Universal mean-field upper bound for the generalization gap of deep neural networks

Modern deep neural networks (DNNs) represent a formidable challenge for theorists: according to the commonly accepted probabilistic framework that describes their performance, these architectures should overfit due to the huge number of parameters to train, but in practice they do not. Here we employ results from replica mean field theory to compute the generalization gap of machine learning models with quenched features, in the teacher-student scenario and for regression problems with quadratic loss function. Notably, this framework includes the case of DNNs where the last layer is optimized given a specific realization of the remaining weights. We show how these results-combined with ideas from statistical learning theory-provide a stringent asymptotic upper bound on the generalization gap of fully trained DNN as a function of the size of the dataset P. In particular, in the limit of large P and N_{out} (where N_{out} is the size of the last layer) and N_{out}≪P, the generalization gap approaches zero faster than 2N_{out}/P, for any choice of both architecture and teacher function. Notably, this result greatly improves existing bounds from statistical learning theory. We test our predictions on a broad range of architectures, from toy fully connected neural networks with few hidden layers to state-of-the-art deep convolutional neural networks.

European Council of Legal Medicine (ECLM) on-site inspection forms for forensic pathology, anthropology, odontology, genetics, entomology and toxicology for forensic and medico-legal scene and corpse investigation: the Parma form

Further to a previous publication by the European Council of Legal Medicine (ECLM) concerning on-site forensic and medico-legal scene and corpse investigation, this publication provides guidance for forensic medical specialists, pathologists and, where present, coroners' activity at a scene of death inspection and to harmonize the procedures for a correct search, detection, collection, sampling and storage of all elements which may be useful as evidence, and ensure documentation of all these steps. This ECLM's inspection form provides a checklist to be used on-site for the investigation of a corpse present at a crime or suspicious death scene. It permits the collection of all relevant data not only for the pathologist, but also for forensic anthropologists, odontologists, geneticists, entomologists and toxicologists, thus supporting a collaborative work approach. Detailed instructions for the completion of forms are provided.

Criticality and conformality in the random dimer model

In critical systems, the effect of a localized perturbation affects points that are arbitrarily far from the perturbation location. In this paper, we study the effect of localized perturbations on the solution of the random dimer problem in two dimensions. By means of an accurate numerical analysis, we show that a local perturbation of the optimal covering induces an excitation whose size is extensive with finite probability. We compute the fractal dimension of the excitations and scaling exponents. In particular, excitations in random dimer problems on nonbipartite lattices have the same statistical properties of domain walls in spin glass. Excitations produced in bipartite lattices, instead, are compatible with a loop-erased self-avoiding random walk process. In both cases, we find evidence of conformal invariance of the excitations that is compatible with SLE_{κ} with parameter κ depending on the bipartiteness of the underlying lattice only.

Cooperative effects on the compaction of DNA fragments by the nucleoid protein H-NS and the crowding agent PEG probed by Magnetic Tweezers

BACKGROUND

DNA bridging promoted by the H-NS protein, combined with the compaction induced by cellular crowding, plays a major role in the structuring of the E. coli genome. However, only few studies consider the effects of the physical interplay of these two factors in a controlled environment.

METHODS

We apply a single molecule technique (Magnetic Tweezers) to study the nanomechanics of compaction and folding kinetics of a 6 kb DNA fragment, induced by H-NS bridging and/or PEG crowding.

RESULTS

In the presence of H-NS alone, the DNA shows a step-wise collapse driven by the formation of multiple bridges, and little variations in the H-NS concentration-dependent unfolding force. Conversely, the DNA collapse force observed with PEG was highly dependent on the volume fraction of the crowding agent. The two limit cases were interpreted considering the models of loop formation in a pulled chain and pulling of an equilibrium globule respectively.

CONCLUSIONS

We observed an evident cooperative effect between H-NS activity and the depletion of forces induced by PEG.

