Experimental study of a non-gaussian Fabry-Perot resonator to depress mirror thermal noise for gravitational waves detectors

This thesis is a study of a new kind of Fabry-Perot long-baseline optical resonator proposed for gravitational waves interferometric detectors: the Mesa beam profile Fabry-Perot cavity. A detailed experimental work has been performed on a prototype built in the LIGO laboratories of the California Institute of Technology. The aim of this experiment is to explore all of the main properties of such an optical cavity including: the reliability of its control; beam distortions due to surface imperfections and misalignments; the efficiency of the coupling to a gaussian input beam. The advantage to use a non-spherical optics resonator consists in the possibility to significantly reduce test masses thermal noise which is expected to be the fundamental limit for advanced gravitational waves interferometric detectors, such as Advanced LIGO. It is possible to generate a flat-top, wider laser beam probe of such a detector just reshaping the profile of its mirrors. The characteristic ``Mexican hat' mirror profile has been designed to support a flat-top beam, the so-called Mesa beam. Three test mirrors have been manufactured by the LMA laboratory (Lyon, France) in order to study the behavior of this new family of laser beams in our Fabry Perot prototype. A brief introduction about the problem of estimating mirror thermal noises, their physical sources and how to treat them formally, using, for example, Levin's direct approach is presented. After that, this thesis deals with all the physical characteristic of finite size optical resonators and the related experimental issues like the lock acquisition techniques. A overview of the Mesa beam design and related theoretical issues is included. The second part of this thesis treats all the experimental issues of our experiment: a Fabry-Perot, folded, suspended optical resonator 7 meters long conceived to store Nd:YAG laser light with optics sizes scaled down from the Advanced LIGO baseline parameters. It is placed inside a vacuum pipe and the spacing between the mirrors is determined by three INVAR rods. A cavity finesse of about 100 is achieved by tuning the reflectivity of the input (flat) mirror. The other two mirrors, the folding mirror, and the end mirror, which can be either a spherical or a Mexican hat mirror, have high reflectivity coatings. During this year of operations, the cavity was always operated in air. The stability of the mechanics has been tested with a spherical mirror, 8 meters radius of curvature. The input and output optics layout has been developed to match and study this preliminary cavity configuration. The control electronics, necessary to keep the cavity locked on a resonance, has been made and assembled so that it is possible to use either a side-lock feedback on the laser frequency or the cavity length dithering technique. A high voltage driver circuit has been designed and assembled to drive the mirror piezo actuators. A preliminary study of the cavity beam profile was performed for the spherical optics configuration: several beam profile samples of the fundamental mode and higher order modes were compared to the theoretical predictions. The last part of this work was the characterization of the cavity behavior with the first Mexican hat mirror. Since spherical symmetry is lost for such a resonator, the resonant beam depends on the particular mirrors and input beam alignment. Beam profiles recorded were compared with realistic simulations based on the Fast Fourier Transform implementation of the beam propagation and using the actual Mexican hat mirror map. Finally, the first Mesa beam fundamental mode was acquired and analyzed

Coherent control of quantum transport: modulation-enhanced phase detection and band spectroscopy

Amplitude modulation of a tilted optical lattice can be used to steer the quantum transport of matter wave packets in a very flexible way. This allows the experimental study of the phase sensitivity in a multimode interferometer based on delocalization-enhanced Bloch oscillations and to probe the band structure modified by a constant force.Comment: 8 pages, 3 figures, Submitted to EPJ Special Topics for the special issue on "Novel Quantum Phases and Mesoscopic Physics in Quantum Gases

Optically loaded Strontium lattice clock with a single multi-wavelength reference cavity

We report on the realization of a new compact strontium optical clock using a 2-D magneto-optical-trap (2D-MOT) as cold atomic source and a multi-wavelength cavity as the frequency stabilization system. All needed optical frequencies are stabilized to a zero-thermal expansion high-finesse optical resonator and can be operated without frequency adjustments for weeks. We present the complete characterization of the apparatus. Optical control of the atomic source allows us to perform low-noise clock operation without atomic signal normalization. Long- and short-term stability tests of the clock have been performed for the 88 Sr bosonic isotope by means of interleaved clock operation. Finally, we present the first preliminary accuracy budget of the system

