Observation of Light Thermalization to Negative-Temperature Rayleigh-Jeans Equilibrium States in Multimode Optical Fibers.

Although the temperature of a thermodynamic system is usually believed to be a positive quantity, under particular conditions, negative-temperature equilibrium states are also possible. Negative-temperature equilibriums have been observed with spin systems, cold atoms in optical lattices, and two-dimensional quantum superfluids. Here we report the observation of Rayleigh-Jeans thermalization of light waves to negative-temperature equilibrium states. The optical wave relaxes to the equilibrium state through its propagation in a multimode optical fiber-i.e., in a conservative Hamiltonian system. The bounded energy spectrum of the optical fiber enables negative-temperature equilibriums with high energy levels (high-order fiber modes) more populated than low energy levels (low-order modes). Our experiments show that negative-temperature speckle beams are featured, in average, by a nonmonotonic radial intensity profile. The experimental results are in quantitative agreement with the Rayleigh-Jeans theory without free parameters. Bringing negative temperatures to the field of optics opens the door to the investigation of fundamental issues of negative-temperature states in a flexible experimental environment.

Classical Rayleigh-Jeans Condensation of Light Waves: Observation and Thermodynamic Characterization.

Theoretical studies on wave turbulence predict that a purely classical system of random waves can exhibit a process of condensation, which originates in the singularity of the Rayleigh-Jeans equilibrium distribution. We report the experimental observation of the transition to condensation of classical optical waves propagating in a multimode fiber, i.e., in a conservative Hamiltonian system without thermal heat bath. In contrast to conventional self-organization processes featured by the nonequilibrium formation of nonlinear coherent structures (solitons, vortices,…), here the self-organization originates in the equilibrium Rayleigh-Jeans statistics of classical waves. The experimental results show that the chemical potential reaches the lowest energy level at the transition to condensation, which leads to the macroscopic population of the fundamental mode of the optical fiber. The near-field and far-field measurements of the condensate fraction across the transition to condensation are in quantitative agreement with the Rayleigh-Jeans theory. The thermodynamics of classical wave condensation reveals that the heat capacity takes a constant value in the condensed state and tends to vanish above the transition in the normal state. Our experiments provide the first demonstration of a coherent phenomenon of self-organization that is exclusively driven by optical thermalization toward the Rayleigh-Jeans equilibrium.

Decoupled polarization dynamics of incoherent waves and bimodal spectral incoherent solitons.

We consider the propagation of strongly incoherent waves in optical fibers in the framework of the vector nonlinear Schrödinger equation (VNLSE) accounting for the Raman effect. On the basis of the wave turbulence theory, we derive a kinetic equation that greatly simplifies the VNLSE and provides deep physical insight into incoherent wave dynamics. When applied to the study of polarization effects, the theory unexpectedly reveals that the linear polarization components of the incoherent wave evolve independently from each other, even in the presence of weak fiber birefringence. When applied to light propagation in bimodal fibers, the theory reveals that the incoherent modal components can be strongly coupled. After a complex transient, the modal components self-organize into a vector spectral incoherent soliton: The two solitons self-trap and propagate with a common velocity in frequency space.

Influence of a random phase plate on the growth of the backward stimulated Brillouin scatter.

We derive the analytical dispersion relation of a high-energy laser beam's backward stimulated Brillouin scattering (BSBS) in a hot plasma, that accounts both for the random phase plate (RPP) induced spatial shaping and its associated phase randomness. Indeed, phase plates are mandatory in large laser facilities where a precise control of the focal spot size is required. While the focal spot size is well controlled, such techniques produce small scale intensity variations that can trigger laser-plasma instabilities such as BSBS. Quantifying the resulting instability variability is shown to be crucial for understanding accurately the backscattering temporal and spatial growth as well as the asymptotic reflectivity. Our model, validated by means of a large number of three-dimensional paraxial simulations and experimental data, offers three quantitative predictions. The first one addresses the temporal exponential growth of the reflectivity by deriving and solving the BSBS RPP dispersion relation. A large statistical variability of the temporal growth rate is shown to be directly related to the phase plate randomness. Then, we predict the portion of the beam's section that is absolutely unstable, thus helping to precisely assess the validity of the vastly used convective analysis. Finally, a simple analytical correction to the plane wave spatial gain is extracted from our theory giving a practical and effective asymptotic reflectivity prediction that includes the impact of phase plates smoothing techniques. Hence, our study sheds light on the long-time studied BSBS, deleterious to many high-energy experimental studies related to the physics of inertial confinement fusion.