GENERAL SIGNIFICANCE

Our data suggest a double role for H-NS in enhancing compaction while forming specific loops, which could be crucial in vivo for defining specific mesoscale domains in chromosomal regions in response to environmental changes.

Informing MS patients on treatment options: a consensus on the process of consent taking

In the last years, change in multiple sclerosis (MS) therapeutic scenario has highlighted the need for an improved doctor-patient communication in advance of treatment initiation in order to allow patient's empowerment in the decision-making process. AIMS: The aims of our project were to review the strategies used by Italian MS specialists to inform patients about treatment options and to design a multicentre shared document that homogenizes the information about disease-modifying treatment (DMTs) and the procedure of taking informed consent in clinical practice. RESULTS: The new resource, obtained by consensus among 31 neurologists from 27 MS Centres in Italy with the supervision of a medico-legal advisor, received the aegis of Italian Neurological Society (SIN) and constitutes a step toward a standardized decision process around DMTs in MS.

Otoacoustic emission sensitivity to exposure to styrene and noise

The ototoxic effect of the exposure to styrene is evaluated, also in the presence of simultaneous exposure to noise, using otoacoustic emissions as biomarkers of mild cochlear damage. Transient-evoked and distortion product otoacoustic emissions were recorded and analyzed in a sample of workers (15 subjects) exposed to styrene and noise in a fiberglass manufacturing facility and in a control group of 13 non-exposed subjects. Individual exposure monitoring of the airborne styrene concentrations was performed, as well as biological monitoring, based on the urinary concentration of two styrene metabolites, the Mandelic and Phenylglyoxylic acids. Noise exposure was evaluated using wearable phonometers, and hearing loss with pure tone audiometry. Due to their different job tasks, one group of workers was exposed to high noise and low styrene levels, another group to higher styrene levels, close to the limit of 20 ppm, and to low noise levels. A significant negative correlation was found between the otoacoustic emission levels and the concentration of the styrene urinary metabolites. Otoacoustic emissions, and particularly distortion products, were able to discriminate the exposed workers from the controls, providing also a rough estimate of the slope of the dose-response relation between otoacoustic levels and styrene exposure.

Theta-point polymers in the plane and Schramm-Loewner evolution

We study the connection between polymers at the θ temperature on the lattice and Schramm-Loewner chains with constant step length in the continuum. The second of these realize a useful algorithm for the exact sampling of tricritical polymers, where finite-chain effects are excluded. The driving function computed from the lattice model via a radial implementation of the zipper method is shown to converge to Brownian motion of diffusivity κ=6 for large times. The distribution function of an internal portion of walk is well approximated by that obtained from Schramm-Loewner chains. The exponent of the correlation length ν and the leading correction-to-scaling exponent Δ_{1} measured in the continuum are compatible with ν=4/7 (predicted for the θ point) and Δ_{1}=72/91 (predicted for percolation). Finally, we compute the shape factor and the asphericity of the chains, finding surprising accord with the θ-point end-to-end values.

[Synergistic exposure to noise and styrene and cochlear functionality in a sample of exposed workers: preliminary results]

This study is aimed at testing the cochlear functionality using otoacoustic emissions, analyzing the synergistic effects of simultaneous exposure to noise and organic solvents EBTx on workers of a glass-reinforced plastic products factory. Exposure to organic solvents was assessed using ambiental measurements and evaluation of the salivary concentration. Biological monitoring was performed evaluating the urinary concentration of the styrene metabolites. Statistical analysis shows that otoacoustic tests can discriminate between different exposure groups. Significant differences were found between controls and subjects exposed to high styrene and low noise levels, showing the ototoxic effect (at sub-clinical level) of the styrene exposure.

