Showing papers by "Sapienza University of Rome published in 1983"

A Theory of Stochastic Resonance in Climatic Change

Abstract: In this paper we study a one-dimensional, nonlinear stochastic differential equation when small amplitude, long-period forcing is applied. The equation arises in the theory of the climate of the earth. We find that the cooperative effect of the stochastic perturbation and periodic forcing lead to an amplification of the peak of the power spectrum, due to a mechanism that we call stochastic resonance. A heuristic analysis of the resonance condition is presented and our analytical findings are confirmed by numerical calculations.

Intradural spinal cysts.

Abstract: 18 cases of benign intradural spinal cyst (9 arachnoidal, 2 neuroepithelial, 7 endodermal) are reported and compared with 94 cases (67 arachnoidal, 7 neuroepithelial, 20 endodermal) obtained from the literature.

Predictive value of cord blood IgE levels in ‘at‐risk’ newborn babies and influence of type of feeding

Abstract: Cord serum IgE levels were examined in 101 newborn infants of atopic parents, and reviewed at the ages of 3, 6, 9, 12, 15, 18, 21 and 24 months, in order to determine any relation with signs and symptoms of allergic rhinitis, bronchial asthma, atopic dermatitis, urticaria and food allergy. Cord blood IgE levels were 1.06 +/- 1.02 U/ml in the group of infants who developed atopic disease, and 0.34 +/- 0.79 U/ml in the group of infants who did not develop atopy (P less than 0.001). In the breast-fed group 37.5% of the infants with cord blood IgE more than 0.8 U/ml and 11.5% with IgE below 0.8 U/ml had atopic disease. In the soy-fed group 33.3% of the infants with cord blood IgE more than 0.8 U/ml and 15.8% with cord blood IgE less than 0.8 U/ml developed atopy. Ninety percent of the cow's milk-fed infants with cord blood IgE above 0.8 U/ml and 16% with cord blood IgE below 0.8 U/ml showed atopy during the follow-up period. No correlation was found between the IgE levels in maternal and respective cord blood.

Familial incidence of twinning

Abstract: The frequency of twinning among women who have already borne twins, the 'repeat frequency', is significantly higher than in the general population. Individual propensity is not necessarily genetic in origin, but pedigree studies (for reviews see refs 1, 2) confirm that twinning is a family trait. Studies based on archives restrict this conclusion to dizygotic (DZ) twinning and the maternal side, while studies based on interviews of relatives of twins find monozygotic (MZ) twinning and the paternal side also to be involved. However, interview studies can overestimate, while archive studies can underestimate, the real frequency of twinning. We have now analysed the incidence of twinning in the families of 950 zygosity-determined, unselected twin pairs under complete ascertainment. Our results indicate that a propensity to MZ twinning, as well as one to DZ twinning, can be inherited through the maternal line, and that the two mechanisms of twinning might be related. We have also found a paternal role in DZ, but not in MZ twinning.

Graph Algorithms for Functional Dependency Manipulation

Abstract: . A graph-theoretic approach for the representation of functional dependenoes in relauonal databases is introduced and applied in the construction of algorithms for manipulating dependencies. This approach allows a homogeneous treatment of several problems (closure, minimization, etc.), which leads to simpler proofs and, m some cases, more efficient algorithms than in the current literature. Categories and Subject Descriptors: F.2.2 [Analysis of Algorithms and Problem Complexity]: Nonnumencal Algorithms and Problems--computations on d, screte structures; G.2.2 [Diserete Mathematics]: Graph Theory--graph algorithms; H.2.1 [Database Management]: Logical Design-normal forms; schema and subschema General Terms: Algorithms, Design, Management, Theory Additional Key Words and Phrases: Closure, computational complexity, functional dependency, FD- graph, minimal coverings, relational database 1. Introduction

Effect of low-dose acute X-irradiation on the frequencies of chromosomal aberrations in human peripheral lymphocytes in vitro

