGENASE AND MITOCHONDRIAL RESPIRATOR CHAIN COMPLEX I: CASE REPORT
Authors: Lori S. , Donati M.A. , Gasperini S. , Bardini M.R. , Nistri R. , Poggi G. , Garavaglia B. , Zammarchi E.
Published: July 2002

We described a male child of two years and three months affected by assial hypotonia, psicomotor retardation, muscular distal hypotrophy with hyporeflexia, dystonic movements and deafness. He was born from non‐consanguineous parents by spontaneous caesarian twin delivery at 38 weeks. His sister is healthy. He came to our observation at 16 months of age. Screenings for metabolic diseases and CSF neurotransmitters and lactate were normal, whereas the serum lactate was mildly increased. Brain MRI showed delayed myelination, with the normal lactate at the spectroscopic study. EEG showed interemispheric asymmetry with epileptic discharges. EMG showed a neurogenic pattern. Molecular DNA analysis for Spinal Muscular Atrophy was negative. Muscle biopsy showed neurogenic injury and an absence of ragged red fibers; enzymatic assay showed a severe deficiency of Complex I (2.8 nmol/min/mg protein, n.v. 17–33) and a mild deficiency of Pyruvate Dehydrogenase (PDHC=0.47 nmol/min/mg protein, n.v.0.8‐2).

The clinical features of patients with a dysfunction in mitochondrial metabolic pathways are variable. A PDHC deficiency leads to a graduated spectrum of neurological involvement starting from severe forms with death in the neonatal period, Leigh disease and carbohydrate‐induced episodic ataxia. The most common features associated with a PDHC defect are delayed development and hypotonia. Patients with Complex I deficiency show a variable phenotype from fatal infantile encephalomyopathy to adult‐onset myopathy; neurodegenerative disorders are also described: Parkinson's disease, dystonia and Leber's optic neuropathy. A combined PHDC and Complex I deficiency is rarely reported. We can make the hypothesis that a defect of a single enzyme (Complex I) can play a role on the other enzyme deficiency. The presence of a primitive PHDC and Complex I deficiency is unlikely be hypothesized since the parents are not consanguineous and a double genetic defect is improbable.
AUTOIMMUNE RESPONSES TO GLYCOLIPIDS IN PARANEOPLASTIC NEUROPATHY: REPORT OF TWO CASES
Authors: Bonetti B. , De Toni L. , Battistini L. , Borsellino G. , Alberti D. , Rizzuto N. , Nardelli E.
Published: July 2002

Glycolipids (GL) have been implicated as potential antigens in autoimmune neuropathies, but their role in paraneoplastic neuropathy has been poorly investigated. We describe two patients affected by lung neoplasia and subacute sensori‐motor axonal neuropathy with high titres of IgG auto‐antibodies against GM1, GD1b, GQ1b, GD1a, GD2, GM2, GM3, GD3, asialo‐GM1 and sulfatide. The first patient showed prevalent sensory axonal neuropathy, ophthalmoplegia and dysphagia. Small cell lung carcinoma was bioptically discovered and treated with chemotherapy and irradiation, which yielded clinical stabilization and decline of anti‐GL IgG titre in a two years follow‐up. The second patient complained of subacute, progressive distal hypostenia. Neurologic examination showed areflexic, hypotonic tetraparesis with marked wasting, fasciculations, mimicking lower motor neuron disease. In addition to anti‐GL IgG, we detected expansion of peripheral γ/δ T lymphocytes (3% of total T cells, n.v. <0.5%), a T cell subset known to recognize lipid antigens. Lung adenocarcinoma was discovered and surgically removed. After two months, neuropathy stabilized and both anti‐GL IgG and γ/δ T lymphocytes markedly declined. Immunohistochemistry on this patients' tumor showed expression of GM1, GD1a, GD2, GM2, GM3, GD3 on neoplastic cells, which were infiltrated by IgG and CD8 and γ/δ T lymphocytes. The association of neoplasia, peripheral neuropathy and autoimmune responses to GL observed in our patients proposes a previously underestimated role for GL as putative antigens in paraneoplastic neuropathy. GL should be considered as candidate antigens in paraneoplastic neuropathy and anti‐GL IgG should be evaluated in patients with subacute sensory and/or motor neuropathy.
Effects of Water and Nitrogen Supply on Water Use Efficiency and Carbon Isotope Discrimination in Edible Canna (Canna edulis Ker‐Gawler)
Authors: Brück H. , Jureit C. , Hermann M. , Schulz A. , Sattelmacher B.
Published: July 2002