Insects found on a human cadaver in central Italy including the blowfly Calliphora loewi (Diptera, Calliphoridae), a new species of forensic interest

In the case of unidentified bodies the estimation of the period since death or of the season of death plays an important role to focus the attention on a reduced number of people among the ones reported missing. Forensic entomology can be one of the most important methods for these estimations, as occurred in this case. Flies are typically the first insects to colonize a dead body. The case reported here concerns the colonisation by insects of a male body in advanced decay found during the winter in Central Italy. This case is of particular interest as few data are available on the entomological evidence in the cold season. In particular, in this case we recovered Calliphora loewi (Calliphoridae), a species never collected before on dead bodies in Southern Europe. Larvae of the black soldier fly Hermetia illucens (Stratiomyidae), pupae and larvae belonging to genus Hydrothea (Muscidae), and Necrobia rufipes (Cleridae) specimens were also collected. The estimated PMI enabled identification of the cadaver, confirmed by DNA analysis.

[Occupational exposure to hexavalent chromium during aircraft painting]

Hygienists are interested in hexavalent chromium due to its genotoxic and carcinogenic effect on humans. The use of products containing hexavalent chromium is decreasing in many industrial fields because of the substitution with less-toxic compounds. In the aeronautical industry, however, the chromate are added to primer paint as a corrosion inhibitor of aircrafts surfaces: so hexavalent chromium compounds are available in many primers with a composition ranging from 10% to 13%. The application of these primers by using electrostatic guns potentially exposes painting and coating workers at high concentrations of aerosols containing Cr(VI). The aim of the present study is the evaluation of professional exposure to hexavalent chromium during aircraft painting, by adopting both environmental personal sampling and biological monitoring. To valuate workers exposure levels the personal measurements results have been compared with the exposure limit values (TLV-TWA) and the urinary chromium contents with the biological exposure indices (IBE). Moreover the strategy of coupling environmental sampling with biological monitoring seems to be a useful instrument to measure the validity of the individual protection devices.

The epidermis of Timarete filigera (Polychaeta, Cirratulidae): histochemical and ultrastructural analysis of the gland cells

The aim of this study was to verify whether different living conditions of Polychaeta are correlated with morphological and functional differences in the organization of the integument. For this purpose, we decided to study the epidermis of Timarete filigera, a non-tubicolous polychaete. With this objective in mind, we have identified the various cellular types responsible for mucous secretion in the epidermis of this species and defined the histochemical composition of the mucus produced by different types of gland cells. Three types of gland cells have been identified by histochemical and ultrastructural studies in the epidermis of this polychaete. The histochemistry was carried out using standard techniques and peroxidase-labelled lectins. In type 1 cells, the secretory granules contain neutral glycoproteins with glucosidic residues of GalNAc, Galbeta 1,3 GalNAc, glucosidic and/or mannosidic residues. In type 2 cells, the secretory granules contain acid glycoproteins mainly sulphated with glucosidic residues of GalNAc, Galbeta 1,3 GalNAc, glucosidic and/or mannosidic residues, and some terminal sialic acid. In type 3 cells, the residual granules have the same chemical composition as that of granules present in type 2 cells. The secretion of these glandular mucous cells consists of mainly sulphated acidic glycoproteins and GAG resistant to testis jaluronidase. In these cells, the residual granules have the same chemical composition as that of their secretion. The heterogeneity of mucus composition may be correlated with its different functions.

[Chemical risk of exposure to volatile organic compounds in the field of restoration of art objects]

The use of chemicals during restoration practices involves emissions of toxics depending on both the amount of original products used and the specific techniques applied. Restorers perform a great variety of techniques by using not standardized operative procedures: moreover, they are exposed to mixtures and very rarely to single chemicals. In this study we evaluated workers' exposure to solvent mixture which were generated during restoration of archaeological metal handcraft. Exposure to low levels of twelve organic compounds has been experimented inside a public restoration laboratory: based on the data presented in this article we assume that inside restoration workplaces a diffused indoor contamination can take place. The indoor pollution can generate a risk of an uncontrolled exposure to volatile mixtures: therefore the emissions of solvents during restoration practices has to be avoided even if they cause a low level of exposure.

