Linear response of entanglement entropy from holography

For time-independent excited states in conformal field theories, the entanglement entropy of small subsystems satisfies a `first law'-like relation, in which the change in entanglement is proportional to the energy within the entangling region. Such a law holds for time-dependent scenarios as long as the state is perturbatively close to the vacuum, but is not expected otherwise. In this paper we use holography to investigate the spread of entanglement entropy for unitary evolutions of special physical interest, the so-called global quenches. We model these using AdS-Vaidya geometries. We find that the first law of entanglement is replaced by a linear response relation, in which the energy density takes the role of the source and is integrated against a time-dependent kernel with compact support. For adiabatic quenches the standard first law is recovered, while for rapid quenches the linear response includes an extra term that encodes the process of thermalization. This extra term has properties that resemble a time-dependent `relative entropy'. We propose that this quantity serves as a useful order parameter to characterize far-from-equilibrium excited states. We illustrate our findings with concrete examples, including generic power-law and periodically driven quenches.Comment: 31+3 pages, 8 figures; v2: typos fixed and references added; v3: claims on universality sharpened (section 2.1), version to appear in JHE

Models of landscape evolution of the Spanish Sistema Central Range: Morphotectonics implications

[Abstract] The characteristic morphostructure of the Spanish Central System corresponds to that of an ancient leveled massif, reactivated during the Tertiary Age by tectonic impulses related to the Alpine Orogeny; that is to say, it forms a block organized mountainous massif, or a «block mountain» o Although noumerous genetic models about the formation ofthe morphostructure ofthese mountains have been proposed, only three ofthem could be considered to be fundamental: the first one proposes a «polycyclic» or «hemicyclic» denudational and tectonic-uplift sequence; but, at the same time, it clearly shows a «stair-like» physiognomy shape (Piedmont bendlanch orPiedmonttreppen); the second one describes a «cyclic» or «bicyclic» model which could be in conection with a «block mountain» physiognomy; the last model suggests a denudational and tectonic-uplift interaction sequence, with an increase of the tectonic activity and an «etchplain» process development during the Tertiary periodo According to the three basic models pointed to aboye, two main possibilities can be taken into account to find out the tectonic implications in the evolution of the Spanish Central System landscape: the former implies that the tectonic movements and the denudational processes are alternative events in time; the latter implies that the tectonic and the denudational effects have a succesive and continous occurrenceo So, the most interesting thing would be to conclude something related to this issue; as has been stated, it would be necesssary to make a global interpretation of the tectonic setting and, as a consequence, of the reactivated landscapes formation of the Meseta Region in Central Spain. Therefore, it would be essential to consider the following aspects: the behaviour of the tectonic movements during the reactivation, the geographical and chronological distribution ofthe tectonic impulses, the origin ofthe stresses and their way of transmission, and the precise control of the present and the near present day tectonic movements in order to define the uplift and subsidence rates

Transverse momentum dependence of the angular distribution of the Drell-Yan process

We calculate the transverse momentum Q_{\perp} dependence of the helicity structure functions for the hadroproduction of a massive pair of leptons with pair invariant mass Q. These structure functions determine the angular distribution of the leptons in the pair rest frame. Unphysical behavior in the region Q_{\perp} --> 0 is seen in the results of calculations done at fixed-order in QCD perturbation theory. We use current conservation to demonstrate that the unphysical inverse-power and \ln(Q/Q_{\perp}) logarithmic divergences in three of the four independent helicity structure functions share the same origin as the divergent terms in fixed-order calculations of the angular-integrated cross section. We show that the resummation of these divergences to all orders in the strong coupling strength \alpha_s can be reduced to the solved problem of the resummation of the divergences in the angular-integrated cross section, resulting in well-behaved predictions in the small Q_{\perp} region. Among other results, we show the resummed part of the helicity structure functions preserves the Lam-Tung relation between the longitudinal and double spin-flip structure functions as a function of Q_{\perp} to all orders in \alpha_s.Comment: 18 pages, 4 figures; typos corrected, references updated, a few clarifications recommended by the referee. Paper accepted for publication in Physical Review

Sea level height, sea surface temperature, and tuna yields in the Panama bight during El Niño

Between 1988 and 1998, annual tuna landings at Buenaventura (Colombian Pacific) are correlated with the sea surface temperature in the central Equatorial Pacific (<i>r</i>=0.78, <i>p</i>&lt;0.05) and the sea level height at Buenaventura (<i>r</i>=0.76, <i>p</i>&lt;0.05) and Balboa (Panama) (<i>r</i>=0.79, <i>p</i>&lt;0.05). Seasonal oceanic upwelling is forced by the Panama wind jet, which may favour oceanic fisheries such as tuna. Here we first apply a bivariate correlation method (Pyper and Peterman, 1994) and then a multivariate approach (principal components analysis or PCA) to investigate the relationships of these environmental variables with landings. With the first method, we find that landing is best correlated with the sea surface temperature in the Ni&#241;o 3 region, whereas the other relationships are less clear. In contrast, with PCA we find that PC1 explains 90.6% of the total variance and suggests that sea surface temperature plays a major role in determining tuna availability in the area (especially during El Ni&#241;o events). Since PC2 is mainly correlated with sea level height at Balboa but only represents 6.8% of the total variance, we suggest that oceanic upwelling effects on tuna landings at Buenaventura are not significant at interannual scales

Callose deposition and symplastic connectivity are regulated prior to lateral root emergence.

Root growth is critical for the effective exploitation of the rhizosphere and productive plant growth. Our recent work(1) showed that root architecture was dependent upon the degree of symplastic connectivity between neighboring cells during the specification of lateral root primordia and was affected by genes regulating callose deposition at plasmodesmata (PD). Here we provide additional evidence that both symplastic connectivity and callose are also important during the later phase of lateral root development: emergence. Callose immunolocalization assays indicated that transient symplastic isolation of the primordium occur immediately prior to emergence through the overlaying tissues to produce the mature lateral root.(1) Here we could corroborate these results by analyzing the mobility of a symplastic tracer and the expression of PD genes in lateral roots and in response to auxins. Moreover, we show that altering callose deposition affects the number of emerged lateral roots suggesting that PD regulation is important for emergence

Controlled Irradiative Formation of Penitentes

Spike-shaped structures are produced by light-driven ablation in very different contexts. Penitentes 1-4 m high are common on Andean glaciers, where their formation changes glacier dynamics and hydrology. Laser ablation can produce cones 10-100 microns high with a variety of proposed applications in materials science. We report the first laboratory generation of centimeter-scale snow and ice penitentes. Systematically varying conditions allows identification of the essential parameters controlling the formation of ablation structures. We demonstrate that penitente initiation and coarsening requires cold temperatures, so that ablation leads to sublimation rather than melting. Once penitentes have formed, further growth of height can occur by melting. The penitentes intially appear as small structures (3 mm high) and grow by coarsening to 1-5 cm high. Our results are an important step towards understanding and controlling ablation morphologies.Comment: Accepted for publication in Physical Review Letter