Abstract: Transpirational water use efficiency (WUE) is affected by nutrient and water supply, but relatively little is known about the response of Andean root and tuber crops, such as edible canna (Canna edulis Ker‐Gawler). Two Canna edulis genotypes were studied in semi‐controlled greenhouse experiments at the International Potato Centre (CIP) near Quito, Ecuador. Under conditions of low water supply, shoot dry matter (DM), leaf area and specific leaf nitrogen (SLN) all decreased, while WUE was higher and carbon isotope discrimination (Δ) decreased. The large water‐storing hypodermal cells characteristic of this plant's leaf morphology shrank, concertina‐like, the leaves became thinner, and the specific leaf area increased significantly (from 26 m‐2 kg‐1 to 43 m‐2 kg‐1). In a second experiment, plants were grown with three different levels of nitrogen supply: from low to high N supply, shoot DM increased significantly (from 16 to 37 g), along with leaf area and SLN. At the lowest level of nitrogen supply (N0), WUE was significantly lower and Δ increased. As expected, the linear correlation between Δ and WUE was negative, but variation in Δ could only explain 49 % of the variation in WUE. If, in addition to Δ, measured root fraction (RF) and estimated values of leaf‐to‐air vapour pressure deficit (Δe) and respiratory and unproductive carbon loss were used to calculate WUE, the correlation between measured and calculated WUE was substantially improved, except for the water stress treatment. It is considered that, for root and tuber crops, RF and Δe are the major variables when Δ of single leaves is to be used for up‐scaling to plant WUE.
Measurement of GaAs/InP and InAs/InP heterojunction band offsets by x-ray photoemission spectroscopy
Authors: Waldrop J. R. , Grant R. W. , Kraut E. A.
Published: July 2002

The unstrained valence-band offset ΔEv for the x=0 and x=1 end points of the InxGa1−xAs/InP (100) heterojunction system has been measured by x-ray photoemission spectroscopy (XPS). Although the GaAs/InP and InAs/InP interfaces are strained because of lattice mismatch, the ΔEv values obtained by the XPS measurement method used are characteristic of an unstrained interface. Values of ΔEv (GaAs/InP)=0.19 eV and ΔEv (InAs/InP)=0.31 eV are observed. A linear interpolation between the x=0 and x=1 values gives ΔEv (In0.53 Ga0.47As/ InP)=0.25 eV for the x=0.53 lattice-matched interface (ΔEc /ΔEv =58/42).
Optimization and fabrication of grating beamsplitters in silicon nitride
Authors: Taghizadeh M. R. , Wilson J. I. B. , Turunen J. , Vasara A. , Westerholm J.
Published: July 2002

We report for the first time the generation of optimized space-invariant fan-out elements, so-called Dammann gratings [H. Dammann and K. Görtler, Opt. Commun. 3, 312 (1971)] in plasma silicon nitride. Diffraction efficiencies as high as 65% have been achieved. Using simulated annealing and the greedy algorithm, grating structures with fan-out as large as 201×201 can readily be calculated. Low absorption and high optical quality together with its ease of structuring make silicon nitride an ideal medium for the construction of phase-only optical elements.
Theory for the etching of organic materials by ultraviolet laser pulses
Authors: Sauerbrey R. , Pettit G. H.
Published: July 2002