The diagnosis of amniotic fluid embolism: an immunohistochemical study for the quantification of pulmonary mast cell tryptase

Recent clinical articles have suggested that amniotic fluid embolism (AFE) may be the result of anaphylactic reactions to fetal antigens and that the major part of this clinical syndrome is the result of mast cell degranulation and of the release of histamine, tryptase and other mediators. Tryptase, a neutral protease, is known to be the dominant protein component of the secretory granules of T and TC mast cells. In this paper we have examined the presence and the pulmonary distribution of mast cell tryptase utilizing specific immunohistochemical studies and morphometric evaluation in six cases of fatal amniotic fluid embolism compared to six subjects who died following anaphylactic shock and two control groups (five and six cases respectively) of traumatic death. The results demonstrate a numerical increase of pulmonary mast cells in the subjects who died of AFE (average cell number 54.095) with values corresponding to those encountered in cases of death due to anaphylactic shock (average cell number 51.378) compared with that of the traumatic control groups (average cell number 24.477 and 9.995 respectively). These results can shed light on additional criteria for the diagnosis of amniotic fluid embolism.

Movement-induced seizures: a case report

Reflex seizures induced by movement are typically evoked by sudden or unattended motor actions. However, tonic seizures may also be triggered by slow movements as observed in nonketotic hyperglycemia or in "praxis-induced epilepsy." We report the case of a young, nondiabetic patient affected by recurrent partial tonic postural seizures precipitated by slow movements which were unrelated to cognitive tasks. Ictal EEG did not permit location of the epileptogenic brain region. However, the clinical features suggest possible involvement of the supplementary motor area.

Intramammary immunization with live-attenuated Staphylococcus aureus: microbiological and immunological studies in a mouse mastitis model

Mammary infection was induced in lactating mice by intramammary injection of Staphylococcus aureus. Histopathological analysis revealed infiltration and lesions of varying magnitude that were still apparent 21 days after the challenge. Concomitantly, viable S. aureus was recovered from infected mammary glands. Mice were immunized by the intramammary route with 5 x 10(6) colony forming units of a temperature-sensitive mutant of S. aureus and subsequently received a boosting injection seven days later. On day 14 mice were challenged by the intramammary route with the wild-type strain. Intramammary immunization induced a significant increase in milk IgA (P < 0.05), serum IgG (P < 0.05) and serum IgA (P < 0.05) on the day of the challenge, when compared with non-immunized mice. Immunization decreased significantly (P < 0.01) the number of S. aureus colony forming units recovered 96 h after intramammary challenge. In conclusion, the feasibility of immunizing locally with temperature-sensitive S. aureus to induce immunity in the mouse mammary gland was demonstrated. The mouse model of mastitis is proposed as a useful system for screening temperature-sensitive S. aureus strains to be utilized in the development of a vaccine.

Ultrastructural study of the mature egg of the marine sponge Stelletta grubii (Porifera Demospongiae)

Stelletta grubii is an oviparous demosponge, which, during its reproductive period from summer to autumn, has small eggs (80-90 microns) dispersed uniformly in the mesohyl. The nucleolated nucleus is surrounded by dictyosomes containing small vesicles, which contribute to form reserve material. Vesicles, numerous food vacuoles, and groups of mitochondria are observed in the granular cytoplasm. Electron-dense yolk inclusions and lipids are found peripherally. The cortical portion of the egg cytoplasm possesses vacuoles with fibrillar contents. The egg forms pseudopodia, which could permit the capture of numerous bacteria present in the surrounding mesohyl. A thick layer of collagen fibrils, including lophocytes, separates the egg from the surrounding sponge mesohyl. Ultrastructural analysis has demonstrated the presence both of cellular components capable of autosynthetic activity (nutrient vesicles) and of phagocytosis mechanisms (pseudopod capture of bacteria) for the storage of nutrients by the egg.