Viral encephalopathy and retinopathy outbreak in freshwater fish farmed in Italy.

Viral encephalopathy and retinopathy (VER), otherwise known as viral nervous necrosis (VNN), is a neuropathological condition affecting > 40 species of fish. Although VER affects mainly marine fish, the disease has also been detected in certain species reared in freshwater environments. There are relatively few reports concerning the disease in freshwater species, and there is not much information on clinical signs. Nevertheless, the most common clinical findings reported from affected freshwater species are consistent with the typical signs observed in marine species. In this paper we describe the main clinical signs and the laboratory results associated with the detection of a betanodavirus in hybrid striped bass x white bass (Morone saxatilis x Morone chrysops) and largemouth bass Micropterus salmoides, reared in a freshwater environment. We also detected the virus by real-time PCR and isolated it in cell culture from a batch of pike-perch Sander lucioperca farmed in the same system.

The central role of Italy in the spatial spread of USUTU virus in Europe.

USUTU virus (USUV) is an arbovirus maintained in the environment through a bird-mosquito enzootic cycle. Previous surveillance plans highlighted the endemicity of USUV in North-eastern Italy. In this work, we sequenced 138 new USUV full genomes from mosquito pools (Culex pipiens) and wild birds collected in North-eastern Italy and we investigated the evolutionary processes (phylogenetic analysis, selection pressure and evolutionary time-scale analysis) and spatial spread of USUV strains circulating in the European context and in Italy, with a particular focus on North-eastern Italy. Our results confirmed the circulation of viruses belonging to four different lineages in Italy (EU1, EU2, EU3 and EU4), with the newly sequenced viruses from the North-eastern regions, Veneto and Friuli Venezia Giulia, belonging to the EU2 lineage and clustering into two different sub-lineages, EU2-A and EU2-B. Specific mutations characterize each European lineage and geographic location seem to have shaped their phylogenetic structure. By investigating the spatial spread in Europe, we were able to show that Italy acted mainly as donor of USUV to neighbouring countries. At a national level, we identified two geographical clusters mainly circulating in Northern and North-western Italy, spreading both northward and southward. Our analyses provide important information on the spatial and evolutionary dynamics of USUTU virus that can help to improve surveillance plans and control strategies for this virus of increasing concern for human health.

Identification of a zoonotic genotype 3 hepatitis E subtype in wildlife in north-eastern Italy.

Hepatitis E virus (HEV) is an emerging zoonosis caused by a positive RNA single stranded virus of the Hepeviridae family. In developed countries, pigs and wild boars are the main reservoir for zoonotic genotypes 3 and 4. In spring 2017, for the first time HEV was detected in wild boars captured in the Regional Park of the Euganean Hills, in north-eastern Italy. Phylogenetic analysis of two complete viral genomes and seven partial ORF1 and ORF2 sequences of HEV viruses, selected from twelve positive animals, showed that the viruses grouped together within genotype 3 but clustered separately from previously identified subtypes, thus suggesting the identification of a novel genotype 3 subtype. The phylogenetic analysis of nine partial ORF2 sequences showed the closest similarity with wild boar/human viruses identified in central-northern Italy in 2012. The circulation of HEVs in this area, characterized by a vast man-made environment, an overpopulation of wild boars and >150 swine farms, should be considered in a public health perspective. Further investigations at the wild/domestic species and human interface are therefore necessary to gain a deeper understanding of HEV dynamics.

Integration of genetic and epidemiological data to infer H5N8 HPAI virus transmission dynamics during the 2016-2017 epidemic in Italy.

