21 research outputs found

    Non-conserved dynamics of steps on vicinal surfaces during electromigration-induced step bunching

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    We report new results on the non-conserved dynamics of parallel steps on vicinal surfaces in the case of sublimation with electromigration and step-step interactions. The derived equations are valid in the quasistatic approximation and in the limit f1lDl±lif^{-1}\gg l_D\gg l_{\pm} \gg l_i, where ff is the inverse electromigration length, lDl_D the diffusion length, l±l_{\pm} the kinetic lengths and lil_i the terrace widths. The coupling between crystal sublimation and step-step interactions induces non-linear, non-conservative terms in the equations of motion. Depending on the initial conditions, this leads to interrupted coarsening, anticoarsening of step bunches or periodic switching between step trains of different numbers of bunches.Comment: 11 pages, 4 figures; revised and extended versio

    Adatom diffusion on vicinal surfaces with permeable steps

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    We study the behavior of single atoms on an infinite vicinal surface assuming certain degree of step permeability. Assuming complete lack of re-evaporation an ruling out nucleation the atoms will inevitably join kink sites at the steps but can do many attempts before that. Increasing the probability of step permeability or the kink spacing lead to increase of the number of steps crossed before incorporation of the atoms into kink sites. The asymmetry of the attachment-detachment kinetics (Ehrlich-Schwoebel effect) suppresses the step permeability and completely eliminates it in the extreme case of infinite Ehrlich-Schwoebel barrier. The average number of permeability events per atom scales with the average kink spacing. A negligibly small drift of the adatoms in a direction perpendicular to the steps leads to a significant asymmetry of the distribution of the permeability events the atoms thus visiting more distant steps in the direction of the drift.Comment: 12 pages, 6 figure

    Severe neurological outcomes after very early bilateral nephrectomies in patients with autosomal recessive polycystic kidney disease (ARPKD)

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    To test the association between bilateral nephrectomies in patients with autosomal recessive polycystic kidney disease (ARPKD) and long-term clinical outcome and to identify risk factors for severe outcomes, a dataset comprising 504 patients from the international registry study ARegPKD was analyzed for characteristics and complications of patients with very early (� 3 months; VEBNE) and early (4�15 months; EBNE) bilateral nephrectomies. Patients with very early dialysis (VED, onset � 3 months) without bilateral nephrectomies and patients with total kidney volumes (TKV) comparable to VEBNE infants served as additional control groups. We identified 19 children with VEBNE, 9 with EBNE, 12 with VED and 11 in the TKV control group. VEBNE patients suffered more frequently from severe neurological complications in comparison to all control patients. Very early bilateral nephrectomies and documentation of severe hypotensive episodes were independent risk factors for severe neurological complications. Bilateral nephrectomies within the first 3 months of life are associated with a risk of severe neurological complications later in life. Our data support a very cautious indication of very early bilateral nephrectomies in ARPKD, especially in patients with residual kidney function, and emphasize the importance of avoiding severe hypotensive episodes in this at-risk cohort. © 2020, The Author(s)

    Un cas inhabituel de duplication du canal rachidien.

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    We describe here a very rare congenital malformation, in which the vertebra Th 9 to 11 were divided into independent bodies and neural arches. The vertebral canal contained the spinal cord, whereas the space between bodies and arches was filled by nerve roots and a central remnant cord, not clearly connected to the main spinal cord. This malformation was considered as related to a fetal alcohol syndrome, with craniofacial and genitourinary abnormalities. The authors analyze, moreover the possible role of abnormal Sonic Hedgehog gene patterning in the pathogeny of this complex malformative sequence.Case ReportsEnglish AbstractJournal Articleinfo:eu-repo/semantics/publishe

    Initial screening for bedwetting : the use of questionnaires and voiding diaries : first results from a National Belgian study

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    Background: International guidelines advise that stratification of nocturnal enuresis (NE) into non-monosymptomatic (NMNE) and monosymptomatic (MNE) depending on the presence or absence of Lower Urinary Tract Symptoms (LUTS) respectively, is mandatory to optimize therapy. To identify LUTS a checklist (Clinical Management Tool (CMT)) and/or voiding diaries (home recordings) can be used. However, these recordings can be difficult for the family. Moreover, the added value of them, especially in treatment-naïve patients, is rather expert-opinion than evidence-based. Aim: document in treatment-naïve NE patients >5 years: 1) The prevalence of MNE vs NMNE 2) the added value and correlation of CMT and/or diary in differentiating NE. Design: visit 1: CMT was obtained, after a thorough history and basic assessments. If daytime incontinence (DI) and/or LUTS were identified, diagnosis was NMNE. Afterwards, a 2day voiding diary was registered at home. Visit 2: diary was evaluated; if LUTS or abnormal voiding frequency were present, diagnosis was NMNE. Results: 109 children included in 7 Belgian Hospitals (19 lost in follow-up); Mean age 7,7 (±2)years; 62 boys (68,9%), 27 girls (30%). Based on the CMT 13 children diagnosed as MNE (16,7%) and 75 as NMNE (83,3%). Based on the diary 16 children diagnosed as MNE (17,8%) and 74 as NMNE (82,2%). 25 children (27,8%) had the same diagnosis with both methods. Regarding the presence of LUTS we observed significant inconsistencies between the two modalities. There was fair agreement for urge (κ=0,219), moderate agreement for daytime incontinence (κ=0,432) and no agreement for abnormal voiding frequency (κ=-0,057). Conclusion: NMNE is more frequent than MNE in treatment-naïve patients. CMT alone versus CMT+diary had a different sensitivity and specificity of identifying LUTS : in absence of validation by a therapeutic trial, we state that we can only consider patients as MNE when both CMT and diary do not demonstrate LUTS

    Pitfalls of ketogenic diet in a neonate.

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    Case ReportsCommentLetterinfo:eu-repo/semantics/publishe
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