A theoretical description of the ultraviolet laser etching process is developed. The threshold for laser ablation is reached when the density of absorbed photons is approximately equal to the density of chromophores in the material. Saturation of the absorption coefficient, absorption by the plume of ablated products, and multiphoton effects are considered. Agreement with all available experimental etch data, including femtosecond ultraviolet laser ablation, is found. The description is based on an analysis of the radiation transport at high intensities and is independent of the question as to whether ultraviolet laser ablation is photochemical or thermal.
Improved atomic force microscope images using microcantilevers with sharp tips
Authors: Akamine S. , Barrett R. C. , Quate C. F.
Published: July 2002

Novel force-sensing microcantilevers with sharp tips have been used to obtain atomic force microscope images of atomically flat, layered compounds as well as microfabricated samples with large-scale topographies. When imaging atomically flat samples using cantilevers with sharp protruding tips, atomic corrugations are observed more consistently and with a higher signal-to-noise ratio than in the absence of tips. Some asymmetric distortions arise when tipped cantilevers are used with forces larger than 10−7 N. Side by side comparisons of images of rough samples obtained using cantilevers with and without tips reveal that the presence of a sharp tip yields superior image quality of vertical features and trenches. The cantilever assembly is a microfabricated, silicon nitride cantilever with an integral, single-crystal silicon tip. The silicon tip is self-aligned to the end of the cantilever and is created by a process which simultaneously fabricates and sharpens the silicon tip. Initial transmission electron microscopy studies show that the single-crystal silicon tips have radii of curvature of 220–400 Å.
Thermal quenching of the photoluminescence of InGaAs/GaAs and InGaAs/AlGaAs strained-layer quantum wells
Authors: Lambkin J. D. , Dunstan D. J. , Homewood K. P. , Howard L. K. , Emeny M. T.
Published: July 2002

Photoluminescence in InGaAs/GaAs strained-layer quantum wells is strongly quenched by temperatures above 10–100 K, depending on the well width. Analysis of this dependence shows that the quenching mechanism is thermal activation of electron-hole pairs from the wells into the GaAs barriers, followed by nonradiative recombination through a loss mechanism in bulk GaAs. The addition of Al to the barriers to improve confinement eliminates loss through this route but introduces another loss mechanism, characterized by an activation energy independent of well width and with a smaller pre-exponential factor.
Barrier parameter variation in Al-Al2O3-metal tunnel junctions
Authors: Shu Q. Q. , Ma W. G.
Published: July 2002

A trapezoidal potential barrier was used to model an Al2O3 barrier layer in three different tunnel junctions: Al-Al2O3-Au, -Ag and -Cu. The trapezoidal tunneling barrier parameters were determined by fitting the calculated I-V curves to the experimental curves at 77 K. It is found that the barrier width of the Au-, Ag-, and Cu-junction is 24, 25, and 12 Å, respectively, and that the barrier heights of the three different junctions are close to each other at the Al-Al2O3 interface, but they are 1.05, 0.85, and 3.10 eV at the Al2O3-Au, -Ag, and -Cu interface, respectively. The Auger depth profiles of the junctions suggest that the variation of the barrier parameters with the top electrode may be due to diffusion of the top electrode atoms into the barrier and the occurrence of the oxidation reaction between the Al2O3 and the top metal electrode atoms in the region of the interfaces.
Thermally stable ZnO films deposited on GaAs substrates with a SiO2 thin buffer layer
Authors: Kim Hong Koo , Mathur Michelle
Published: July 2002