Between October 2016 and December 2017, several European Countries had been involved in a massive Highly Pathogenic Avian Influenza (HPAI) epidemic sustained by H5N8 subtype virus. Starting on December 2016, also Italy was affected by H5N8 HPAI virus, with cases occurring in two epidemic waves: the first between December 2016 and May 2017, and the second in July-December 2017. Eighty-three outbreaks were recorded in poultry, 67 of which (80.72%) occurring in the second wave. A total of 14 cases were reported in wild birds. Epidemiological information and genetic analyses were conjointly used to get insight on the spread dynamics. Analyses indicated multiple introductions from wild birds to the poultry sector in the first epidemic wave, and noteworthy lateral spread from October 2017 in a limited geographical area with high poultry densities. Turkeys, layers and backyards were the mainly affected types of poultry production. Two genetic sub-groups were detected in the second wave in non-overlapping geographical areas, leading to speculate on the involvement of different wild bird populations. The integration of epidemiological data and genetic analyses allowed to unravel the transmission dynamics of H5N8 virus in Italy, and could be exploited to timely support in implementing tailored control measures.

Modelling the species jump: towards assessing the risk of human infection from novel avian influenzas.

The scientific understanding of the driving factors behind zoonotic and pandemic influenzas is hampered by complex interactions between viruses, animal hosts and humans. This complexity makes identifying influenza viruses of high zoonotic or pandemic risk, before they emerge from animal populations, extremely difficult and uncertain. As a first step towards assessing zoonotic risk of influenza, we demonstrate a risk assessment framework to assess the relative likelihood of influenza A viruses, circulating in animal populations, making the species jump into humans. The intention is that such a risk assessment framework could assist decision-makers to compare multiple influenza viruses for zoonotic potential and hence to develop appropriate strain-specific control measures. It also provides a first step towards showing proof of principle for an eventual pandemic risk model. We show that the spatial and temporal epidemiology is as important in assessing the risk of an influenza A species jump as understanding the innate molecular capability of the virus. We also demonstrate data deficiencies that need to be addressed in order to consistently combine both epidemiological and molecular virology data into a risk assessment framework.

Modulation of IgE response and cytokine production in Peyer's patches and draining lymph nodes in sensitized mice made tolerant by oral dust mite administration.

Such allergic diseases as rhinitis and asthma are IgE-mediated type I reactions and are controlled primarily by Th2 cells. One of the major dust mites, Dermatophagoides pteronyssinus (Dp), is considered to cause allergic reactions. Oral tolerance, largely used to modulate immune response, opens the possibility of modulating Th2 allergic responses. We observed downmodulation of total and specific IgE antibody levels as well as the number of specific IgE-secreting cells with Dp feeding in previously sensitized mice. Analysis of the cytokine profile in mucosal lymphoid tissues in the protocol revealed altered patterns of interferon-gamma (IFN-gamma), interleukin-5 (IL-5), and transforming growth factor-beta (TGF-beta) secretion in Dp-fed animals. The results suggest that both the Th and B cell populations are modulated in mice made tolerant by oral Dp feeding. Understanding the mechanisms at the mucosal level that underlie oral tolerance can improve its use in allergy immunotherapy.

Oral tolerance induction in dermatophagoides pteronyssinus-sensitized mice induces inhibition of IgE response and upregulation of TGF-beta secretion.

Oral antigen administration induces peripheral tolerance in naive animals. Studies of oral tolerance induction in sensitized mice have clinical relevance as a strategy to modulate allergy. In this study, the A/Sn mice sensitized with extract of Dermatophagoides pteronyssinus (Dp) and submitted to oral Dp administration showed a marked decrease in IgE anti-Dp antibody production compared with sensitized phosphate-buffered saline (PBS)-fed mice. T cells from Dp-fed mice cocultured with spleen cells from PBS-fed mice were able to inhibit IgE anti-Dp antibody production and did not interfere in IgG1 antibody levels. The analysis of cytokine profile after Dp feeding showed a significant decrease in interleukin-4 (IL-4), IL-5, and IL-13 antigen-induced secretion levels by spleen cells, without shifting to IL-2 and interferon-gamma (IFN-gamma) production. Both transforming growth factor-beta (TGF-beta) baseline and TGF-beta antigen-stimulated levels were increased in Dp-fed mice. The effects of regulatory cytokines on anti-Dp IgE antibody production were investigated in vitro. The addition of recombinant TGF-beta (rTGF-beta) to spleen cell cultures stimulated by Dp inhibited IgE antibody secretion in both mouse groups. Neutralizing antibodies to IL-4, but not anti-TGF-beta, induced a marked inhibition of IgE production. Therefore, a negative modulatory effect on IgE response by inhibition of the axis Th2 was observed in sensitized Dp-fed mice, possibly mediated by induction of regulatory cytokines.

