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This article provides a physical solution to cosmic inflation, the onset of the radiation epoch and the reheating epoch. It does not require dark energy thanks to a zero cosmological constant. Cosmological inflation is a mathematical solution considered necessary for the coherence of cosmological models. There are several versions of it, but there is currently no physical basis to explain it. We show that the existence of negative heavy masses (but always positive inert masses) makes it possible to explain it and also makes it possible to justify many other phenomena. Experiments are underway to test the hypothesis of negative heavy masses. The first results should be obtained within 1 or 2 years. In this solution, inflation would occur at the onset of the gravitational interaction much earlier than in the commonly accepted chronology. Gravitation would give rise to a negative pressure primordial fluid verifying the inflation conditions known as "slow roll". It would lead to regularity in matter density and temperature of the CMB. The structures of filaments, walls and large cosmic voids (and even superclusters) could be explained as a consequence of the influence of this matter of negative gravitational mass., Cet article fournit une solution physique à l’inflation cosmologique, à l’apparition de la période de radiation et à la période de réchauffement. Elle ne nécessite pas d’énergie noire grâce à une constante cosmologique nulle. L’inflation cosmologique est une solution mathématique considérée comme nécessaire à la cohérence des modèles cosmologiques. Il en existe plusieurs versions, mais aucun fondement physique n’est actuellement capable de l’expliquer. Nous montrons que l’existence de masses pesantes négatives (mais toujours de masses inertes positives) permet de l’expliquer et permet aussi de justifier de nombreux autres phénomènes. Des expériences sont en cours pour tester l’hypothèse de masses pesantes négatives. Les premiers résultats devraient être obtenus d’ici 1 ou 2 ans. Dans cette solution, l’inflation se déroulerait à l’apparition de l’interaction gravitationnelle bien plus tôt que dans la chronologie couramment admise. La gravitation donnerait naissance à un fluide primordial de pression négative vérifiant les conditions d’inflation dite de « roulement lent ». Elle conduirait jusqu’à la régularité en densité de matière et en température du CMB. Les structures de filaments, murs et de grands vides cosmiques (voire même les superamas) pourraient s’expliquer comme conséquence de l’influence de cette matière de masse gravitationnelle négative.

Parabacteroides distasonis (Pdis) is the type species for the new Parabacteroides genus, and a gut commensal of the Bacteroidetes phylum. Emerging reports (primarily based on reference strain/ATCC-8503) concerningly propose that long-known opportunistic pathogen Pdis is a probiotic. We posit there is an urgent need to characterize the pathogenicity of Pdis strain-strain variability. Unfortunately, no methods/insights exist to classify Bacteroidetes for this purpose. Herein, we developed a virulence gene-based classification system for Pdis and Bacteroidetes to facilitate pathogenic-vs-probiotic characterization. We used DNA in silico methods to develop a system based on the virulence (lipopolysaccharide/bacterial wall) ‘rfbA O-antigen-synthesis gene’. We then performed phylogenetic analysis of rfbA from fourteen Pdis complete genomes (21 genes), other Parabacteroides, Bacteroidetes, and Enterobacteriaceae; and proposed a PCR-based Restriction-Fragment Length Polymorphism method. Cluster analysis revealed that Pdis can be classified into four lineages (based on gene gaps/insertions) which we designated rfbA-Types I, II, III, and IV. In context, we found 14 additional rfbA-types (I–XVIII) interspersed with numerous Bacteroidetes and pathogenic Enterobacteriaceae forming three major “rfbA-superclusters.” For laboratory rfbA-Typing implementation, we developed a PCR-primer strategy to amplify Pdis rfbA genes (100%-specificity) to conduct MboII-RFLP and sub-classify Pdis. In-silico primers for other Bacteroidetes are proposed/discussed. Comparative analysis of lipopolysaccharide/lipid-A gene lpxK confirmed rfbA as highly discriminant. In conclusion, rfbA-Typing classifies Bacteroidetes/Pdis into unique clusters/superclusters given rfbA copy/sequence variability. Analysis revealed that most pathogenic Pdis strains are single-copy rfbA-Type I . The relevance of the rfbA strain variability in disease might depend on their hypothetical modulatory interactions with other O-antigens/lipopolysaccharides and TLR4 lipopolysaccharide-receptors in human/animal cells.

