Experimental Study of Spectral Properties of a Frenkel-Kontorova System.

We report on microwave emission from linear parallel arrays of underdamped Josephson junctions, which are described by the Frenkel-Kontorova (FK) model. Electromagnetic radiation is detected from the arrays when biased on current singularities (steps) appearing at voltages V(n)=Φ(0)(nc̅/L), where Φ(0)=2.07×10(-15) Wb is the magnetic flux quantum, and c̅, L, and n are, respectively, the speed of light in the transmission line embedding the array, L its physical length, and n an integer. The radiation, detected at fundamental frequency c̅/2L when biased on different singularities, indicates shuttling of bunched 2π kinks (magnetic flux quanta). Resonance of flux-quanta motion with the small-amplitude oscillations induced in the arrays gives rise to fine structures in the radiation spectrum, which are interpreted on the basis of the FK model describing the resonance. The impact of our results on design and performances of new digital circuit families is discussed.

Prenatal genetic counseling referrals for advanced maternal age: still room for improvement.

OBJECTIVE: The objective of this study is to evaluate genetic risks already present before pregnancy in a cohort of pregnant women referred for prenatal genetic counseling exclusively for advanced maternal age (AMA). METHOD: We retrospectively reviewed the records of 1353 women referred over 1 year (2010) for pre-test genetic counseling with the only indication of AMA at three Italian Clinical Genetic Services. RESULTS: Of the 1353 women fulfilling the inclusion criteria of the study, 87 (6.4%) had cumulatively 94 genetic risk factors not previously identified (one risk factor in 80 patients and two risk factors in seven). Twenty-six risk factors (27.7%) concerned heterogeneous or multifactorial conditions and 68 (72.3%) Mendelian or chromosomal disorders and consanguinity.In nine out of these 87 women, the estimated risk for the offspring of a genetic disease or a significant structural anomaly was >5%. Additional testing according to the identified risks was performed in 36 of these 87 women/families. CONCLUSIONS: The proportion of cases with additional risk factors is smaller than reported in previous studies, but it remains substantial and confirms the need for strategies to increase awareness of the public and health professionals responsible for the care of women in childbearing age.

[The role of hypomagnesiuria in urolithiasis and renal colic: results from a prospective study of a metabolic evaluation protocola]. / Ruolo dell'ipomagnesuria nella colica renale da urolitiasi: risultati di uno studio prospettico sull'impiego di un protocollo di valutazione metabolica.

AIM: The stone disease of the urinary tract (urolithiasis) is a growing disease. The identification of metabolic disorders, treatable with prophylactic therapy, appears to be clinically important. The aim of this study was the analysis of metabolic disorders that promote and support the urolithiasis in a cohort of patients with renal colic at an Emergency Department. METHODS: In this prospective case series, we enrolled consecutive patients with renal colic treated at an Emergency Department within a Regional Teaching Hospital. We implemented a structured metabolic evaluation, which included blood chemistry studies, stone analysis and a 24-hour urine collection. We then evaluated the frequency of metabolic abnormalities alone or in combination. RESULTS: We enrolled 39 patients whit renal colic and a diagnosis of urolithiasis: 21 (54%) were males and the median age was 43.6 years (range 20-70). The most frequently observed type of stone was that of calcium oxalate (74%). Hypomagnesiuria was the most common metabolic abnormality found at the 24-hour urine collection (22/39, 56%), followed by hypocalciuria (31%), hypernatruria (20%), hyperuricuria (18%) and hyperoxaluria (15%). Among the associations of metabolic abnormalities, the hypocalciuria /hypomagnesuria was that observed with higher frequency (23%). CONCLUSION: We report an incidence of hypomagnesiuria (60%) in patients with renal colic higher than has ever been described in the literature. This result could be of importance in the knowledge of the pathogenesis of the urolithiasis and could have interesting implications in clinical practice.

Diamond layers grown by chemical vapor deposition on NbN systems and NbN/SiO2-based devices.