SiO2 thin films (1000-Å thick) were sputter deposited on GaAs substrates as a buffer layer in order to alleviate a thermal mismatching problem between ZnO films and GaAs substrates. Thermal stability of sputter-deposited ZnO films (0.5–2.0 μm thick) was tested on such a buffered GaAs substrate with a postdeposition heat treatment at 430 °C for 10 min, which is similar to a standard ohmic contact alloying condition. The films sustained the heat treatment well, not showing any crumbling, which has usually been a problem when a ZnO film is deposited directly on a GaAs substrate. The postdeposition anneal treatment also dramatically enhances c-axis orientation of the ZnO films and relieves intrinsic stress almost completely. These improvements are attributed to a reduction of grain boundaries and voids with the anneal treatment as supported by the scanning electron microscopy and x-ray diffraction measurement results.
Light emitting nanocrystalline silicon prepared by dry processing: The effect of crystallite size
Authors: Rückschloss M. , Landkammer B. , Vepřek S.
Published: July 2002

A new technique for the preparation of light emitting nanocrystalline (nc) silicon by a combination of plasma chemical vapor deposition and post-treatment consisting of oxidation and annealing in forming gas is reported. The advantage of this processing consists in the possibility of a control of the crystallite size and the fraction of nc-Si in the film. A strong increase of the photoluminescence below 35 Å, as predicted by theory, is documented experimentally.
Narrowband mid-infrared generation using KTiOAsO4
Authors: Kung A. H.
Published: July 2002

Continuously tunable mid-infrared radiation from 3.0 to 5.3 μm was produced by difference frequency mixing in KTiOAsO4. A photon efficiency of 7% for conversion to 4.4 μm was achieved, providing peak power exceeding 250 kW, and pulse energy of over 0.5 mJ in a 2 nanosecond pulse. An absorption spectrum of CO2 in air with better than 1 cm−1 resolution was obtained simply by scanning the wavelength of one of the input lasers.
Nitrogen stabilized 〈100〉 texture in chemical vapor deposited diamond films
Authors: Locher R. , Wild C. , Herres N. , Behr D. , Koidl P.
Published: July 2002

We have studied the influence of nitrogen impurities in CH4/H2 gas mixtures on the structure and morphology of polycrystalline diamond films prepared by microwave plasma assisted chemical vapor deposition. The nitrogen concentration in the process gas was varied between 1 and 1000 ppm. Optical emission spectroscopy was applied to detect the nitrogen in the plasma via emission from CN radicals. The morphology and texture of polycrystalline films prepared with various N2 impurity levels and CH4 concentrations in the range 0.5%–2% was investigated using scanning electron microscopy and x-ray texture analysis. For the films prepared with low methane concentrations (e.g., 0.5%) only a minor influence of the nitrogen was observed. However, most interestingly, for higher methane concentrations (1%–2%) the addition of small amounts of nitrogen turned out to have a tremendously beneficial effect on the film morphology and structure. Films prepared without additional nitrogen are of nanocrystalline structure and of minor quality, whereas films prepared with nitrogen concentrations in the range 10–100 ppm exhibit a pronounced 〈100〉 texture and a considerably improved crystalline quality as judged by Raman spectroscopy.
Chemical downstream etching of silicon–nitride and polycrystalline silicon using CF4/O2/N2: Surface chemical effects of O2 and N2 additives
Authors: Beulens J. J. , Kastenmeier B. E. E. , Matsuo P. J. , Oehrlein G. S.
Published: July 2002

By comparing the etching characteristics of silicon and silicon nitride in CF4/O2/N2 microwave downstream plasmas we demonstrate clearly how low concentrations of energetic species can play a dominant role in remote plasma processing: Injection of 5% N2 to a CF4/O2 plasma increases the silicon nitride etch rate by a factor of 7, while not significantly affecting the bulk composition of the discharge. Downstream injection of N2 is ineffective. Using surface spectroscopies we directly show a dramatic enhancement of the reactivity of fluorine and oxygen atoms with silicon and silicon–nitride surfaces upon N2 injection to the discharge. Our results can be explained by the production of energetic metastable species in the discharge region which transport energy to the gas-surface interface.
Effect of high pretilt angle for anchoring strength in nematic liquid crystal on rubbed polyimide surface containing trifluoromethyl moieties
Authors: Seo Dae-Shik , Kobayashi Shunsuke
Published: July 2002

