Scaling behavior of ferroelectric FET with reduction in number of domains in ferroelectric layer

With the gate-length scaling, the number of domains in FeFET is reduced to a few or a single domain. In this paper, we investigate the effect of multi-domains versus few/single-domain behavior in FeFET. The abrupt polarization switching behavior of a single-domain is obtained by modifying the Preisach model in which the difference between saturation and remnant polarization (PsPr) is reduced. We show that for the same program/erase voltage, a two-times higher memory window can be achieved with single/few-domains FeFET than the multi-domain FeFET. Further, at fixed program/erase voltage, the scaling behavior shows improved variability due to increased polarization-induced vertical field with single-domain FeFET. We present an optimized device with a single-domain FeFET having a low operating voltage of ±2.4 V but with the same device performance that can be achieved for multi-domain FeFET having a higher operating voltage of ±5 V, which is highly promising for low power applications.

Dynamics of Eddies Generated by Sea Ice Leads

Interaction between the atmosphere and ocean in sea ice-covered regions is largely concentrated in leads, which are long, narrow openings between sea ice floes. Refreezing and brine rejection in these leads injects salt that plays a key role in maintaining the polar halocline. The injected salt forms dense plumes that subsequently become baroclinically unstable, producing submesoscale eddies that facilitate horizontal spreading of the salt anomalies. However, it remains unclear which properties of the stratification and leads most strongly influence the vertical and horizontal spreading of lead-input salt anomalies. In this study, the spread of lead-injected buoyancy anomalies by mixed layer and eddy processes are investigated using a suite of idealized numerical simulations. The simulations are complemented by dynamical theories that predict the plume convection depth, horizontal eddy transfer coefficient and eddy kinetic energy as functions of the ambient stratification and lead properties. It is shown that vertical penetration of buoyancy anomalies is accurately predicted by a mixed layer temperature and salinity budget until the onset of baroclinic instability (~3 days). Subsequently, these buoyancy anomalies are spread horizontally by eddies. The horizontal eddy diffusivity is accurately predicted by a mixing length scaling, with a velocity scale set by the potential energy released by the sinking salt plume and a length scale set by the deformation radius of the ambient stratification. These findings indicate that the intermittent opening of leads can efficiently populate the polar halocline with submesoscale coherent vortices with diameters of around 10 km, and provide a step toward parameterizing their effect on the horizontal redistribution of salinity anomalies.

Callosal fiber length scales with brain size according to functional lateralization, evolution, and development

Brain size significantly impacts the organization of white matter fibers. Fiber length scaling – the degree to which fiber length varies according to brain size – was overlooked. We investigated how fiber lengths within the corpus callosum, the most prominent white matter tract, vary according to brain size. The results showed substantial variation in length scaling among callosal fibers, replicated in two large healthy cohorts (~2000 individuals). The underscaled callosal fibers mainly connected the precentral gyrus and parietal cortices, whereas the overscaled callosal fibers mainly connected the prefrontal cortices. The variation in such length scaling was biologically meaningful: larger scaling corresponded to larger neurite density index but smaller fractional anisotropy values; cortical regions connected by the callosal fibers with larger scaling were more lateralized functionally as well as phylogenetically and ontogenetically more recent than their counterparts. These findings highlight an interaction between interhemispheric communication and organizational and adaptive principles underlying brain development and evolution.

Patience Cowie and the Inception of Modern Fault Mechanics: A Recollection

<p>Patience Cowie’s PhD thesis, conducted with me at Lamont, resulted in three papers, published in 1992, that laid the groundwork for the modern era of fault mechanics studies. In the first paper<sup>1</sup> she reasoned that a cohesive zone model provided a plausible model of fault grown provided that the width of the cohesive zone scales linearly with fault length. In that case, the Griffith instability is avoided and faults grow self-similarly in quasistatic equilibrium. This model is consistent with the existence of faults of all sizes in which displacement scales linearly with length and the fault grows by the breakdown of a damage zone at the fault tip. In the second paper<sup>2</sup> she showed that the then existing data for fault displacement and length were consistent with linear scaling for faults rupturing rock of similar strength. In the third paper<sup>3</sup> she combined the earthquake slip/length scaling law with that fault scaling law to show how faults can grow by the accumulation of slip from earthquakes.</p><p>In the subsequent thirty years much more work has been done to expand on these themes pioneered by Patience. Here I share some memories of working with Patience in those formative years.</p><p> </p><p>1          Cowie, P. A. & Scholz, C. H. Physical explanation for the displacement-length relationship of faults using a post-yield fracture mechanics model. J.       Struct. Geol. <strong>14</strong>, 1133-1148 (1992).</p><p>2          Cowie, P. A. & Scholz, C. H. Displacement-length scaling relationship for faults: data synthesis and discussion. J. Struct. Geol. <strong>14</strong>, 1149-1156 (1992).</p><p>3          Cowie, P. A., and Scholz, C.H. Growth of faults by accumulation of seismic slip. J. Geophys. Res. <strong>97(B7)</strong>, 11085-11095 (1992b).</p>

Observation of direction instability in a fiber ring laser

We report on the observation of a new phenomenon occurring in a fiber ring laser. This phenomenon is about the transition from an initially bidirectional emission of a reciprocal fiber ring laser to a unidirectional emission at a certain pump power threshold. In addition, the final direction is not predefined but appears to be randomly chosen every time the threshold is exceeded. Therefore, we term this new phenomenon direction instability. Furthermore, we provide a first discussion of how the instability threshold is influenced by the length and the loss of the cavity. We show that the threshold follows a power times length scaling, indicating a nonlinear origin.