Deposits of individual diamond grains and continuous polycrystalline diamond layers have been generated by means of a HFCVD technique onto different types of untreated or seeded NbN surfaces. To test the feasibility of using diamond layers as protective coatings for aerospace applications, we carried out diamond deposition onto the lithographically defined NbN microelectrodes of a NbN/SiO2 multifinger device. The morphological and structural features of the diamond deposits and of the substrates were characterized by FE-SEM, XRD and Raman spectroscopy. The preferential growth of diamond on the superconductive NbN enables the selective coating of the NbN microstripes sputtered on the insulating SiO2. Moreover the diamond coating procedure is able to preserve the structural integrity of the substrate material and to retain the shaped architecture of the device. For the polycrystalline diamond layers grown on NbN a residual stress of -9.8 GPa, largely due to thermal stress, has been estimated by Raman analysis. The diamond coatings of the NbN-based architectures result to be mechanically stable.

Conditioning of Superconductive Properties in Graph-Shaped Reticles.

We report on phenomena observed in planar integrated networks obtained connecting superconducting island by Josephson tunnel junctions. These networks, identifiable as tree-like graphs, have branches consisting of series arrays of Josephson junctions which can be individually current biased and characterized. Both Josephson supercurrents and gap parameters of the arrays embedded in the graph structures display properties significantly different from those of "reference" arrays fabricated on the same chips and having identical geometrical shape. The temperature and magnetic field dependencies of the Josephson current of the embedded arrays both show a singular behavior when a critical value is reached by the Josephson characteristic energy. The gap parameter of the junctions generating the embedded arrays is higher than that of the junctions forming the reference geometrical arrays.

Hybrid carbon nanotube/nanodiamond structures as electron emitters for cold cathodes.

The field emission properties of hybrid carbon nanotubes/nanodiamond structures produced by one-step chemical vapor deposition (CVD) process have been investigated in order to assess their application as electron emitters for cold cathodes. The electron emission properties of a series of samples have been investigated by current-pressure, current-voltage and current-time measurements with the aim of testing the emission stability under working conditions relevant to technological applications. Stable emission, high values of current density and lack of arcing have been observed during prolonged working cycles, and without degradation of the material structure.

Quantitative measurement of indentation hardness and modulus of compliant materials by atomic force microscopy.

An atomic force microscopy (AFM) based technique is proposed for the characterization of both indentation modulus and hardness of compliant materials. A standard AFM tip is used as an indenter to record force versus indentation curves analogous to those obtained in standard indentation tests. In order to overcome the lack of information about the apex geometry, the proposed technique requires calibration using a set of reference samples whose mechanical properties have been previously characterized by means of an independent technique, such as standard indentation. Due to the selected reference samples, the technique has been demonstrated to allow reliable measurements of indentation modulus and hardness in the range of 0.3-4.0 GPa and 15-250 MPa, respectively.

Effects of anion-transport inhibitors on NaCl reabsorption in the rat superficial proximal convoluted tubule.

The effects of anion-transport inhibitors on volume reabsorption, and total CO(2) concentrations were examined by in vivo microperfusion of superficial proximal convoluted tubules of rats. The luminal perfusion solution was a high-chloride, low-bicarbonate solution like that in the in vivo late proximal tubule. The anion-transport inhibitors were only added to the luminal perfusion solutions. In tubules perfused with the control high-chloride solution, the rate of volume reabsorption (J(v)) was 2.3+/-0.2 nl/mm.min (n = 18), and the collected total CO(2) concentration was 4.0+/-0.3 mM. Furosemide (3 mM) caused a marked reduction in volume reabsorption to 0.8+/-0.3 nl/mm.min (n = 20) and only a slight increase in the total CO(2) concentration of collected samples of perfusate (7.8+/-0.5 mM). 0.8 mM acetazolamide caused a more pronounced rise in the collected total CO(2) concentrations to 10.7+/-0.5 mM but only a slight fall in J(v) to 1.7+/-0.3 nl/mm.min (n = 19). Hence, we inferred that inhibition of carbonic anhydrase only partially accounted for the inhibition of J(v) by furosemide. 4-acetamido-4'-iso-thiocyanato-stilbene-2,2'-disulphonic acid (0.1 mM), a well-characterized inhibitor of erythrocyte anion exchange mechanisms, also reduced J(v) to 1.6+/-0.3 nl/mm.min (n = 15) without changing the total CO(2) concentrations of the collected perfusates (3.6+/-0.4 mM). The effect of 4-acetamido-4'-iso-thiocyanato-stilbene-2,2'-disulphonic acid on volume reabsorption could not be explained by carbonic anhydrase inhibition because there was no increase in the total CO(2) concentration of the collected fluids. Furosemide did not significantly inhibit the rate of tracer glucose efflux out of the tubules, which suggests that the effect of furosemide on volume reabsorption was not a result of some nonspecific depression of active sodium transport. These results are discussed with respect to the possible effects of anion-transport inhibitors on the paracellular shunt pathway, active sodium reabsorption, and neutral sodium chloride transport.