Abstract: In a coordinated research programme sponsored by the Internation Atomic Energy Agency, the frequencies of chromocomal aberrations induced in peripheral blood lymphocytes (in vitro) by 250 kV X-rays at low doses (04, 1, 2, 3, 5, 10 and 30 rad) were determined Blood from 2 donors was used to conduct one master experiment at these dose levels The culture time used was 48 h and all samples including the controls were processed according to a standard protocol The coded slides were scored by investigators from 10 participating laboratories The main results are the following: (1) the frequencies of all types of chromosome aberrations at 04 rad are significantly lower than the control values; (2) there is no increase in the frequencies of dicentrics up to 2 rad and in those of terminal deletions up to 5 rad; (3) the mean frequencies of all aberrations considered together are not significantly different from one another at 1,2 and 3 rad ( P = 005); and (4) over the entire dose range the dose-effect relationship is clearly non-linear A fit of these data to a linear quadratic model ( E ( D ) = c + αD + βD 2 ) showed that the observed total aberration frequencies at doses 1,2,3 and 5 rad are below the curve defined by the model The deviations can be explained by an altered kinetics of aberration production at very low doses probably due to DNA repair mechanisms operating in these cells

Distribution of osteonic and interstitial components in the human femoral shaft with reference to structure, calcification and mechanical properties

Abstract: This paper analyzes the distribution of osteons and interstitial bone in the femoral compacta according to their structure, degree of calcification and mechanical properties. Three cross sections, 100 microns thick, each located 1 cm from the next, were prepared by grinding from the middle third of a human femoral shaft. Starting from the premise that, in lamellar bone, lamellae whose fiber bundles and crystallites have a longitudinal course withstand loading by tension, whereas those whose fiber bundles and crystallites have a transversal course withstand loading by compression, each osteon and fragment of interstitial bone has been given a number recording the percentage of its surface consisting of lamellae with transversally oriented fiber bundles and crystallites (bright under the polarizing microscope). The degree of calcification of the same structures was determined micro-radiographically. The distribution of both osteons and interstitial bone was assessed using a tungsten grid for reference. The total surface of each bone microstructure, and the percentage of that surface consisting of bright lamellae, were all calculated using a Zeiss Video-plan. Our results confirm the view that the distribution of both osteons and interstitial bone is mainly related to their structure--and hence to their mechanical properties. In addition, bone remodeling seems to be most active in areas capable of supporting tensile stress.

Quantum theory of measurement without wave packet collapse

Abstract: A schematization of the measurement process in quantum mechanics is presented leading to the conclusion that the wave packet collapse should not be considered an additional postulate extraneous to the theory, but rather an approximate consequence of the standard Schrodinger time evolution. The equivalence - up to any conceivable level of accuracy - between the pure state vector of the total system “object + apparatus” and the statistical matrix representing the possible outcomes of the measurement, shows that the observer by no means determines its result, but merely obtains all the statistical information available from a description of the object together with the relevant part of the physical world interacting with it.

Human Interferon-γ Enhances the Expression of Class I and Class II Major Histocompatibility Complex Products in Neoplastic Cells More Effectively than Interferon-α and Interferon-β

Abstract: Human interferon-γ was more effective than interferon-β or -α in stimulating production of immunoassociated antigens; HLA-A, -B, and -C; and β2-microglobulin in human M14 and Namalva cells. The comparison was made on the basis of antiviral units, and the stimulation could be abolished by treatment of the interferon-γ preparation with pH 2 or anti-interferon-γ serum.