The thermal history of melts leads to three liquid states above the melting temperatures Tm containing clusters—bound colloids with two opposite values of enthalpy +Δεlg × ΔHm and −Δεlg × ΔHm and zero. All colloid bonds disconnect at Tn+ &gt, Tm and give rise in congruent materials, through a first-order transition at TLL = Tn+, forming a homogeneous liquid, containing tiny superatoms, built by short-range order. In non-congruent materials, (Tn+) and (TLL) are separated, Tn+ being the temperature of a second order and TLL the temperature of a first-order phase transition. (Tn+) and (TLL) are predicted from the knowledge of solidus and liquidus temperatures using non-classical homogenous nucleation. The first-order transition at TLL gives rise by cooling to a new liquid state containing colloids. Each colloid is a superatom, melted by homogeneous disintegration of nuclei instead of surface melting, and with a Gibbs free energy equal to that of a liquid droplet containing the same magic atom number. Internal and external bond number of colloids increases at Tn+ or from Tn+ to Tg. These liquid enthalpies reveal the natural presence of colloid–colloid bonding and antibonding in glass-forming melts. The Mpemba effect and its inverse exist in all melts and is due to the presence of these three liquid states.

The Formation of Catastrophically Cooling Outflows in Star-forming Regions via Non-equilibrium Radiative Cooling Multiwavelength surveys of star-forming regions suggest the presence of catastrophically cooling outflows, also sometimes accompanied by warm outflows and hot bubbles. Mechanical feedback from super star clusters in starburst regions can produce cooling galactic-scale outflows, but starburst-driven outflows predicted by the adiabatic fluid models cannot lead to very strong cooling seen in several star-forming galaxies such as M82 and NGC 2366. We therefore simulate starburst-driven outflows using time-dependent non-equilibrium radiative cooling functions of the MAIHEM non-equilibrium package in the framework of the hydrodynamics code FLASH in order to determine the existence domains of strongly radiative cooling, so called catastrophic cooling, in the parameter space of the gas metallicity, outflow mass-loading, outflow kinetic heating efficiency, and ambient density. Although the gas metallicity has a major role in cooling, radiative cooling is significantly enhanced by increasing mass-loading and decreasing kinetic heating efficiency. Our simulations indicate hot bubbles may appear even with both the adiabatic and substantially radiative cooling outflows. Our results demonstrate the significance of non-equilibrium radiative cooling for star-forming regions, where coolants could be responsible for the build-up of cold molecular hydrogen (H2) clumps that can trigger the formation of new stars as gravitational collapse occurs once the H2 clump’s mass exceeds the Jeans critical mass. Poster presented at Star Formation: From Clouds to Discs (dias.ie/cloudstodiscs), Dublin Institute for Advanced Studies, Malahide, Ireland, 18-21 October 2021, {"references":["Chevalier and Clegg Natur, 317, 44 (1985)","Danehkar, Oey, and Gray ApJ, accepted, arXiv:2106.10854 (2021)","Ferland, Chatzikos, Guzmán et al. RMxAA, 53, 385 (2017)","Fryxell, Olson, Ricker et al. ApJS, 131, 273 (2000)","Gray, Oey, Silich Scannapieco et al. ApJ, 887, 161 (2019)","Heckman, Armus, and Miley ApJS, 74, 833 (1990)","Leitherer, Ekström, Meynet et al. ApJS, 212, 14 (2014)","Oey and Massey ApJ, 452, 210 (1995)","Oey, Herrera, Silich et al. ApJL, 849, L1 (2017)","Silich, Tenorio-Tagle, and Rodríguez-González ApJ, 610, 226 (2004)","Smith, Westmoquette, Gallagher et al. MNRAS, 370, 513 (2006)","Turner, Consiglio, Beck et al. ApJ, 846, 73 (2017)","Weaver, McCray, Castor et al. ApJ, 218, 377 (1977)"]}