The effects of high pretilt angle are investigated on the polar anchoring energy of the nematic liquid crystal (NLC), 5CB, on rubbed polyimide (PI) films containing trifluoromethyl moieties. The pretilt angle of 5CB rapidly increases up to about 45° with the rubbing strength (RS). Also, the polar anchoring energy of 5CB initially increases with the RS for weak rubbing and then decreases. From these results, we determined the relationship between the pretilt angle and the anchoring energy on rubbed PI films. We suggest that the polar anchoring energy of 5CB with a high pretilt angle is very small because of the combination of the microsurface excluded volume effect and the van der Waals interaction between the LC molecules and the substrate surface on weakly rubbed PI films containing trifluoromethyl moeities.
Frictional heat-stimulated exo-electron emission from alumina sliding surfaces
Authors: Ohuchi H. , Enomoto Y.
Published: July 2002

A new method has been developed to measure exo-electron emissions stimulated by frictional heating for a ball-on-disk sliding where a tungsten carbide was biased at +15 V dc to collect exo-electrons emitted from a γ-irradiated hot-pressed alumina disk. Exo-electron emission’s signals were detected above a certain critical velocity when the contact surface was frictionally heated to a critical temperature of 250 °C and emitted exo-electrons. Sliding temperatures at any conditions of load and velocity were thus estimated using the temperature calculation program M. F. Ashby, J. Abulawi, and H. S. Kong [T-MAPS Background Reading and User Manual, Cambridge University Engineering Department (Cambridge University, London, 1992); Tribology Trans. 34, 577 (1991)]. This method provides a versatile method of measuring the sliding temperature of ceramics.
Steady state pulsed laser deposition target scanning for improved plume stability and reduced particle density
Authors: Doughty C. , Findikoglu A.T. , Venkatesan T.
Published: July 2002

A pulsed laser deposition (PLD) oscillating target scanning technique, in which the laser ablates the target from opposing directions as the deposition proceeds, is described and compared to the conventional technique of target rotation over a cumulative ablation exposure of ∼1500 shots/site. Using conventional rotation the plume direction is eventually displaced by 6° while both the number density and size of PLD associated particles increase. In contrast, the oscillating technique results in a spatially stable plume (displacement <2°) while the particle density and size both decrease. This technique allows one to operate in a steady state mode without routine target maintenance, improves plume ‘‘walk off,’’ and deposition reproducibility while decreasing the production of particles.
Design of InGaAs linear graded buffer structures
Authors: Sacedón A. , González-Sanz F. , Calleja E. , Muñoz E. , Molina S. I. , Pacheco F. J. , Araújo D. , García R. , Lourenço M. , Yang Z. , Kidd P. , Dunstan D.
Published: July 2002

The relaxation of compositionally graded InGaAs buffers, with and without uniform cap layers, has been studied. Simple InGaAs linear-graded layers on GaAs substrates never reach complete relaxation. The residual strain in these structures produces a dislocation-free strained top region while the rest of the buffer is nearly completely relaxed through misfit dislocations, as observed by transmission electron microscopy (TEM). This strained top region is analyzed and its thickness compared with theoretical calculations. The effects of different cap layers on the relaxation behavior of the graded buffer has been studied by double crystal x-ray diffraction, TEM, and low temperature photoluminescence, and results compared with predictions of the models. The optical quality of the cap layer improves when its composition is close to the value that matches the lattice parameter of the strained surface of the grade. The design of linear graded buffers having a strain-free cap layer with high crystalline quality is discussed.
Low-temperature heat switch using unforced convection
Authors: Torii Rodney H. , Maris Humphrey J.
Published: July 2002