Instigation to aggress and escalation of aggression examined from a personological perspective: The role of irritability and of emotional susceptibility

Abstract: Two studies were conducted using Buss hostility machine paradigm to investigate the role of individual differences in irritability and emotional susceptibility on the instigation to aggress by a self-esteem lowering manipulation and on the hypothesized escalation of aggression over trials. The role of sex was also examined. In the first study, 60 highly irritable and 60 low irritable subjects were given the opportunity to deliver electric shocks to an experimental confederate, half after being provoked by a negative judgement on their performance in a learning task, half without such an experience. Each group of subjects was divided equally between males and females. It was found that highly irritable subjects, both males and females, delivered higher shocks after provocation than low irritable subjects under similar circumstances. An upward drift of shock level over trials was found only in provoked males and only in highly irritable females. In the second study, 60 highly emotionally susceptible and 60 low emotionally susceptible males and females were given the opportunity to deliver electric shocks to an experimental confederate, half after experiencing provocation, half without such an experience. It was found that provoked subjects delivered higher shocks than unprovoked subjects and that highly emotionally susceptible subjects delivered higher shocks than low emotionally susceptible subjects. Whereas an upward drift of shock levels over trials was found only in provoked males, the same effect was found in females, whether provoked or not. These findings are discussed in terms of the importance of stable personality characteristics that may mediate aggressive response.

Euler evolution for singular initial data and vortex theory

Abstract: We study the evolution of a two dimensional, incompressible, ideal fluid in a case in which the vorticity is concentrated in small, disjoint regions of the physical space. We prove, for short times, a connection between this evolution and the vortex model.

Labeled aryl fluorides from the nucleophilic displacement of activated nitro groups by 18F‐F−

Abstract: Nucleophilic displacement of activated nitro groups by 18F-fluoride ion is an efficient route to fluorine-18 labeled aromatics, which can be obtained in the no-carrier-added state if required. The basic features of the fluorodenitration process are comparatively evaluated, and the influence of the experimental variables on its course are discussed. Examples concerning the preparation of typical 18F-labeled aromatic molecules are reported.

Relaxation to different stationary states in the Fermi-Pasta-Ulam model

Abstract: The Fermi-Pasta-Ulam model has been studied following the time evolution of the space Fourier spectrum through the numerical integration of the equations of motion for a system of 128 non-linearly coupled oscillators. One-mode and multimode excitations have been considered as initial conditions; in the former case, an approximate analytic technique has been applied to describe the "short-time" behavior of the system, which fits well the experiment. The main result in both cases is the presence of different stationary states towards which the system is evolving: a $\frac{1}{{k}^{2}}$ spectrum (corresponding to the equipartition of energy) or an exponential spectrum can be reached, depending on the value of some parameter, which takes into account the relative weight of the nonlinear to the linear term of the equations of motion.

Primary immunodeficiency syndromes in Italy: A report of the national register in children and adults

Abstract: The Italian Register for Immune Deficiencies was organized in 1977 Seven hundred ninety-seven cases of primary immunodeficiencies, diagnosed according to the World Health Organization criteria, have been registered up to April 1982 In this paper we report the percentages of the different forms of primary immunodeficiencies and the incidence of neoplastic and autoimmune diseases A prevalence of humoral defects and selective IgA deficiency was found, followed by T-cell disorders Two and thirty-eight hundredths percent of the patients developed cancer, and 589% developed autoimmune diseases A comparison among the Italian, Swedish, and Japanese Registers showed a higher incidence of IgA defects in the Italian Register while nonspecific phagocyte defects were more frequent in the Swedish Register The incidence of cancer and autoimmune disorders is similar to that observed in other registers

The orbicularis oculi response after hemispheral damage.

Abstract: The corneal and blink reflexes were evaluated in 20 normal subjects and in 30 patients with motor deficits secondary to unilateral hemispheral lesions of vascular origin. In the normal population there were no differences between subjects below and subjects above 50 years of age. In the patients the reflex evoked by electrical stimulation of the cornea of the clinically affected side was depressed in 24 out of 30 cases. The depression mainly affected the afferent branch of the circuit, which triggers both homolateral and contralateral orbicularis oculi discharge (afferent abnormality). In three cases the depression was exerted concomitantly on the efferent branch (afferent and efferent abnormality) and only in one case was it limited to the efferent branch (efferent abnormality). The late R2 component of the blink reflex was depressed in 15 out of 30 patients. The early R1 component was slightly facilitated on the affected side. The changes of the corneal reflex and of the R2 component of blink reflex were similar, but the blink reflex had a greater safety factor. The patients with an abnormal corneal reflex had more extensive damage than had the patients with normal corneal response, as shown by computer tomography, but the site of the lesion was comparable in the two groups. Conduction through the brain stem circuits mediating the orbicularis oculi response is normally under pyramidal facilitatory influences while facial motoneurons are subjected to pyramidal inhibition. After pyramidal damage the transmission of impulses in the brain stem was slowed down, ultimately to a degree that abolished the reflex. Removal of pyramidal inhibition on facial motoneurons is probably the basis of the slight facilitation of the R1 component of the blink reflex.

