2,119 research outputs found
A survey of cherry leaf roll virus in intensively managed grafted english (Persian) walnut trees in Italy
Blackline disease, caused by Cherry leaf roll virus (CLRV), is considered a serious threat limiting English walnut (Juglans regia) production in Italy and the EU if walnut species other than J. regia e.g. \u2018Paradox\u2019 hybrid (J. regia
7 J. hindsii), French hybrid (J. regia
7 J. major or J. regia
7 J. nigra) or northern California black walnut (J. hindsii) are used as the rootstock. The virus transmissibility by pollen as well as latent infections can result in the spread of CLRVcontaminated propagative material, which is a major means of the virus dispersal by human activities. In 2014 and 2015 to ascertain the presence and the distribution of blackline symptoms in commercial orchards and to provide a description of the symptomatology, visual inspections and double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) analyses were carried out on 1,684 walnut trees in four different intensively managed grafted English walnut orchards in northeast Italy (Veneto Region). Trees with clear blackline symptoms at the scion-rootstock junction, often associated with general decline of the plant, were found only in one commercial orchard in northeast Italy on trees older than ten years of cvs. \u2018Tulare\u2019 and \u2018Chandler\u2019, grafted onto \u2018Paradox\u2019 rootstock. To our knowledge this is the first report of CLRV (blackline) decline and death in a commercial walnut orchard in Italy
Naked Singularities as Particle Accelerators II
We generalize here our earlier results on particle acceleration by naked
singularities. We showed recently[1] that the naked singularities that form due
to gravitational collapse of massive stars provide a suitable environment where
particles could get accelerated and collide at arbitrarily high center of mass
energies. However, we focussed there only on the spherically symmetric
gravitational collapse models, which were also assumed to be self-similar. In
this paper, we broaden and generalize the result to all gravitational collapse
models leading to the formation of a naked singularity as final state of
collapse, evolving from a regular initial data, without making any prior
restrictive assumptions about the spacetime symmetries such as above. We show
that when the particles interact and collide near the Cauchy horizon, the
energy of collision in the center of mass frame will be arbitrarily high, thus
offering a window to the Planck scale physics. We also consider the issue of
various possible physical mechanisms of generation of such very high energy
particles from the vicinity of naked singularity. We then construct a model of
gravitational collapse to a timelike naked singularity to demonstrate the
working of these ideas, where the pressure is allowed to be negative but the
energy conditions are respected. We show that a finite amount of mass-energy
density has to be necessarily radiated away from the vicinity of the naked
singularity as the collapse evolves. Therefore the nature of naked
singularities, both at classical and quantum level could play an important role
in the process of particle acceleration, explaining the occurrence of highly
energetic outgoing particles in the vicinity of Cauchy horizon that participate
in extreme high energy collisions.Comment: 13 pages, 5 figures, Accepted for publication in Phys. Rev. D,
Reference and Acknowledgments adde
Free boundary problem for the role of planktonic cells in biofilm formation and development
The dynamics of biofilm lifecycle are deeply influenced by the surrounding
environment and the interactions between sessile and planktonic phenotypes.
Bacterial biofilms typically develop in three distinct stages: attachment of
cells to a surface, growth of cells into colonies, and detachment of cells from
the colony into the surrounding medium. The attachment of planktonic cells
plays a prominent role in the initial phase of biofilm lifecycle as it
initiates the colony formation. During the maturation stage, biofilms harbor
numerous microenvironments which lead to metabolic heterogeneity. Such
microniches provide conditions suitable for the growth of new species, which
are present in the bulk liquid as planktonic cells and can penetrate the porous
biofilm matrix. We present a 1D continuum model on the interaction of sessile
and planktonic phenotypes in biofilm lifestyle which considers both the initial
attachment and colonization phenomena. The model is formulated as a
hyperbolic-elliptic free boundary value problem with vanishing initial value.