This article provides a physical solution to cosmic inflation, the onset of the radiation epoch and the reheating epoch. It does not require dark energy thanks to a zero cosmological constant. Cosmological inflation is a mathematical solution considered necessary for the coherence of cosmological models. There are several versions of it, but there is currently no physical basis to explain it. We show that the existence of negative heavy masses (but always positive inert masses) makes it possible to explain it and also makes it possible to justify many other phenomena. Experiments are underway to test the hypothesis of negative heavy masses. The first results should be obtained within 1 or 2 years. In this solution, inflation would occur at the onset of the gravitational interaction much earlier than in the commonly accepted chronology. Gravitation would give rise to a negative pressure primordial fluid verifying the inflation conditions known as "slow roll". It would lead to regularity in matter density and temperature of the CMB. The structures of filaments, walls and large cosmic voids (and even superclusters) could be explained as a consequence of the influence of this matter of negative gravitational mass., Cet article fournit une solution physique à l’inflation cosmologique, à l’apparition de la période de radiation et à la période de réchauffement. Elle ne nécessite pas d’énergie noire grâce à une constante cosmologique nulle. L’inflation cosmologique est une solution mathématique considérée comme nécessaire à la cohérence des modèles cosmologiques. Il en existe plusieurs versions, mais aucun fondement physique n’est actuellement capable de l’expliquer. Nous montrons que l’existence de masses pesantes négatives (mais toujours de masses inertes positives) permet de l’expliquer et permet aussi de justifier de nombreux autres phénomènes. Des expériences sont en cours pour tester l’hypothèse de masses pesantes négatives. Les premiers résultats devraient être obtenus d’ici 1 ou 2 ans. Dans cette solution, l’inflation se déroulerait à l’apparition de l’interaction gravitationnelle bien plus tôt que dans la chronologie couramment admise. La gravitation donnerait naissance à un fluide primordial de pression négative vérifiant les conditions d’inflation dite de « roulement lent ». Elle conduirait jusqu’à la régularité en densité de matière et en température du CMB. Les structures de filaments, murs et de grands vides cosmiques (voire même les superamas) pourraient s’expliquer comme conséquence de l’influence de cette matière de masse gravitationnelle négative.

En este trabajo de tesis realizamos un estudio estadístico de la dinámica y la distribución espacial de las mayores regiones del Universo desprovistas de galaxias brillantes, denominadas vacíos, utilizando datos observacionales y simulaciones numéricas. Analizamos la dinámica centrándonos en la dinámica global y su relación con el entorno en gran escala, encontrando que se trata de subdensidades que se desplazan con un amplio rango de velocidades, con una clara dependencia con el entorno y un valor medio de aproximadamente 350 km s$^{−1} $, contribuyendo a los grandes flujos de materia del Universo. Asimismo, realizamos un análisis de la distribución espacial y su evolución a través de la función de correlación de dos puntos, encontrando evidencia de la formación de asociaciones de vacíos, las cuales dependen del entorno y se mantienen invariante en las diferentes etapas el Universo.

The article analyses the current Сanadian system of agricultural innovation clusters. It examines the regional and sectoral clusters. Special attention is paid to the new national project to create innovative superclusters in Canada.

The new revolution in materials science is being driven by our ability to manipulate matter at the molecular level to create structures with novel functions and properties. The aim of this paper is to explore new strategies to obtain plasmonic metal nanostructures through the combination of a top down method, that is electron beam lithography, and a bottom up technique, that is the chemical electroless deposition. This technique allows a tight control over the shape and size of bi- and three-dimensional metal patterns at the nano scale. The resulting nanostructures can be used as constituents of Surface Enhanced Raman Spectroscopy (SERS) substrates, where the electromagnetic field is strongly amplified. Our results indicate that, in electroless growth, high quality metal nanostructures with sizes below 50 nm may be easily obtained. These findings were explained within the framework of a diffusion limited aggregation (DLA) model, that is a simulation model that makes it possible to decipher, at an atomic level, the rules governing the evolution of the growth front; moreover, we give a description of the physical mechanisms of growth at a basic level. In the discussion, we show how these findings can be utilized to fabricate dimers of silver nanospheres where the size and shape of those spheres is controlled with extreme precision and can be used for very large area SERS substrates and nano-optics, for single molecule detection.

A crucial diagnostic of the \Lambda CDM cosmological model is the integrated Sachs-Wolfe (ISW) effect of large-scale structure on the cosmic microwave background (CMB). The ISW imprint of superstructures of size \sim100\;h^{-1} Mpc at redshift $z\sim0.5$ has been detected with $>4\sigma$ significance, however it has been noted that the signal is much larger than expected. We revisit the calculation using linear theory predictions in \Lambda CDM cosmology for the number density of superstructures and their radial density profile, and take possible selection effects into account. While our expected signal is larger than previous estimates, it is still inconsistent by $>3\sigma$ with the observation. If the observed signal is indeed due to the ISW effect then huge, extremely underdense voids are far more common in the observed universe than predicted by \Lambda CDM., Comment: 3 figures. v3: minor additions for clearer explanations, conclusions unchanged. Version to be published in JCAP

