Shear dispersion in the thermocline and the saline intrusion

Over the mid-Atlantic shelf of the North America, there is a pronounced shoreward intrusion of the saltier slope water along the seasonal thermocline, whose genesis remains unexplained. Taking note of the observed broad-band baroclinic motion, we postulate that it may propel the saline intrusion via the shear dispersion. Through an analytical model, we first examine the shear-induced isopycnal diffusivity ("shear diffusivity" for short) associated with the monochromatic forcing, which underscores its varied even anti-diffusive short-term behavior and the ineffectiveness of the internal tides in driving the shear dispersion. We then derive the spectral representation of the long-term "canonical" shear diffusivity, which is found to be the baroclinic power band-passed by a diffusivity window in the log-frequency space. Since the baroclinic power spectrum typically plateaus in the low-frequency band spanned by the diffusivity window, canonical shear diffusivity is simply 1/8 of this low-frequency plateau — independent of the uncertain diapycnal diffusivity. Applied to the mid-Atlantic shelf, this canonical shear diffusivity is about 20 m2 s−1, which is sufficient to account for the observed tracer dispersion or saline intrusion in the thermocline

Alimentary canal of the lesser house fly, Fannia canicularis (Linnaeus) (Diptera: Fanniidae)

The alimentary canal of Fannia canicularis was studied intensively for the first time, highlighting the description of morphological characteristics and providing detailed morphometric data. Two pairs of Malpighian tubules with considerably different length were found which has been rarely documented for Calyptratae flies before. Furthermore, stout cardia and sinewy crop of the samples were ob- served and supposed to be responsible for the energy needed to support the long- time swarming behavior of the species

How to Retain Consumers: A Trust-Commitment Model

Although studies on the determinants of consumers’ continuance intention in e-marketplaces have grown in recent years, the research is predominantly related to unidimensional trust and commitment. In this research, the authors focus on the distinct roles of different types of consumer trust and commitment on consumers’ continuance intention. Drawing upon organizational commitment and trust theories, we develop a continuance intention model that includes two types of trust and two types of commitments. We collected a sample of 287 online consumers to validate the theoretical model. Our data suggest that consumers’ trust and commitment positively affect their continuance intention. Our study also indicates that the psychological states underlying the commitments are different. Key findings and implications are discussed

Hahn echo and criticality in spin-chain systems

We establish a relation between Hahn spin-echo of a spin-$\frac 1 2$ particle and quantum phase transition in a spin-chain, which couples to the particle. The Hahn echo is calculated and discussed at zero as well as at finite temperatures. On the example of XY model, we show that the critical points of the chain are marked by the extremal values in the Hahn echo, and influence the Hahn echo in surprising high temperature. An explanation for the relation between the echo and criticality is also presented.Comment: 5 pages, 6 figure

Biharmonic Riemannian submersions from 3-manifolds

An important theorem about biharmonic submanifolds proved independently by Chen-Ishikawa [CI] and Jiang [Ji] states that an isometric immersion of a surface into 3-dimensional Euclidean space is biharmonic if and only if it is harmonic (i.e, minimal). In a later paper [CMO2], Cadeo-Monttaldo-Oniciuc shown that the theorem remains true if the target Euclidean space is replaced by a 3-dimensional hyperbolic space form. In this paper, we prove the dual results for Riemannian submersions, i.e., a Riemannian submersion from a 3-dimensional space form of non-positive curvature into a surface is biharmonic if and only if it is harmonic