518 research outputs found
Immune function and parasite resistance in male and polymorphic female Coenagrion puella
Background:
Colour polymorphisms are widespread and one of the prime examples is the colour
polymorphism in female coenagrionid damselflies: one female morph resembles the male colour
(andromorph) while one, or more, female morphs are described as typically female (gynomorph).
However, the selective pressures leading to the evolution and maintenance of this polymorphism
are not clear. Here, based on the hypothesis that coloration and especially black patterning can be
related to resistance against pathogens, we investigated the differences in immune function and
parasite resistance between the different female morphs and males.
Results:
Our studies of immune function revealed no differences in immune function between the
female morphs but between the sexes in adult damselflies. In an experimental infection females
infected shortly after emergence showed a higher resistance against a fungal pathogen than males,
however female morphs did not differ in resistance. In a field sample of adult damselflies we did not
find differences in infection rates with watermites and gregarines.
Conclusion:
With respect to resistance and immune function 'andromorph' blue females of
Coenagrion puella do not resemble the males. Therefore the colour polymorphism in coenagrionid
damselflies is unlikely to be maintained by differences in immunity
High-power broadband laser source tunable from 3.0 um to 4.4 um based on a femtosecond Yb:fiber oscillator
We describe a tunable broadband mid-infrared laser source based on
difference-frequency mixing of a 100 MHz femtosecond Yb:fiber laser oscillator
and a Raman-shifted soliton generated with the same laser. The resulting light
is tunable over 3.0 um to 4.4 um, with a FWHM bandwidth of 170 nm and maximum
average output power up to 125 mW. The noise and coherence properties of this
source are also investigated and described.Comment: To appear in Optics Letter
Optical Solitary Waves in the Higher Order Nonlinear Schrodinger Equation
We study solitary wave solutions of the higher order nonlinear Schrodinger
equation for the propagation of short light pulses in an optical fiber. Using a
scaling transformation we reduce the equation to a two-parameter canonical
form. Solitary wave (1-soliton) solutions exist provided easily met inequality
constraints on the parameters in the equation are satisfied. Conditions for the
existence of N-soliton solutions (N>1) are determined; when these conditions
are met the equation becomes the modified KdV equation. A proper subset of
these conditions meet the Painleve plausibility conditions for integrability.Comment: REVTeX, 4 pages, no figures. To appear in Phys. Rev. Let
Conservation Laws in Higher-Order Nonlinear Optical Effects
Conservation laws of the nonlinear Schr\"{o}dinger equation are studied in
the presence of higher-order nonlinear optical effects including the
third-order dispersion and the self-steepening. In a context of group theory,
we derive a general expression for infinitely many conserved currents and
charges of the coupled higher-order nonlinear Schr\"{o}dinger equation. The
first few currents and charges are also presented explicitly. Due to the
higher-order effects, conservation laws of the nonlinear Schr\"{o}dinger
equation are violated in general. The differences between the types of the
conserved currents for the Hirota and the Sasa-Satsuma equations imply that the
higher-order terms determine the inherent types of conserved quantities for
each integrable cases of the higher-order nonlinear Schr\"{o}dinger equation
Homodyne detection for atmosphere channels
We give a systematic theoretical description of homodyne detection in the
case where both the signal and the local oscillator pass through the turbulent
atmosphere. Imperfect knowledge of the local-oscillator amplitude is
effectively included in a noisy density operator, leading to postprocessing
noise. Alternatively, we propose a technique with monitored transmission
coefficient of the atmosphere, which is free of postprocessing noise.Comment: 9 pages, 5 figure
Toward Global Quantum Communication: Beam Wandering Preserves Nonclassicality
Tap-proof long-distance quantum communication requires a deep understanding
of the strong losses in transmission channels. Here we provide a rigorous
treatment of the effects of beam wandering, one of the leading disturbances in
atmospheric channels, on the quantum properties of light. From first principles
we derive the probability distribution of the beam transmissivity, with the aim
to completely characterize the quantum state of light. It turns out that beam
wandering may preserve nonclassical effects, such as entanglement, quadrature
and photon number squeezing, much better than a standard attenuating channel of
the same losses.Comment: published versio
Sviluppo di tecniche di simulazione eterogenea funzionale e numerica applicate all’ingegneria di sistemi aeronautici
Questo studio illustra l’impiego del ‘Model Based Systems Engineering’ (MBSE), in cui strumenti di modellazione funzionale si integrano con modelli numerici, da tempo impiegati in progettazione, per la realizzazione di sistemi complessi. E’ analizzato un sistema antighiaccio aeronautico, sviluppato nell’ambito del progetto ‘CRYSTAL’. L’obiettivo è stato raggiunto collegando il gestore di requisiti IBM DOORS®, IBM RHAPSODY®, che opera in ambiente SysML, e SIMULINK® o DYMOLA®. L’interoperabilità è stata garantita dallo standard di connessione Functional Mock–up Interface (FMI), che ha permesso di validare il processo realizzando la cosiddetta ‘simulazione eterogenea’ di modelli funzionali e numerici integrati
Heat-Shock Protein 90 Controls the Expression of Cell-Cycle Genes by Stabilizing Metazoan-Specific Host-Cell Factor HCFC1
Molecular chaperones such as heat-shock proteins (HSPs) help in protein folding. Their function in the cytosol has been well studied. Notably, chaperones are also present in the nucleus, a compartment where proteins enter after completing de novo folding in the cytosol, and this raises an important question about chaperone function in the nucleus. We performed a systematic analysis of the nuclear pool of heat-shock protein 90. Three orthogonal and independent analyses led us to the core functional interactome of HSP90. Computational and biochemical analyses identify host cell factor C1 (HCFC1) as a transcriptional regulator that depends on HSP90 for its stability. HSP90 was required to maintain the expression of HCFC1-targeted cell-cycle genes. The regulatory nexus between HSP90 and the HCFC1 module identified in this study sheds light on the relevance of chaperones in the transcription of cell-cycle genes. Our study also suggests a therapeutic avenue of combining chaperone and transcription inhibitors for cancer treatment
Multisoliton solutions and integrability aspects of coupled nonlinear Schrodinger equations
Using Painleve singularity structure analysis, we show that coupled
higher-order nonlinear Schrodinger (CHNLS) equations admit Painleve property.
Using the results of Painleve analysis, we succeed in Hirota bilinearizing the
CHNLS equations, one soliton and two soliton solutions are explictly obtained.
Lax pairs are explictly constructed.Comment: Eight pages and six figures. Physical Review E (to be appear
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