650 research outputs found
Arabidopsis thaliana growth more than defense affects Myzus persicae populations
Aphids and other herbivorous insects are able to travel between plants in their environment. While plants cannot directly choose their consumers, they may stop or mitigate the harmful effects of herbivory using secondary metabolites. A salicylic acid (SA) pathway facilitates defense from biotrophic fungi and some necrotrophic pathogens, while a jasmonic acid (JA) pathway is associated with defense from other necrotrophic pathogens and chewing insects. We investigated the effect of deficiency in SA or JA in Arabidopsis thaliana on plant growth and on herbivory by green peach aphids (Myzus persicae). Three ascensions of A. thaliana were placed in two blocks with three aphids on each individual. The genotypes consisted of a SA-deficient ascension (Sid2), a JA-deficient ascension (Lox2), and a wild type (Col). Wild-type A. thaliana showed significantly greater growth relative to the other ascensions, suggesting better performance, as well as dramatically higher aphid count. Aphid count showed a significant positive correlation with plant growth, suggesting that M. persicae is attracted to signs of growth in A. thaliana, or reproduces more on growing plants. It appears that wild-type plants showed greater growth throughout the experiment, and were thus targeted by the highly responsive M. persicae. This behaviour may be exploited for agricultural purposes; herbivorous insects may be diverted to fast-growing trap crops lacking agricultural value in order to protect primary crops.Faculty Sponsor: Dr. Chad Harve
Influence of radiation exposure on the properties of dielectric layers based on anodic aluminum oxide
Devices that are used in the aerospace industry must operate in extreme conditions, so it is important to understand how the properties of materials change under the influence of radiation and low temperatures. Anodic aluminum oxide, due to its mechanical and dielectric properties, is widely used in electronic devices with a high degree of integration. Radiation exposure can lead to degradation of the electrophysical parameters of dielectric films and can also change their chemical composition. The methods for studying the effect of radiation exposure on the dielectric properties of films are shown in this article. The research has been carried out and the results of the influence of α-particles on the dielectric properties of a porous film of anodic aluminum oxide during the influence of low temperature are presented.Devices that are used in the aerospace industry must operate in extreme conditions, so it is important to understand how the properties of materials change under the influence of radiation and low temperatures. Anodic aluminum oxide, due to its mechanical and dielectric properties, is widely used in electronic devices with a high degree of integration. Radiation exposure can lead to degradation of the electrophysical parameters of dielectric films and can also change their chemical composition. The methods for studying the effect of radiation exposure on the dielectric properties of films are shown in this article. The research has been carried out and the results of the influence of α-particles on the dielectric properties of a porous film of anodic aluminum oxide during the influence of low temperature are presented
The Geometry of D=11 Killing Spinors
We propose a way to classify all supersymmetric configurations of D=11
supergravity using the G-structures defined by the Killing spinors. We show
that the most general bosonic geometries admitting a Killing spinor have at
least a local SU(5) or an (Spin(7)\ltimes R^8)x R structure, depending on
whether the Killing vector constructed from the Killing spinor is timelike or
null, respectively. In the former case we determine what kind of local SU(5)
structure is present and show that almost all of the form of the geometry is
determined by the structure. We also deduce what further conditions must be
imposed in order that the equations of motion are satisfied. We illustrate the
formalism with some known solutions and also present some new solutions
including a rotating generalisation of the resolved membrane solutions and
generalisations of the recently constructed D=11 Godel solution.Comment: 36 pages. Typos corrected and discussion on G-structures improved.
Final version to appear in JHE
Outcome with lenalidomide plus dexamethasone followed by early autologous stem cell transplantation in patients with newly diagnosed multiple myeloma on the ECOG-ACRIN E4A03 randomized clinical trial: long-term follow-up
In Eastern Cooperative Oncology Group-ACRIN E4A03, on completion of four cycles of therapy, newly diagnosed multiple myeloma patients had the option of proceeding to autologous peripheral blood stem cell transplant (ASCT) or continuing on their assigned therapy lenalidomide plus low-dose dexamethasone (Ld) or lenalidomide plus high-dose dexamethasone (LD). This landmark analysis compared the outcome of 431 patients surviving their first four cycles of therapy pursuing early ASCT to those continuing on their assigned therapy. Survival distributions were estimated using the Kaplan–Meier method and compared with log-rank test. Ninety patients (21%) opted for early ASCT. The 1-, 2-, 3-, 4- an
Invasive Streptococcus pyogenes Infections in <3-Month-Old Infants in France: Clinical and Laboratory Features.