Paraproteinaemias and platelet aggregation: role of whole blood aggregometry.

Whole blood and optical platelet aggregation were measured in normals and in patients with paraproteinaemias; extent of aggregation was correlated with paraprotein concentrations in patients and in normals after addition of different doses of paraproteins; threshold aggregating concentrations of several agonists were also determined in whole blood and in PRP from both groups of subjects. The results indicate that patients with macromolecular monoclonal component bear a "hyperaggregable" state which can be probably ascribed also to plasma hyperviscosity and which is better detected with the impedance aggregometer.

Significance of CA 72.4 serum levels in gastrointestinal diseases.

In order to evaluate the usefulness of Ca 72.4 tumor associated antigen assay in gastrointestinal diseases, we have studied 751 patients suffering from benign (376) and neoplastic (375) digestive diseases and 305 normal controls. The cut-off point was fixed at 6 U/ml. The Ca 72.4 assay, with the proposed method, provides additional information only in gastric cancers; the positivity of the marker in gastric neoplasms is 38.4% and the specificity vs gastric ulcers and atrophic gastritis is 99%. In six patients with gastric cancer, the Ca 72.4 is the only positive test. The most striking observation to be made from the current study is a no good sensitivity of the marker for gastrointestinal cancers (29.6% vs 35.7 and 37.6% for CEA and Ca 19-9 respectively), but rather the excellent specificity of the Ca 72.4 immunoassay with respect to being gastrointestinal diseases (98.7%), vs values of specificity for CEA and Ca 19-9 of 94 and 92%. In conclusion, the high specificity of this marker for gastrointestinal neoplasms may be very interesting in follow-up studies. In fact, an elevation of serum levels of Ca 72.4 should always be taken seriously.

IgA response in serum and gut secretion in sensitized mice fed with the dust mite Dermatophagoides pteronyssinus extract.

Induced oral tolerance to mucosal-exposed antigens in immunized animals is of particular interest for the development of immunotherapeutic approaches to human allergic diseases. This is a unique feature of mucosal surfaces which represent the main contact interface with the external environment. However, the influence of oral tolerance on specific and natural polyreactive IgA antibodies, the major defense mechanism of the mucosa, is unknown. We have shown that oral administration of an extract of the dust mite Dermatophagoides pteronyssinus (Dp) to primed mice caused down-regulation of IgE responses and an increase in tumor growth factor-beta secretion. In the present study, we observed that primed inbred female A/Sn mice (8 to 10 weeks old) fed by gavage a total weight of 1.0-mg Dp extract on the 6th, 7th and 8th days post-immunization presented normal secretion of IL-4 and IL-10 in gut-associated lymphoid tissue and a decreased production of interferon gamma induced by Dp in the draining lymph nodes (13,340 +/- 3,519 vs 29,280 +/- 2,971 pg/ml). Mice fed the Dp extract also showed higher levels of serum anti-Dp IgA antibodies and an increase of IgA-secreting cells in mesenteric lymph nodes (N = 10), reflecting an increase in total fecal IgA antibodies (N = 10). The levels of secretory anti-Dp IgA antibodies increased after re-immunization regardless of Dp extract feeding. Oral tolerance did not interfere with serum or secretory IgA antibody reactivity related to self and non-self antigens. These results suggest that induction of oral tolerance to a Dp extract in sensitized mice triggered different regulatory mechanisms which inhibited the IgE response and stimulated systemic and secretory IgA responses, preserving the natural polyreactive IgA antibody production.

[Tag 72: a new tumor-associated antigen identified by a monoclonal antibody]. / Tag 72: un nuovo antigene tumore associato riconosciuto da un anticorpo monoclonale.