The Modified Catalog of Galaxy Clusters and Groups (Panko & Flin 2006, PF), covering an area of 5000 square degrees in the southern sky, was used as the input for the search of galaxy superclusters. Only the estimated redshifts could be used, since the PF catalog is a 2D catalog, with the calibration correlating the redshift of galaxy clusters with the magnitude of the tenth brightest cluster galaxy. Only galaxy clusters containing more than 50 galaxies were considered, and the FoF method was applied. The nearest neighbour distances for 1711 input clusters were calculated and analyzed, and 20 isolated clusters were found with the nearest neighbour at a distance greater than 68 h-1Mpc. A distance of 24 h-1 Mpc between clusters was selected for the supercluster search, and 49 superclusters containing from 4 to 9 galaxy clusters were detected. Calculations for each supercluster include: its inferred center, RA, Dec, zest, the maximum distance between supercluster members and the estimated supercluster shapes. A typical size of superclusters identified here is about 55 h-1 Mpc, and they appear mainly as elongated pancakes, with a weak correlation between the axes c/a and b/a, without a strong dependence on multiplicity.

One of the main problems of observational cosmology is to determine the range in which a reliable measurement of galaxy correlations is possible. This corresponds to determine the shape of the correlation function, its possible evolution with redshift and the size and amplitude of large scale structures. Different selection effects, inevitably entering in any observation, introduce important constraints in the measurement of correlations. In the context of galaxy redshift surveys selection effects can be caused by observational techniques and strategies and by implicit assumptions used in the data analysis. Generally all these effects are taken into account by using pair-counting algorithms to measure two-point correlations. We review these methods stressing that they are based on the a-priori assumption that galaxy distribution is spatially homogeneous inside a given sample. We show that, when this assumption is not satisfied by the data, results of the correlation analysis are affected by finite size effects.In order to quantify these effects, we introduce a new method based on the computation of the gradient of galaxy counts along tiny cylinders. We show, by using artificial homogeneous and inhomogeneous point distributions, that this method is to identify redshift dependent selection effects and to disentangle them from the presence of large scale density fluctuations. We then apply this new method to several redshift catalogs and we find evidences that galaxy distribution, in those samples where selection effects are small enough, is characterized by power-law correlations with exponent $\gamma=0.9$ up to $20$ Mpc/h followed by a change of slope that, in the range [20,100] Mpc/h, corresponds to a power-law exponent $\gamma=0.25$. Whether a crossover to spatial unformity occurs at $\sim 100$ Mpc/h cannot be clarified by the present data., Comment: 35 pages, Journal of Cosmology and Astroparticle Physics in the press

A few experiments have already detected the presence of icosahedral superclusters in undercooled liquids, confirming a possible homogeneous nucleation of such entities as suggested by Franck. These superclusters survive in melts above the crystal melting temperature Tm because all their surface atoms have the same fusion heat as their core atoms and are melted by homogeneous nucleation of liquid in their core, depending on overheating time and temperature. In complete contrast to current ideas, a long time is necessary to melt them and to attain the thermodynamic equilibrium above Tm. They act as heterogeneous growth nuclei of crystallized phase at a temperature Tc of the undercooled melt when they are not melted. They contribute to the reduction of the critical barrier, which becomes smaller than that of crystals containing the same atom number n. The undercooling rate is always limited, even in a liquid at thermodynamic equilibrium, because the homogeneous nucleation of 13-atom superclusters reduces the energy barrier, and increases Tc above the homogeneous nucleation temperature equal to Tm/3 in liquid elements. After weak superheating, the most stable superclusters containing n = 13, 55, 147, 309 and 561 atoms survive or melt and determine Tc during undercooling, which depends on n and on the sample volume. The experimental nucleation temperatures Tc of 32 liquid elements and the melting temperatures of superclusters are predicted without any adjustable parameter using a sample volume varying by nearly 18 orders of magnitude. The classical Gibbs free energy change is used, adding an enthalpy saving related to the Laplace pressure change associated with supercluster formation, which is quantified and strongly weakened for n = 13 and 55., Comment: 29 pages,17 figures. In this new version, some figure captions and comments have been improved. The author contribution to this field is underlined. Now, the references contain the paper titles

We present a search for spatial and redshift correlations in a 2 Angstrom, resolution spectroscopic survey of the Ly alpha forest at 2.15