Effect of carbonic anhydrase inhibition on superficial and deep nephron bicarbonate reabsorption in the rat.

The nephron segment responsible for the acetazolamide-insensitive fraction of renal bicarbonate reabsorption has not been clearly delineated. This study compares superficial and deep nephron bicarbonate reabsorption before and after acetazolamide at two dose levels (20 and 50 mg/kg per h) in mutant Munich-Wistar rats employing both cortical and papillary micropuncture and microcalorimetry. Systemic acid-base balance and right whole kidney glomerular filtration rate were similar in all groups examined. The effects of the two doses of acetazolamide were indistinguishable and resulted in a significant increase in whole kidney bicarbonate excretion that compared favorably with the fraction delivered out of the left papillary tip. Acetazolamide inhibited superficial proximal bicarbonate reabsorption by 80.0%, whereas reabsorption up to the deep loop of Henle was decreased by only 52% (P less than 0.001). Bicarbonate reabsorption that was insensitive to acetazolamide occurred in the superficial and deep loop of Henle and between the distal tubule and base collecting duct. Because water reabsorption in these segments could serve to generate transepithelial bicarbonate concentration gradients favorable for reabsorption, we attempted to minimize water abstraction by combined administration of mannitol and acetazolamide. During this condition a significant increase in bicarbonate delivery up to the deep loop of Henle was noted (52 vs. 65%), whereas superficial nephron reabsorption was not altered. Furthermore, an outwardly directed bicarbonate concentration gradient from the deep loop of Henle to vasa recta was demonstrated during acetazolamide (delta tCO2 = 20.9 +/- 3.3 mM), but was abolished during combined mannitol and acetazolamide administration (delta tCO2 = 3.5 +/- 0.9 mM). It is concluded that carbonic anhydrase inhibition results in a disparate effect on nephron bicarbonate reabsorption when juxtamedullary and superficial nephron segments are compared. Our findings suggest that a mechanism for residual bicarbonate reabsorption during acetazolamide administration may be passive reabsorption driven by favorable transepithelial concentration gradients.

Control of proximal bicarbonate reabsorption in normal and acidotic rats.