Hyperbolic equations reproduce the transport and growth of sessile species,
while elliptic equations model the diffusion and conversion of planktonic cells
and dissolved substrates. The attachment is modelled as a continuous,
deterministic process which depends on the concentrations of the attaching
species. The growth of new species is modelled through a reaction term in the
hyperbolic equations which depends on the concentration of planktonic species
within the biofilm. Existence and uniqueness of solutions are discussed and
proved for the attachment regime. Finally, some numerical examples show that
the proposed model correctly reproduces the growth of new species within the
biofilm and overcomes the ecological restrictions characterizing the
Wanner-Gujer type models.Comment: 17 pages, 9 figures, preprint versio
Continuous two-step anaerobic digestion (TSAD) of organic market waste: rationalising process parameters
Experimental tests on continuous two-stage anaerobic digestion (TSAD) were conducted, to assess its energetic performance, using organic market waste as a substrate. The systems were tested to ascertain the effects of external stressors, which allow the separation into two different microorganism consortia, that is, hydrogen-producing bacteria and hydrogen-consuming bacteria, to be maintained. Two bioreactors were run in series under different operational conditions, including pH, mixing rate, and initial inoculum, and three different decreasing hydraulic retention times were considered, with a fixed ratio of 1:10 in volume between the first bioreactor (hydrogen) and the second one (methane). The performance of the whole system was assessed over > 140 days to monitor the stability of the process, in terms of the reduction of the volatile solids and the energy productivity for each step. Each tested condition was scored using two parameters: efficiency and efficacy. The first corresponds to the fraction of recovered energy of the available (η) and the second (ξ) was used to compare the energy produced by the TSAD with that of one-step anaerobic digestion. The efficiency resulted to be (24–32)%, while the efficacy proved to be around 1.20. The share of energy, under the form of hydrogen, compared to the total energy recovery, was in the (8–12) % range. Finally, the oscillation behaviour of the quasi-steady-state condition was analysed in terms of the Fano factor to establish the most stable conditions
Tracing dark energy history with gamma ray bursts
Observations of gamma-ray bursts up to are best suited to study the
possible evolution of the Universe equation of state at intermediate redshifts.
We apply the Combo-relation to a sample of 174 gamma ray bursts to investigate
possible evidence of evolving dark energy parameter . We first build a
gamma ray burst Hubble's diagram and then we estimate the set (,
) in the framework of flat and non-flat CDM
paradigm. We then get bounds over the CDM model, where is thought to
evolve with redshift, adopting two priors over the Hubble constant in tension
at -, i.e. km/s/Mpc and
km/s/Mpc. We show our new sample provides tighter constraints on
since at we see that agrees within 1 with the
standard value . The situation is the opposite at larger , where gamma
ray bursts better fix that seems to deviate from at -
and - level, depending on the redshift bins. In particular, we
investigate the evolution through a piecewise formulation over seven
redshift intervals. From our fitting procedure we show that at the
case cannot be fully excluded, indicating that dark energy's influence
is not negligible at larger . We confirm the Combo relation as a powerful
tool to investigate cosmological evolution of dark energy. Future space
missions will significantly enrich the gamma ray burst database even at smaller
redshifts, improving de facto the results discussed in this paper.Comment: 10 pages, 7 figures, ApJ submitte
Cannabidiol and oxygen-ozone combination induce cytotoxicity in human pancreatic ductal adenocarcinoma cell lines
Pancreatic cancer (PC) is related to lifestyle risks, chronic inflammation, and germline mutations in BRCA1/2, ATM, MLH1, TP53, or CDKN2A. Surgical resection and adjuvant chemotherapy are the main therapeutic strategies but are less effective in patients with high-grade tumors. Oxygen-ozone (O2/O3) therapy is an emerging alternative tool for the treatment of several clinical disorders. O2/O3 therapy has been found to ameliorate mechanisms promoting chronic pain and inflammation, including hypoxia, inflammatory mediators, and infection. The advantages of using cannabinoids have been evaluated in vitro and in vivo models of several human cancers. Regarding PDAC, activation of cannabinoid receptors was found to induce pancreatic cancer cell apoptosis without affecting the normal pancreas cells. In a murine model of PDAC, a combination of cannabidiol (CBD) and gemcitabine increased survival length by nearly three times. Herein, we evaluate the anticancer effect of CBD and O2/O3, alone or in combination, on two human PDAC cell lines, PANC-1 and MiaPaCa-2, examining expression profiles of 92 pancreatic adenocarcinoma associated genes, cytotoxicity, migration properties, and cell death. Finally, we assess the combination effects with gemcitabine and paclitaxel. Summarizing, for the first time the antitumoral effect of combined therapy with CBD and oxygen-ozone therapy in PDAC is evidenced
- …