We present a search for spatial and redshift correlations in a 2 Angstrom, resolution spectroscopic survey of the Ly alpha forest at 2.15

We present a specific prescription for the calculation of cosmological power spectra, exploited here at two-loop order in perturbation theory (PT), based on the multi-point propagator expansion. In this approach power spectra are constructed from the regularized expressions of the propagators that reproduce both the resummed behavior in the high-k limit and the standard PT results at low-k. With the help of N-body simulations, we show that such a construction gives robust and accurate predictions for both the density power spectrum and the correlation function at percent-level in the weakly non-linear regime. We then present an algorithm that allows accelerated evaluations of all the required diagrams by reducing the computational tasks to one-dimensional integrals. This is achieved by means of pre-computed kernel sets defined for appropriately chosen fiducial models. The computational time for two-loop results is then reduced from a few minutes, with the direct method, to a few seconds with the fast one. The robustness and applicability of this method are tested against the power spectrum cosmic emulator from which a wide variety of cosmological models can be explored. The fortran program with which direct and fast calculations of power spectra can be done, RegPT, is publicly released as part of this paper., 28 pages, 15 figures

The formalism to compute the geometrical and topological one-point statistics of mildly non-Gaussian 2D and 3D cosmological fields is developed. Leveraging the isotropy of the target statistics, the Gram-Charlier expansion is reformulated with rotation invariant variables. This formulation allows us to track the geometrical statistics of the cosmic field to all orders. It then allows us to connect the one point statistics of the critical sets to the growth factor through perturbation theory, which predicts the redshift evolution of higher order cumulants. In particular, the cosmic non-linear evolution of the skeleton's length, together with the statistics of extrema and Euler characteristic are investigated in turn. In 2D, the corresponding differential densities are analytic as a function of the excursion set threshold and the shape parameter. In 3D, the Euler characteristics and the field isosurface area are also analytic to all orders in the expansion. Numerical integrations are performed and simple fits are provided whenever closed form expressions are not available. These statistics are compared to estimates from N-body simulations and are shown to match well the cosmic evolution up to root mean square of the density field of ~0.2. In 3D, gravitational perturbation theory is implemented to predict the cosmic evolution of all the relevant Gram-Charlier coefficients for universes with scale invariant matter distribution. The one point statistics of critical sets could be used to constrain primordial non-Gaussianities and the dark energy equation of state on upcoming cosmic surveys; this is illustrated on idealized experiments., 41 pages, 13 figures, submitted to Phys Rev D

Tesis (Doctor en Astronomía)--Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física, 2011. En esta tesis se presenta un nuevo método para determinar la probabilidad de encontrar eventos extremos en la distribución de materia oscura fría. En nuestra aproximación usamos un conjunto de simulaciones de N-Cuerpos para encontrar estructuras extremas, concluyendo que la frecuencia de estos eventos es bien descripta por la distribución de Gumbel. Esto permite enfrentar la dificultad de la falta de muestras estadísticamente confiables de estos eventos, anticipando la probabilidad de encontrarlos en una dada distribución, sin la necesidad de hacer suposiciones sobre la forma detallada de la distribución subyacente. La aplicación de dicha técnica a los supercúmulos de galaxias permite analizar la validez del modelo ΛCDM. En este trabajo también se llevó a cabo un estudio detallado sobre la dependencia del clustering de las galaxias con las superestructuras. La comparación de dicho clustering de galaxias, diferenciando entre las galaxias situadas dentro y fuera de superestructuras, brinda valiosa información sobre la evolución conjunta de las estructuras más masivas presentes actualmente en el Universo y las galaxias. Mediante este análisis, se encuentra que la estructura interna de los grupos y cúmulos es un indicador sensible de las diferentes historias de agregación jerárquica dentro y fuera de superestructuras.

I investigate the influence of a non-zero cosmological constant on the evolution of anisotropy in overdensities that grow by gravitational collapse. The claim that a positive value of LAMBDA might produce stronger asphericities is considered by following the collapse of homogeneous spheroids imbedded in Friedman-Lemaitre backgrounds. It is shown that, although the calculations indeed show this effect, it is small for the values of LAMBDA allowed by the classical cosmological tests. When we do not limit ourselves by constraints arising from the choice of an initial fluctuation spectrum, structures in an open universe (OMEGA0) = 0.1, lamda0 = 0), including the peculiar velocity structure, can be reproduced in a flat Lemaitre universe (OMEGA0 = 0.1, lambda0 = 0.9) for a large part of their evolution. From initial conditions that are not too extreme, these two world models are both able to produce strong anisotropies that easily persist for a Hubble time. This stability of flattening is the only aspect in which these two models differ significantly from the Einstein-de Sitter model. Taking into account the crudeness of the model, together with the fact that observed large-scale structures are not isolated, we conclude that use of this aspect of the dynamics of structure formation is not a promising method of placing tighter constraints on the value of LAMBDA.