In order to evaluate the usefulness of Tag 72--tumor associated antigen assay--in gastroenterology, we have studied with Ca 72-4 radioimmunoassay (Centocor) 551 patients suffering benign (233) and neoplastic (318) gastrointestinal diseases and 205 normal controls. The cut-off point was fixed at 6 U/ml. Only in gastric cancers, the Tag 72 assay, with the proposed method, provide additional information in this pathology (sensitivity 30%, specificity 98.7%). The most striking observation to be made from the current study is a poor sensitivity of the test for gastrointestinal cancers, but rather the excellent specificity of the Ca 72-4 IRMA with respect to benign gastrointestinal diseases. The sensitivity of Ca 72-4 assay, vs Ca 19-9 and CEA, for the same diseases, is less, but specificity is better.

Macroamylasemia in a man from Bangladesh. A case report.

A 30-year-old man from Bangladesh was admitted to the hospital because of abdominal pain. Elevated amylase values (both pancreatic and non-pancreatic fractions) indicated a diagnosis of acute pancreatitis although all tests conducted to confirm this were negative. Amylase isoenzyme electrophoresis disclosed an immunocomplex made up of a salivary amylase molecule with an IgA that increased total and pancreatic fractions. A diagnosis of macroamylasemia was made. Although this is considered to be a benign condition, it is generally identified only after a long series of tests which could be avoided by the use of simple amylase isoenzyme electrophoresis.

Concomitant Infection with Leishmania donovani and L. major in Single Ulcers of Cutaneous Leishmaniasis Patients from Sudan.

In Sudan human leishmaniasis occurs in different clinical forms, that is, visceral (VL), cutaneous (CL), mucocutaneous (ML), and post-kala-azar dermal leishmaniasis (PKDL). Clinical samples from 69 Sudanese patients with different clinical manifestations were subjected to a PCR targeting the cytochrome oxidase II (COII) gene for Leishmania species identification. Mixed infections were suspected due to multiple overlapping peaks presented in some sequences of the COII amplicons. Cloning these amplicons and alignment of sequences from randomly selected clones confirmed the presence of two different Leishmania species, L. donovani and L. major, in three out of five CL patients. Findings were further confirmed by cloning the ITS gene. Regarding other samples no significant genetic variations were found in patients with VL (62 patients), PKDL (one patient), or ML (one patient). The sequences clustered in a single homogeneous group within L. donovani genetic group, with the exception of one sequence clustering with L. infantum genetic group. Findings of this study open discussion on the synergetic/antagonistic interaction between divergent Leishmania species both in mammalian and vector hosts, their clinical implications with respect to parasite fitness and response to treatment, and the route of transmission with respect to vector distribution and or adaptation.

Phylogenetic analysis of rabies viruses from Burkina Faso, 2007.

Genetic characterization of 32 canine rabies viruses circulating in Burkina Faso in 2007 identified two clades both belonging to the Africa 2 lineage. Sequence homology data suggest that transboundary spread is the most likely means of introduction, highlighting an evolving epidemiological situation.

Emergence of a new genetic lineage of Newcastle disease virus in West and Central Africa--implications for diagnosis and control.

Newcastle disease (ND) is an OIE listed disease caused by virulent avian paramyxovirus type 1 (APMV-1) strains, which affect many species of birds and may cause severe economic losses in the poultry sector. The disease has been officially and unofficially reported in many African countries and still remains the main poultry disease in commercial and rural chickens of Africa. Unfortunately, virological and epidemiological information concerning ND strains circulating in the Western and Central regions of Africa is extremely scarce. In the present study, sequence analysis, pathotyping and detailed genetic characterization of virulent ND strains detected in rural poultry in West and Central Africa revealed the circulation of a new genetic lineage, distinguishable from the lineages described in the Eastern and Southern parts of the continent. Several mismatches were observed in the segment of the matrix gene targeted by the primers and probe designed for the molecular detection of APMV-1, which were responsible for the false negative results in the diagnostic test conducted. Furthermore, deduced amino acid sequences of the two major antigens eliciting a protective immune response (F and HN glycoprotein) revealed protein similarities <90% if compared to some common vaccine strains. Distinct mutations located in the neutralizing epitopes were revealed, indicating the need for detailed assessment of the efficacy of the current vaccines and vaccination practices in Africa. The present investigation provides important information on the epidemiology, diagnosis and control of NDV in Africa and highlights the importance of supporting surveillance in developing countries for transboundary animal diseases.