This free-flow micropuncture study examined the dependence of bicarbonate reabsorption in the rat superficial proximal convoluted tubule to changes in filtered bicarbonate load, and thereby the contribution of the proximal tubule to the whole kidney's response to such changes. The independent effects of extracellular fluid (ECF) volume expansion and of acidosis on proximal bicarbonate reabsorption were also examined. When the plasma volume contraction incurred by the micropuncture preparatory surgery was corrected by isoncotic plasma infusion ( congruent with1.3% body wt), single nephron glomerular filtration rate (SNGFR), and the filtered total CO(2) load increased by 50%. Absolute proximal reabsorption of total CO(2) (measured by microcalorimetry) increased by 30%, from 808+/-47 during volume contraction to 1,081+/-57 pmol/min.g kidney wt after plasma repletion, as fractional total CO(2) reabsorption decreased from 0.90 to 0.77. Aortic constriction in these plasma-repleted rats returned the filtered load and reabsorption of total CO(2) to the previous volume contracted levels. In other animals isohydric ECF expansion with plasma (5% body wt) or Ringer's solution (10% body wt), or both, produced no further diminution in fractional proximal total CO(2) reabsorption (0.76-0.81). Metabolic acidosis was associated with very high fractional proximal total CO(2) reabsorptive rates of 0.82 to 0.91 over a wide range of SNGFR and ECF volumes. At a single level of SNGFR, end-proximal total CO(2) concentration progressively decreased from 5.6+/-0.5 to 1.6 +/-0.2 mM as arterial pH fell from 7.4 to 7.1. Expansion of ECF volume in the acidotic rats did not inhibit the ability of the proximal tubule to lower end-proximal total CO(2) concentrations to minimal levels. In conclusion, bicarbonate reabsorption in the superficial proximal convoluted tubule is highly load-dependent (75-90%) in normal and acidotic rats. No inhibitory effect of ECF volume per se on proximal bicarbonate reabsorption, independent of altering the filtered bicarbonate load, could be discerned. Acidosis enabled the end-proximal luminal bicarbonate concentration to fall below normal values and reduced distal bicarbonate delivery.

Micropuncture determination of pH, PCO2, and total CO2 concentration in accessible structures of the rat renal cortex.

Previous studies evaluating the mechanism of renal HCO-3 reabsorption have assumed equilibrium between systemic arterial blood and tubular fluid PCO2. We have recently reported that the PCO2 in proximal and distal tubular fluid as well as the stellate vessel significantly exceeded arterial PCO2 by 25.9 +/- 0.92 mm Hg. The purpose of this study was to determine directly, for the first time, pH, PCO1, and total CO2 concentration in the accessible structures of the rat renal cortex with both microelectrodes and microcalorimetry. In addition, the concentrations of chloride and total CO2 were compared in the stellate vessel. The data demonstrate that: (a) values for total [CO2] in both the proximal tubule and stellate vessel calculated from in situ determination of pH and PCO2 closely agree with the measured values for total [CO2]: (b) values for chloride concentration in the stellate vessel are significantly less than the corresponding values in systemic plasma (delta[Cl-] = 5.6 meq/liter); and (c) the rise in [HCO-3] from systemic to stellate vessel plasma closely approximates the observed reciprocal fall in [Cl-] in this structure.

Reproductive behavior of thalassemic couples segregating for Cooley anemia.

The reproductive behavior in 1984 of families segregating for Cooley anemia in Ferrara was compared with that of a control group of families, matched for some biological variables which affect fertility. At the resolution power of the sample, it was found that there is no significant difference in these variables due to segregation for Cooley anemia, and it appears that there is no longer significant reproductive compensation in thalassemic couples, although a tendency to compensate does still exist. The increased life span of children affected by Cooley anemia, due to improvements in treatment in the past decade, is probably the main reason why the compensatory reproductive behaviour of the past has almost disappeared.

McCune-Albright syndrome: a longitudinal clinical study of 32 patients.

We report the diagnostic clinical features and their long term evolution in 32 patients with McCune-Albright syndrome. Patient data are made up of two periods: the first, classified as personal history, is from birth until the time when the diagnosis of McCune-Albright syndrome was made; the second, classified as clinical observation, is from the first observation until the end of follow up. The total duration of these two periods was 9.6+/-2.9 yr; mean age at first observation was 5.7 yr (range 0.7-11 yr). The probability of manifesting main clinical signs according to age was calculated: almost all had skin dysplasia at birth, 50% probability of peripheral precocious puberty in females at 4 years and 50% of bone dysplasia at 8 years of age were found. Other clinical signs had diagnostic relevance when preceding the main signs leading to diagnosis of McCune-Albright syndrome even without specific genetic investigation. The most important clinical manifestations have different evolutions: skin lesions increase in dimensions according to body growth; precocious puberty in females evolves rapidly but periods of regression can be seen in some patients; bone dysplasia in most patients evolves with an increase both in the number of affected bones and in the severity of lesions.