A new type of low-temperature heat switch is described. The switch uses unforced convection of helium gas within a closed loop. We report measurements of the performance of a simple version of the heat switch.
Modeling the ion-source performance of an electron-beam ion trap (invited)
Authors: Penetrante B. M. , Schneider D. , Marrs R. E. , Bardsley J. N.
Published: July 2002

Several key features of the electron-beam ion trap (EBIT) enable it to provide superior ion-source performance for many applications requiring ultra-high-charged ions. This paper briefly reviews these features and the operating conditions in the existing EBITs. The present performance of the EBIT as an ion source is demonstrated by producing and extracting ions up to Th80+ and U70+ at microsecond-wide ion beam pulses of about 104 ions per second. Using as examples the production of U92+, U90+, and Dy66+, modeling results are presented to show how the fundamental processes limit the quality and quantity of ions that can be obtained from an upscaled EBIT.
On the photodeflection method applied to low thermal diffusivity measurements
Authors: Bertolotti M. , Li Voti R. , Liakhou G. , Sibilia C.
Published: July 2002

The photodeflection method when applied to measure the low thermal diffusivity of some materials gives inconsistent results. In this article a way to extend the thermal diffusivity range of measurements using the phase of the photodeflection signal is presented. A comparison with computer simulations and experimental results shows good agreement.
Low energy x-ray spectrometer for an electron beam ion trap
Authors: Beiersdorfer P. , Wargelin B. J.
Published: July 2002

A flat-crystal spectrometer for analyzing ultrasoft x rays in the wavelength region 10–25 Å was constructed for use on an electron beam ion trap. The spectrometer employs a position-sensitive proportional counter for detection and affords a nominal resolving power of 2000 at a Bragg angle of 45°. Measurements of the L-shell spectra of Ne-like Fe16+ and of the 3s1/2–3p3/2 transitions in near Na-like Pb71+, which fall into the wavelength region from 13.5 to 17.5 Å, are presented demonstrating high throughput and excellent signal-to-noise characteristics. The actual resolving power achieved was limited by the intrinsic resolution of the crystal to 500. A resolving power close to the nominal value was achieved in second order Bragg reflection.
Multicusp ion sources (invited)
Authors: Leung K. N.
Published: July 2002

During the last decade, different types of multicusp ion sources, such as high current, high concentration H+, H+2, or N+ ion sources, negative ion sources, radio-frequency-driven sources, and high charge state ion sources have been developed at the Lawrence Berkeley Laboratory. This article reviews the history of the research and development of these ion sources and their applications.
Multichannel SQUID system detecting tangential components of the cardiac magnetic field
Authors: Tsukada Keiji , Haruta Yasuhiro , Adachi Akira , Ogata Hisanao , Komuro Takanori , Ito Tsuyoshi , Takada Youichi , Kandori Akihiko , Noda Yasunaga , Terada Yasushi , Mitsui Toshio
Published: July 2002

The 32-channel SQUID system described here is used for diagnosing heart disease by measuring the x and y components of the cardiac magnetic field. To detect a magnetic field parallel to the body surface, it uses a compact hybrid superconducting quantum interference device (SQUID) gradiometer consisting of a planar pickup coil (fabricated using thin-film techniques) and a square double-washer dc-SQUID having large voltage-flux transfer function. The SQUIDs are operated in a flux-locked mode using simple readout circuits connected directly to the preamplifier without additional positive feedback. The system is installed in a magnetically shielded room in a hospital. A low noise characteristics lower than 10 ft/√ Hz in a white noise is obtained in the hospital. Examples of tangential magnetocardiogram (MCG) measurements presented here show that the MCG obtained using this gradiometer makes it easy to visually estimate the electrophysiological behavior of the heart.
A modified high-temperature cell (up to 3300 K) for use with a cubic press
Authors: Bhaumik S. K. , Divakar C. , Mohan Murali , Singh A. K.
Published: July 2002