A model of anisotropic grain-oriented steel

Abstract: In this work the magnetic flux distribution in the grain-oriented steel core transformer is investigated with the finite element method. A mathematical model (Model II) is obtained for the reluctivity tensor. The model, optimized by means of experimental values of the B-H curve, predicts different directions of the magnetization field, not just along the rolling and transverse directions of the material. The results are the flux maps, as well as the reactance values and the electrodynamic forces on the windings. These results, obtained by means of the isotropic model and the anisotropic first model [1], are compared with the experimental ones.

Immune abnormalities in diabetic patients not requiring insulin at diagnosis

Abstract: Islet cell antibodies (ICA), complement fixing islet cell antibodies, immune complexes and thyro-gastric autoantibodies were studied in newly diagnosed diabetic patients not requiring insulin at diagnosis. Particular attention was focussed on that minority of patients who are initially treated with diet or oral agents but show ICA in their serum. One hundred and six non-insulin-requiring patients were studied at clinical diagnosis. Seventeen who had ICA in their serum were compared with a control group of 89 who did not. The 17 ICA-positive diabetic patients were followed serologically for approximately 1 year from diagnosis. Patients were followed clinically for 3 years. Forty-seven percent of ICA-positive and 19% of ICA-negative patients had immune complexes in their serum. Eleven of the 17 ICA-positive patients also had serum complement fixing islet cell antibodies. Thyro-gastric antibodies were found in 29% of ICA-positive and 18% of ICA-negative diabetic patients. ICA, complement fixing antibody and immune complex positivity declined with time. Ten of the 17 ICA-positive and two of the 89 ICA-negative patients required insulin within 3 years of diagnosis. There was a positive trend for the presence of complement fixing islet cell antibodies at diagnosis to be associated with the early development of insulin dependency. The type of diabetes in ICA-positive patients not requiring insulin at diagnosis has strong immunological and clinical similarities to classical Type 1 (insulin-dependent) diabetes.

Nucleotide sequence and intron structure of the apocytochrome b gene of Neurospora crassa mitochondria.

Abstract: The sequence of the apocytochrome b (cob) gene of Neurospora crassa has been determined. The structural gene is interrupted by two intervening sequences of approximately 1260 bp each. The polypeptide encoded by the exons shows extensive homology with the cob proteins of Aspergillus nidulans and Saccharomyces cerevisiae (79% and 60%, respectively). The two introns are, however, located at sites different from those of introns in the cob genes of A. nidulans and S. cerevisiae (which contain highly homologous introns at the same site within the gene). The introns share several short regions of sequence homology (10-12 bp long) with each other and with other fungal mitochondrial introns. Moreover, the second intron contains a 50 nucleotide long sequence that is highly homologous with sequences within every ribosomal intron of fungal mitochondria sequenced to date. The conserved sequences may allow the formation of a core secondary structure, which is nearly identical in many mitochondrial introns. The conserved secondary structure may be required for intron splicing. The second intron contains an open reading frame, continuous with the preceding exon, of approximately 290 codons. Two stretches of 10 amino acid residues, conserved in many introns, are present in the open reading frame.