The Men's Adult Life Experiences Inventory: an instrument for assessing developmental concerns of middle age.

This article describes the development and testing of a new 97-item self-report instrument assessing the frequency and intensity of 11 developmentally related domains of concerns of middle-aged men. These include relationships (child, parents, wife, friends), job, health, sex, leisure, death, pressures of time, and self-reflection. The psychometric properties of the instrument, as well as potential uses, are discussed.

[The prevention of beta-thalassemia homozygosity]. / La prevenzione dell'omozigosi beta-talassemica.

Theoretical and practical aspects of programs for prevention of homozygous beta-thalassaemia are discussed and data concerning their efficacy are presented. Prevention of the beta-thalassaemia homozygous state is feasible at a reasonable cost.

[Effort hernia of the diaphragm: apropos of a case]. / Le ernie da sforzo del diaframma: a proposito di un caso.

The so-called stress diaphragmatic hernias are very unusual in the group of post-traumatic hernias. The Authors report a case and consider clinical, anatomical as well as pathophysiological aspects of the disease. Diagnostic procedures and therapeutic approach are also stressed.

Characterization of anomalous pair currents in Josephson junction networks.

Measurements performed on superconductive networks shaped in the form of planar graphs display anomalously large currents when specific branches are biased. The temperature dependences of these currents evidence that their origin is due to Cooper pair hopping through the Josephson junctions connecting the superconductive islands of the array. The experimental data are discussed in terms of theoretical models which predict, for the system under consideration, an inhomogeneous Cooper pair distribution on the superconductive islands of the network as a consequence of a Bose-Einstein condensation phenomenon.

Superconducting anisotropy in (CaCuO2)n/(SrTiO3)m superlattices.

The superconducting properties of (CaCuO2)n/(SrTiO3)m artificial superlattices have been investigated via transport measurements under the application of external magnetic fields. The coherence lengths in the plane of the substrate and in the direction perpendicular to it (ξab and ξc, respectively) have been measured while varying m, the thickness of the SrTiO3 block. The results show that with increasing m, i.e. with increasing structural anisotropy, the superconducting anisotropy γ = ξab/ξc decreases. This apparent anomalous relation between the structural and the superconducting anisotropies suggests that γ is more affected by local doping at the interface rather than by the separation between the superconducting blocks. This interpretation of the experimental results has been confirmed by both the irreversibility lines and the magnetic field dependence of the activation energy for fluxon motion.

Low temperature conductivity of carbon nanotube aggregates.

We compare, over wide temperature ranges, the transport properties of single-wall carbon nanotubes arranged in the form of aligned arrays or in the form of fibres. The experimental data show that both the forms of aggregates present a crossover in the transport mechanism from three-dimensional hopping of the electrons between localized states at high temperature to fluctuation-induced tunnelling across potential barriers at low temperature. The role of the junctions formed between the bundles in the array and between the nanotubes inside the fibres is discussed on the basis of the experimental results.

Indentation modulus and hardness of viscoelastic thin films by atomic force microscopy: A case study.

We propose a nanoindentation technique based on atomic force microscopy (AFM) that allows one to deduce both indentation modulus and hardness of viscoelastic materials from the force versus penetration depth dependence, obtained by recording the AFM cantilever deflection as a function of the sample vertical displacement when the tip is pressed against (loading phase) and then removed from (unloading phase) the surface of the sample. Reliable quantitative measurements of both indentation modulus and hardness of the investigated sample are obtained by calibrating the technique through a set of different polymeric samples, used as reference materials, whose mechanical properties have been previously determined by standard indentation tests. By analyzing the dependence of the cantilever deflection versus time, the proposed technique allows one to evaluate and correct the effect of viscoelastic properties of the investigated materials, by adapting a post-experiment data processing procedure well-established for standard depth sensing indentation tests. The technique is described in the case of the measurement of indentation modulus and hardness of a thin film of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate), deposited by chronoamperometry on an indium tin oxide (ITO) substrate.