A high temperature-high pressure pyrophyllite cell with a graphite heater has limitations when temperature exceeds ∼2100 K. A conventional cell used with the cubic anvil high pressure apparatus has been modified to reach ∼3300 K. The heater power versus temperature calibration curve has been established using Pt–Pt10%Rh thermocouple up to 1900 K. For calibration above 1900 K, the heater powers required to initiate melting in Al2O3, Y2O3, and TiB2, and decomposition of α-SiC have been determined. The melting (or decomposition) of the specimens has been detected by examining the microstructure of the specimens recovered after pressure-temperature treatment.
A diamond double-crystal transmission monochromator for the TROIKA II station at ESRF
Authors: Grübel G. , Abernathy D. , Vignaud G. , Sanchez del Rio M. , Freund A.
Published: July 2002

The performance of a diamond double-crystal monochromator for the TROIKA II station at the ESRF was studied. Two (111) oriented diamond crystals for Bragg geometry (120 mm and 500 mm thick) were combined in a nondispersive horizontal scattering geometry and characterized in the white Troika undulator beam. The observed rocking curves were slightly broadened due to nonuniform defect distributions present in the crystals. No heat-load-induced broadening was found. The measured reflectivities compared well to the calculated values, and it was shown that a double-crystal Bragg monochromator can replace a single-reflection Laue monochromator without loss in flux.
Acoustical measurement of the trapping constant of porous materials
Authors: Debray Alexis , Allard Jean F. , Lauriks Walter , Kelders Luc
Published: July 2002

A simple method of measuring the trapping constant of porous materials saturated by air is presented. The trapping constant is evaluated from acoustical measurements of the imaginary part of the compressibility of the saturating air at low frequencies. Measurements performed on random packings of spheres are compared with predictions obtained from numerical simulations. Conversely, the connection between the behavior of the compressibility and a well defined physical parameter provides new information about the efficiency of porous sound absorbing materials at low frequencies.
Development of a 130-mA, 75-kV high voltage column for high-intensity dc proton injectors
Authors: Sherman Joseph , Arvin Andrew , Hansborough Lash , Hodgkins Dave , Meyer Earl , Schneider J. David , Stevens R. R. , Thuot Michael , Zaugg Thomas
Published: July 2002

A reliable high-voltage (HV) column has been developed for dc proton injectors with applications to high-intensity cw linacs. The HV column is coupled with a microwave-driven plasma generator to produce a 75-keV, 110-mA dc proton beam. Typical proton fraction from this source is 85%–90%, requiring the HV column and accelerating electrodes to operate with a 130-mA hydrogen-ion beam current. A glow-discharge, which was caused by the ion source axial magnetic field, was initially observed in the HV column. This problem was solved by scaling the electron production processes, the magnetic field, and the HV column pressure into a favorable regime. A subsequent 168 h reliability run on the 75-keV injector showed that the ion source (plasma generator and HV column) has >98% beam availability.
Application to dielectric, metallic, and magnetic samples of a transmission mode scanning near field optical microscope with normal force distance regulation on bent optical fibers
Authors: David T. , Chicanne C. , Richard N. , Krenn J. R. , Scheurer F. , Ounadjela K. , Hehn M. , Lacroute Y. , Goudonnet J. P.
Published: July 2002

We have developed a scanning near field optical microscope (SNOM) based on bent optical fiber probes with a normal force atomic force microscopies (AFM) regulation. The optical fibers are used both as optical probes and AFM cantilevers. This SNOM was especially developed for transmission mode SNOM and it offers the possibility to realize simultaneously all AFM modes imaging and optical analysis. The fiber is used to illuminate the sample and the detection is performed through an inverted optical microscope. This article presents results obtained on dielectric, metallic, and magnetic samples with submicronic features. We have resolved the object of 80 nm in size, separated by 40 nm, and we illustrate the capabilities of our SNOM in investigating, locally, the variation of the optical properties of periodic samples, even though contaminant, and for a large variety of samples.