Cosmological backreaction suggests a link between structure formation and the expansion history of the Universe. In order to quantitatively examine this connection, we dynamically investigate a volume partition of the Universe into over-- and underdense regions. This allows us to trace structure formation using the volume fraction of the overdense regions $\lambda_{\CM}$ as its characterizing parameter. Employing results from cosmological perturbation theory and extrapolating the leading mode into the nonlinear regime, we construct a three--parameter model for the effective cosmic expansion history, involving $\lambda_{\CM_{0}}$, the matter density $\Omega_{m}^{\CD_{0}}$, and the Hubble rate $H_{\CD_{0}}$ of today's Universe. Taking standard values for $\Omega_{m}^{\CD_{0}}$ and $H_{\CD_{0}}$ as well as a reasonable value for $\lambda_{\CM_{0}}$, that we derive from $N$--body simulations, we determine the corresponding amounts of backreaction and spatial curvature. We find that the obtained values that are sufficient to generate today's structure also lead to a $\Lambda$CDM--like behavior of the scale factor, parametrized by the same parameters $\Omega_{m}^{\CD_{0}}$ and $H_{\CD_{0}}$, but without a cosmological constant. However, the temporal behavior of $\lambda_{\CM}$ does not faithfully reproduce the structure formation history. Surprisingly, however, the model matches with structure formation with the assumption of a low matter content, $\Omega_{m}^{\CD_{0}}\approx3\%$, a result that hints to a different interpretation of part of the backreaction effect as kinematical Dark Matter. (truncated), Comment: 25 pages, 10 figures, includes calculation of luminosity distances, matches published version in Phys. Rev. D

Tesis (Doctor en Astronomía)--Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física, 2009. En este trabajo de tesis se llevó a cabo un estudio estadístico completo acerca de las regiones subdensas (vacíos) en el Universo. Para tal fin se analizaron las características espaciales y dinámicas de regiones subdensas en simulaciones numéricas cosmológicas, pobladas con galaxias semianalíticas, y catálogos observacionales de galaxias. Se examinaron las propiedades de las galaxias en paredes de vacíos en catálogos de galaxias (SDSS y 2dFGRS). Los resultados sugieren una dependencia con el medio a gran escala, posiblemente vinculada al material que se acumula en las paredes de las regiones subdensas como consecuencia de la expansión. Se analizó el patrón de distorsiones en el espacio de redshift de la función de correlación cruzada entre vacíos y galaxias, obteniéndose estimas de la velocidad de expansión de las regiones vacías. por María Laura Ceccarelli.

Galaxy-galaxy or galaxy-quasar lensing can provide important information on the mass distribution in the Universe. It consists of correlating the lensing signal (either shear or magnification) of a background galaxy/quasar sample with the number density of a foreground galaxy sample. However, the foreground galaxy density is inevitably altered by the magnification bias due to the mass between the foreground and the observer, leading to a correction to the observed galaxy-lensing signal. The aim of this paper is to quantify this correction. The single most important determining factor is the foreground redshift z: the correction is small if the foreground galaxies are at low redshifts but can become non-negligible for sufficiently high redshifts. For instance, we find that for the multipole l=1000, the correction is above 1%*(5s-2)/b for z, 10 pages, 7 figures; v2: minor revisions, as accepted for publication in Physical Review D

The contribution of cosmological perturbations to the time drift of the cosmological redshift is derived. It is shown that the dominant correction arises from the local acceleration of both the emitter and the observer. The amplitude of this effect is estimated to be of the order of 1% of the drift signal at z=2-4, but can easily be lowered down to 0.1% by using many absorption lines and quasars., 6 pages, 2 figures. Fig. 1 modified. Accepted for publication in PRD

Monthly Notices of the Royal Astronomical Society, 352 (3), ISSN:0035-8711, ISSN:1365-2966, ISSN:1365-8711

We present a search for spatial and redshift correlations in a 2 Angstrom, resolution spectroscopic survey of the Ly alpha forest at 2.15