Few data are available on invasive group A Streptococcus (GAS) infections (IGASIs) in infants. We described initial clinical and laboratory features and outcomes of <3-month-old infants hospitalized for an IGASI between 2007 and 2016 in France. Patients were identified from the French National Reference Centre for streptococci. IGASI was defined by the isolation of GAS from blood cultures or from other usually sterile sites. Data collection was performed by assessing the patients' hospitalization reports. Twenty-six patients (15 males; 57.7%) were included. Among 19 cases with available data, 14 (73.7%) were household contacts of a GAS infection, reaching 8/9 (88.9%) in neonates. The diagnoses were bacteremia (n = 18; 69.2%), pleural effusion or pneumonia (n = 6; 23.1%), meningitis with brain abscess (n = 1; 3.8%), and septic arthritis (n = 1; 3.8%). Fever (n = 10; 38.5%), hemodynamic disorders (n = 11; 42.3%), respiratory disorders (n = 7; 26.9%), thrombocytopenia (n = 7; 26.9%), and neutropenia (n = 5; 19.2%) were frequently observed. The main emm-genotype was emm-1 (n = 8; 30.8%). Thirteen (50.0%) infants have been admitted to the intensive care unit, and two (7.7%) died. Respiratory disorders, high C-reactive protein level, and the need for transfusion were significantly associated with severity. IGASI remains uncommon in <3-month-old children but leads to a high morbidity. Whether an antibiotic prophylaxis for contact neonates of a patient with GAS infection decreases the risk of infection remains to be determined
Bulk vs. Boundary Dynamics in Anti-de Sitter Spacetime
We investigate the details of the bulk-boundary correspondence in Lorentzian
signature anti-de Sitter space. Operators in the boundary theory couple to
sources identified with the boundary values of non-normalizable bulk modes.
Such modes do not fluctuate and provide classical backgrounds on which bulk
excitations propagate. Normalizable modes in the bulk arise as a set of
saddlepoints of the action for a fixed boundary condition. They fluctuate and
describe the Hilbert space of physical states. We provide an explicit, complete
set of both types of modes for free scalar fields in global and Poincar\'e
coordinates. For \ads{3}, the normalizable and non-normalizable modes
originate in the possible representations of the isometry group
\SL_L\times\SL_R for a field of given mass. We discuss the group properties
of mode solutions in both global and Poincar\'e coordinates and their relation
to different expansions of operators on the cylinder and on the plane. Finally,
we discuss the extent to which the boundary theory is a useful description of
the bulk spacetime.Comment: Standard LaTeX, 28 pages, 2 postscript figures. v2: References added.
Substantial revision in section 3 of treatment of global modes;
non-normalizable modes have arbitrary time dependence. Revised discussion of
low-mass modes and puzzle raised re: coupling of the dual boundary operators.
v3: unwanted paragraph removed. v4: Sec. 5.2 correcte
Spectrum of Chiral Operators in Strongly Coupled Gauge Theories
We analyze the large spectrum of chiral primary operators of three
dimensional fixed points of the renormalization group. Using the space-time
picture of the fixed points and the correspondence between anti-de Sitter
compactifications and conformal field theories we are able to extract the
dimensions of operators in short superconformal multiplets. We write down some
of these operators in terms of short distance theories flowing to these
non-trivial fixed points in the infrared.Comment: harvmac, 16 pages, one acknowledgement adde
All solutions of the localization equations for N=2 quantum black hole entropy
We find the most general bosonic solution to the localization equations
describing the contributions to the quantum entropy of supersymmetric black
holes in four-dimensional N=2 supergravity coupled to n_v vector multiplets.
This requires the analysis of the BPS equations of the corresponding off-shell
supergravity (including fluctuations of the auxiliary fields) with AdS2 \times
S2 attractor boundary conditions. Our work completes and extends the results of
arXiv:1012.0265 that were obtained for the vector multiplet sector, to include
the fluctuations of all the fields of the off-shell supergravity. We find that,
when the auxiliary SU(2) gauge field strength vanishes, the most general
supersymmetric configuration preserving four supercharges is labelled by n_v+1
real parameters corresponding to the excitations of the conformal mode of the
graviton and the scalars of the n_v vector multiplets. In the general case, the
localization manifold is labelled by an additional SU(2) triplet of one-forms
and a scalar function.Comment: 27 page
Intersections of quadrics, moment-angle manifolds, and Hamiltonian-minimal Lagrangian embeddings
We study the topology of Hamiltonian-minimal Lagrangian submanifolds N in C^m
constructed from intersections of real quadrics in a work of the first author.
This construction is linked via an embedding criterion to the well-known
Delzant construction of Hamiltonian toric manifolds. We establish the following
topological properties of N: every N embeds as a submanifold in the
corresponding moment-angle manifold Z, and every N is the total space of two
different fibrations, one over the torus T^{m-n} with fibre a real moment-angle
manifold R, and another over a quotient of R by a finite group with fibre a
torus. These properties are used to produce new examples of Hamiltonian-minimal
Lagrangian submanifolds with quite complicated topology.Comment: 14 pages, published version (minor changes
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