First record of the Indo-Pacific species Iphione muricata Savigny in Lamarck, 1818 (Polychaeta: Iphionidae) from the Mediterranean Sea, Israel

The Indo-Pacific scaleworm Iphione muricata was observed and caught in the Mediterranean Sea along the coast of Israel. Morphological and molecular diagnostic characters of the species are discussed. This is the first record of this alien species in the Mediterranean Sea, and its previous reports in the Suez Canal suggest its introduction via Lessepsian migration

Stimulated wave of polarization in spin chains

Stimulated wave of polarization, triggered by a flip of a single spin, presents a simple model of quantum amplification. Previously, it has been found that such wave can be excited in a 1D Ising chain with nearest-neighbor interactions, irradiated by a weak resonant transverse field. Here we explore models with more realistic Hamiltonians, in particular, with natural dipole-dipole interactions. Results of simulations for 1D spin chains and rings with up to nine spins are presented.Comment: 15 pages, 5 figure

Raman investigation of corrosion products on Roman copper-based artefacts

This paper illustrates a case study related to the characterisation of corrosion products present on recently excavated artefacts. The archaeological findings, from the Rakafot 54 site (Beer-Sheva, Israel), consist of 23 coins and a pendant, all dating back to the Roman period. Raman spectroscopy was used to identify the corrosion products that compose the patina covering the objects. To facilitate and support their identification, spectra were then processed using principal components analysis. This chemometric technique allowed the identification of two main compounds, classified as atacamite and clinoatacamite, which formed the main components of the patinas. The results of this investigation can help in assessing the conservation state of artefacts and defining the correct restoration strategy

Non-invasive characterization of ancient Cu-based coins using Raman spectroscopy

Characterization of archaeological finds is a challenging case study for researchers, as the need of non-invasive measurements strongly affects the investigation strategies. Moreover, it is almost not possible to follow a fixed protocol, because the measurement conditions should be tailored to the samples under study. This paper presents a preliminary characterization of bronze coins coming from an archaeological site located in the south of Israel. The superficial corrosion layers have been analysed by means of Raman spectroscopy in order to investigate their composition and assess the conservation state of the finds. Reference samples of known composition have also been used to help peaks identification in the Raman spectra. Results coming from this study can help in defining the correct conservation strategies for the artefacts

Raman and micromorphological characterization of carbonates in plaster-like materials from the Natufian site of Eynan (Ain Mallaha), Israel

The archaeological site of Eynan, located by the spring of Ain Mallaha and on the shores of Lake Hula in the Upper Jordan Valley, Israel, existed for several millennia at the end of the Pleistocene. During the Natufian culture of the Levantine Epipalaeolithic, the site was one of the largest known occupations in the Levant for some millennia (ca. 14,300 - 11,900 cal BP). Remains of Natufian architecture were found, together with evidence of early experimenting with pyrotechnology for the creation of lime plaster. Several features were identified during the excavations as assumed lime plaster installations. Samples investigated by micromorphology methods under the polarizing microscope revealed that while all were composed of calcium carbonate, and some indeed represent anthropogenic burnt lime products, others reflected the results of post-depositional or contemporaneous natural processes rather than technological products. The study of the samples at a molecular level through Raman spectroscopy enables a new methodology for the quick distinction between the features observed by micromorphology

Persistent global power fluctuations near a dynamic transition in electroconvection

This is a study of the global fluctuations in power dissipation and light transmission through a liquid crystal just above the onset of electroconvection. The source of the fluctuations is found to be the creation and annihilation of defects. They are spatially uncorrelated and yet temporally correlated. The temporal correlation is seen to persist for extremely long times. There seems to be an especially close relation between defect creation/annihilat ion in electroconvection and thermal plumes in Rayleigh-B\'enard convection

Direct Measurement of the System-Environment Coupling as a Tool For Understanding Decoherence and Dynamical Decoupling

Decoherence is a major obstacle to any practical implementation of quantum information processing. One of the leading strategies to reduce decoherence is dynamical decoupling --- the use of an external field to average out the effect of the environment. The decoherence rate under any control field can be calculated if the spectrum of the coupling to the environment is known. We present a direct measurement of the bath coupling spectrum in an ensemble of optically trapped ultracold atoms, by applying a spectrally narrow-band control field. The measured spectrum follows a Lorentzian shape at low frequencies, but exhibits non-monotonic features at higher frequencies due to the oscillatory motion of the atoms in the trap. These features agree with our analytical models and numerical Monte-Carlo simulations of the collisional bath. From the inferred bath-coupling spectrum, we predict the performance of well-known dynamical decoupling sequences: CPMG, UDD and CDD. We then apply these sequences in experiment and compare the results to predictions, finding good agreement in the weak-coupling limit. Thus, our work establishes experimentally the validity of the overlap integral formalism, and is an important step towards the implementation of an optimal dynamical decoupling sequence for a given measured bath spectrum.Comment: 9 pages, 6 figure

The Supercooling of a Nematic Liquid Crystal

We investigate the supercooling of a nematic liquid crystal using fluctuating non-linear hydrodynamic equations. The Martin-Siggia-Rose formalism is used to calculate renormalized transport coefficients to one-loop order. Similar theories for isotropic liquids have shown substantial increases of the viscosities as the liquid is supercooled or compressed due to feedback from the density fluctuations which are freezing. We find similar results here for the longitudinal and various shear viscosities of the nematic. However, the two viscosities associated with the nematic director motion do not grow in any dramatic way; i.e.\ there is no apparent freezing of the director modes within this hydrodynamic formalism. Instead a glassy state of the nematic may arise from a ``random anisotropy" coupling of the director to the frozen density.Comment: Late

Dynamics and Selection of Giant Spirals in Rayleigh-Benard Convection

For Rayleigh-Benard convection of a fluid with Prandtl number \sigma \approx 1, we report experimental and theoretical results on a pattern selection mechanism for cell-filling, giant, rotating spirals. We show that the pattern selection in a certain limit can be explained quantitatively by a phase-diffusion mechanism. This mechanism for pattern selection is very different from that for spirals in excitable media