A new symbiotic cluster on the pSym megaplasmid of Rhizobium meliloti 2011 carries a functional fix gene repeat and a nod locus

A 290-kilobase (kb) region of the Rhizobium meliloti 2011 pSym megaplasmid, which contains nodulation genes (nod) as well as genes involved in nitrogen fixation (nif and fix), was shown to carry at least six sequences repeated elsewhere in the genome. One of these reiterated sequences, about 5 kb in size, had previously been identified as part of a cluster of fix genes located 220 kb downstream of the nifHDK promoter. Deletion of the reiterated part of this fix cluster does not alter the symbiotic phenotype. Deletion of the second copy of this reiterated sequence, which maps on pSym 40 kb upstream of the nifHDK promoter, also has no effect. Deletion of both of these copies however leads to a Fix- phenotype, indicating that both sequences carry functionally reiterated fix gene(s). The fix copy 40 kb upstream of nifHDK is part of a symbiotic cluster which also carries a nod locus, the deletion of which produces a marked delay in nodulation.

Identification of Streptococcus pneumoniae mismatch repair genes by an additive transformation approach

During transformation of Streptococcus pneumoniae, mismatch repair occurs on donor-recipient heteroduplexes harboring some mismatched base pairs. A few mutants defective in mismatch repair have been isolated and termed hex-. However, neither the number of genes involved nor their products have yet been identified. In an attempt to characterize such genes we have used an additive transformation approach--that is the inactivation of genes by insertion of chimeric plasmids. Pneumococcal DNA fragments were joined in vitro to a plasmid derivative of pBR325 that carries an erythromycin resistance determinant and does not replicate autonomously in S. pneumoniae. Ery-r transformants obtained with such a ligation mixture arise via homology-dependent integration of the chimeric plasmids into the chromosome. Hex- mutants have been selected among the ery-r population. Comparison of these mutants by Southern blot hybridization with a vector probe reveals that at least two genes are involved in mismatch repair.

Genetic variants of human glucose-6-phosphate dehydrogenase in a Saharian and Pygmy family

In two African communities, inhabitants of a Western Sahara oasis and Bi-Aka Pygmies (Central Africa), a genetic study of the distribution of G6PD phenotypes has been undertaken. Obtained data show the existence in both groups of slow electrophoretic variants with no enzyme deficiency or moderately reduced activity. Biochemical characterization of G6PD types was performed. In the Saharian family in which inheritance pattern of mutant G6PD was investigated, two alleles were found, the Negroid marker GdA- and Gd+Madrona, segregating among the different members. In the Pygmy family the Gd+Ibadan-Austin gene was detected. The incidence of these mutations in the groups studied, a comparison with similar G6PD variants observed in other African populations and the geographic distribution of these slow molecules are discussed in this paper.

Red cell and serum enzymes of Guinea baboon (Papio papio)

Variants of some erythrocyte and serum enzymes have been studied among several blood samples of Guinea baboon (Papio papio). Variation occurred in two red cell enzymes, G6PD and NADH diaphorase, and in serum esterase. All studied animals had a complete uniformity in other enzyme systems (acP, 6PGD, CA, AK, and cholinesterase at E1 locus). Data obtained in the present work have been discussed and compared with those reported among other baboon species.

Heterogeneity of erythrocyte pyruvate kinase deficiency and related metabolic disorders in patients with hematological diseases

In several patients suffering from congenital non-spherocytic hemolytic anemia or from malignant hemotological disorder associated with erythrocyte pyruvate kinase (PK) deficiency, a metabolic study has been carried out involving the following biochemical determinations: assay of red cell enzyme activities; estimation of glucose consumption; measurement of the rate of glycolytic intermediates; and, in some cases, enzyme purification and characterization of the PK variant. Metabolic equilibrium most probably does not depend on kinetic characteristics of PK molecules. Furthermore, the data obtained allow separation of cases with congenital non-spherocytic hemolytic anemia (hereditary defect) and acquired PK deficiencies.