Acquired ptosis associated with oculomotor and contralateral facial nerve synkinesis: the first reported case

Evidence of oculomotor nerve (ON) synkinesis is a common occurrence following both acquired and congenital III nerve palsy. It is generally accepted that aberrant regeneration is the likely aetiology of synkinesis in acquired III nerve palsy, following intracranial aneurysm, trauma, compressive neoplasms, cavernous sinus thrombosis and basilar meningitis

Septic Shock by Gram-Negative Infections: Role of Outer Membrane Proteins

The magnitude of septic shock as a clinical problem is often understated. Despite advances in our ability to diagnose and treat infectious diseases, severe sepsis leading to shock due to gram-negative infections remains one of the leading causes of mortality worldwide. Septic shock develops because of a disregulation in the host response, and the mechanisms initially recruited to fight infection produce life-threatening tissue damage and death. Recent research has witnessed a significant increase in our understanding of host-pathogen interactions, particularly in the area of innate immunity and the molecular recognition of gram-positive and gram-negative bacteria. Important new mediators of sepsis and novel mechanisms of host-cell toxicity have been identified and, together with clinical trials targeting pathways considered central to sepsis pathogenesis, provide new insight into the molecular and cellular basis of sepsis for the formulation of new strategies of intervention. Research on septic shock pathogenesis by gram-negative bacteria is mainly focused on the understanding of the molecular and cellular role played by lipopolysaccharide (LPS). Strong experimental evidence and clinical observations suggest that the release of proinflammatory cytokine mediators by LPS-responsive cells (mainly macrophages, endothelial cells and neutrophils) in response to toxic products sets in motion the genetic and physiologic program that manifests as shock. The best characterized of these toxic components is LPS, which is considered as a paradigm for other less well-characterized toxic microbial molecules. The immune protection stimulated by highly purified LPS in animals does not resolve the symptomatology of septic shock, while LPS mixed to outer membrane proteins shows a better protective activity. Several studies evidence the major role played by outer membrane proteins in the molecular interaction between the host cell and the gram-negative bacteria. Endotoxin-associated proteins consist of a complex of several major proteins that are intimately associated with the LPS. Very little is known about release of non-LPS gramnegative outer membrane components such as OMPs in sepsis. Among the OMPs, porins have been shown to play an important role in pathogenesis of bacterial infections. Porins were pyrogenic in rabbits and elicited a localized reaction when used as the sensiting and eliciting agent. Porins were also shown to kill D-galactosamine sensitized LPS-responsive and LPS-unresponsive mice. Treatment of Human Umbilical Vein Endothelial Cells: (HUVEC) with porins increased the transmigration of different leukocyte populations, inparticular of neutrophils. Porins by several gram-negative bacteria induce cytokine release by human leukocytes as well as enhancement of cytokine gene expression. Also, other components of the bacterial envelope are important in the induction and pathogenesis of septic shock such as bacterial lipoproteins (LP). As anti-LPS therapies does not seem to improve by the addition of proteins from the outer membrane or small fragments of these proteins, a great alternative to existing strategies will involve the blockage of signal transduction pathways, cytokine and inflammatory mechanisms

Review of a viral peptide nanosystem for intracellular delivery

The internalization of bioactive molecules is one of the most critical problems to overcome in theranostics. In order to improve pharmacokinetic and pharmacodynamic proper- ties, synthetic transporters are widely investigated. A new nanotechnological transporter, gH625, is based on a viral peptide sequence derived from the herpes simplex virus type 1 glycoprotein H (gH) that has proved to be a useful delivery vehicle, due to its intrinsic properties of inducing membrane perturbation. The peptide functionalization with several kinds of nanoparticles like quantum dots, dendrimers, and liposomes could be of particular interest in biomedical applica- tions to improve drug release within cells, to increase site-specific action, and eventually to reduce related cytotoxicity. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. (DOI: 10.1117/1.JNP.7.071599