Genotype-environment relationships: an analysis of stature distribution curves during the last century in Italy

Abstract: The secular trend of stature in Italy from 1874 to 1960 has been examined using military records concerning nearly complete samples of males born in Italy in given years. The national mean value increased by nine cm (about one cm/decade) and the averages of the different Italian regions tend progressively to aggregate towards higher values (the north) and lower ones (the south). The rate of increase of stature was more or less constant up to subjects born in 1945, but in the period 1945-55 a very steep increase was observed. In more recent times, a clear slowing down has taken place both at national and regional level. The following moments around the mean were investigated: (1) variance--the national value has remained more or less constant and regional values pass from very diverse figures to very similar ones; (2) skewness--the initially negative national value has become slightly positive; in the regions, from very diverse negative values a close aggregation around zero is recently attained; (3) kurtosis--initial national hyperkurtosis has reduced to values typical of the Normal distribution; the same is true for regional figures which, moreover, have become closely aggregated. The increasing fit of stature distribution to the Normal distribution agrees with the hypothesis of an increasing expression of the genetic endowment in consequence of a progressive improvement in living conditions.

Involvement of Phosphodiesterase in the Refractoriness of the Sertoli Cell

Abstract: Gonadotropin treatment of the Sertoli cell produces a marked refractory state of the cell to subsequent hormonal stimulation. Because FSH also stimulates the phosphodiesterase activity of these cells, the possible involvement of an altered cAMP catabolism during refractoriness was investigated in an in vitro model. Sertoli cells, after 3 days of culture in a defined medium, were exposed to FSH or isoproterenol for 1-24 h. After this pretreatment, cells were stimulated for 1 h with a maximal FSH dose, and the responsiveness was measured in terms of cAMP accumulation. Sertoli cells previously treated with hormone entered a refractory state, a second exposure being ineffective in elevating intracellular or extracellular cAMP. Addition of the phosphodiesterase inhibitor 3-isobutyl-methylxanthine in the second incubation partially restored the ability of the cell to accumulate cAMP in the presence of hormone. This phosphodiesterase inhibitor also caused an apparent decrease in the potency of FSH to induce the refractory state. Such an impairment of response developed in the intact cell in 4 h, and was accompanied by a partial desensitization of the adenylate cyclase and an increase in phosphodiesterase activity. The stimulation of phosphodiesterase activity, but not the desensitization of adenylate cyclase, was inhibited by cycloheximide. The inhibition of protein synthesis also prevented the onset of the refractory state of the intact Sertoli cell. Pretreatment of the Sertoli cells with either FSH or isoproterenol rendered the cell refractory to a second stimulation with either agonist; in contrast, the adenylate cyclase desensitization in the homogenate was apparent only for the agonist employed in the preincubation. These results indicate that phosphodiesterase regulation is involved in the control of Sertoli cell responsiveness to hormone. Thus, the net decrease in cAMP production of the FSH-treated cells is the result of a decreased adenylate cyclase stimulation and an increased cAMP catabolism mediated by phosphodiesterase. The latter phenomenon appears to be the predominant cause of the partial refractoriness induced by low doses of gonadotropin.

Heterogeneity of immunological abnormalities in ataxia-telangiectasia.

Abstract: Peripheral blood mononuclear cells from five patients with ataxia-telangiectasia were evaluated for their reactivity with a panel of monoclonal antibodies directed against T-cell subsets and for theirin vitro functions in a pokeweed mitogen-induced immunoglobulin biosynthesis assay. All the patients had significantly reduced proportions of cells identified by monoclonal antibodies to subpopulations of T lymphocytes with helper activity (OKT4 and 5/9) and produced low amounts or no IgA and IgGin vitro. Immunoglobulin biosynthesis was increased by the addition of normal x-irradiated peripheral blood mononuclear cells in one of three patients, suggesting a helper T-cell deficiency in this patient and intrinsic B-cell defects in the other two. Two patients had increased proportions of cells identified by a monoclonal antibody to a subpopulation of T lymphocytes which includes suppressor T cells (OKT8), and their cells were able to suppress immunoglobulin biosynthesis by peripheral blood mononuclear cells from normal donors. These findings indicate heterogeneous disturbances of immunoregulatory mechanisms in ataxia-telangiectasia.