G6PD Lozere and Trinacria-like. Segregation of two non hemolytic variants in a French family

Two new G6PD variants have been found in red blood cells of the members of a French family originating from Lozere. The father is hemizygous for an electrophoretically fast variant with mild enzyme deficiency (50--60% of normal). The abnormal paternal G6PD gene is segregating in his daughter who is double heterozygous for maternal and paternal variants. This mutant enzyme, different from previously described variants is designated as Gd Lozere. The mother is heterozygous for another G6PD variant. Two sons are hemizygous for this latter mutant enzyme characterized by a moderate deficiency (25--30% of normal) and slower electrophoretic mobility with some slightly altered kinetic properties. This G6PD had been identified as Gd Trinacria like. These two abnormal enzymes are not associated with any hemolytic problem. Case reported is the first showing the segregation of two new mutant enzymes, distinct from common G6PD variants, among the members of the same family.

Distribution of G6PD types in the population of southwest France: common variants and new variants

Glucose-6-phosphate dehydrogenase was purified from blood samples originating from 33 subjects living in the 'Midi-Pyrenees' region (Southwest France). Biochemical and electrophoretic characteristics of several enzymatic variants were revealed. The distribution of the mutations in the subjects studied gave the following results: (1) Meditteranean Gd(-) and Gd(-)A identified variants; they constitute the main part of our observations. (2) Two original variants confirmed by the WHO International Reference Laboratory, that is: Gd(-) Toulouse and Gd(+) Luz-Saint-Sauveur; the latter mutation did not produce any haematological disorder. Absence of chronic haemolytic anaemia as well as a high rate of favism could be found in the families studied. As it is generally observed in Mediterranean regions, Southwest France population is characterized by a certain heterogeneity in biochemical and genetic mutations.

Serum and red cell enzyme variants in an Amerindian tribe: the Sirionos (Eastern Bolivia)

Blood samples from 109 Siriono (Eastern Bolivia) belonging to the Tupi-Guarani group were investigated for enzyme variants in the following systems: glucose-6-phosphate dehydrogenase, phosphogluconate dehydrogenase, adenylate kinase, phospho-glucomutase (locus 1 and 2), acid phosphatases, lactate dehydrogenase, NADH diaphorase, pseudocholinesterase (E1 and E2 locus), and serum alkaline phosphatase. The most relevant observations are: (1) A relative lack of polymorphism, a characteristic feature of the Amerindian populations studied up to now. These data are consistent with the hypothesis of a 'common ancestral background' in Indian populations whatever the degree of sociocultural and linguistic diversity, and the geographical distances. (2) Specific traits due to the frequency of alleles in some systems confer to that tribe a particular position among Amerindians. The effects of genetic drift may be postulated in order to explain the high rate of PGM and 6PGD polymorphism. Furthermore, in that small community, the disappearance of some alleles (pa gene) can plausibly be explained in terms of a balanced influence of mutational and selective pressure.

Erythrocyte glucose-6-phosphate dehydrogenase in the Niokolonko (Malinke of the Niokolo) of Eastern Senegal. Identification of a slow variant with normal activity (Tacoma-like)

In a survey of blood genetic markers in the Niokolonko of Eastern Senegal, three types of G6PD variants were discovered: (1) fast variants, common Negro G6PD A +; the frequency of the Gd A + gene was 0.183; (2) deficient G6PD A--, occurring with a fairly low frequency: 0.079, and (3) some individuals were carriers of a slow moving electrophoretic variant with normal activity. After purification, the analysis of kinetic parameters showed that this enzyme was closely similar to G6PD Tacoma. We proposed to label it 'G6PD Tacoma-like'. The incidence of this mutation in the whole group studied was 0.020. G6PD Tacoma-like may be common in some African tribes.

Induction of filament formation and thymineless death in Escherichia coli K-12

The study of isogenic strains of Escherichia coli K-12 carrying mutations which control filament formation after ultraviolet irradiation showed that there is not necessarily a relationship between filament formation and thymineless death.