A uniform alignment of liquid crystal (LC) with finite pretilt was observed on microtextured substrates that were lithographically fabricated with alternating horizontal and vertical corrugations. As the period of alternation was decreased toward 0:8 m, the nematic LC alignment on these substrates changed from inhomogeneous in plane, copying the substrate corrugations, to a uniform configuration with a large pretilt of 40 . This transition is pertinent to a frustrated boundary wherein a lowering in the LC elastic energy due to spatial variation in the LC orientation compromises an increase in the surface anchoring energy. A model based on this idea demonstrates good agreement with the experiment. This result may open up a new arena for tailoring substrate characteristics for LC alignment. DOI: 10.1103/PhysRevLett.91.215501 PACS numbers: 61.30.Hn, 61.30.Dk, 61.30.Eb Substrate conditioning for the alignment of liquid crystal (LC) molecules is essential to the operation of LC displays. Most existing techniques used to produce the alignment effect involve uniform treatment of the substrate surface. An unconventional approach to uniform LC alignment, based on inhomogeneous patterning of the substrate, was proposed some time ago [1,2]. The idea is to create a situation wherein the LC director, in coping with the inhomogeneous substrate pattern, acquires so large an elastic energy that the LC has to compromise with a uniform configuration. In general, this frustrated boundary condition can be achieved by making the pattern period small enough. A few versions of this idea, including the use of inhomogeneous surfactant treatment [1,3] and inhomogeneous rubbing [4], have been reported successful. More recently, an interesting application of these substrates in multistable display, which may potentially lead to lower energy consumption, was demonstrated [5,6]. In these demonstrations, the LC director makes zero pretilt with the substrate, and the switching between different stable LC states was achieved by varying an in-plane electric field. However, out-of-plane switching is preferred since the electric field can be more uniform. But that requires the LC pretilt to be finite [7], which has not been found in any reported embodiments [1,3,4]. In yet some designs, a large LC pretilt is crucial as it widens the range of LC elastic constants usable, which would otherwise be too narrow to be practical [8]. Here we show that on lithographically made substrates with alternating horizontal and vertical corrugations, the nematic alignment undergoes an orientational transition that results in a large pretilt angle (40 ). A simple model used to simulate the transition not only showed good agreement with the experiment but also revealed that the polar surface energies of the frustrated boundary are only 1=10 of typical values. Weak surface anchoring energies are virtuous for lowering device energy consumption and response time [9]. Figure 1 shows a subset of the microtextured substrates employed in this study. They consist of arra...

Spatially fractionated radiotherapy (GRID) has been utilized primarily in the palliative and definitive treatment of bulky tumors. Delivered in the modern era primarily with megavoltage photon therapy, this technique offers the promise of safe dose escalation with potential immunogenic, bystander and microvasculature effects that can augment a conventionally fractionated course of radiotherapy. At the University of Maryland, an institutional standard has arisen to incorporate a single fraction of GRID radiation in large (.8 cm), high-risk soft tissue and osteosarcomas prior to a standard fractionated course. Herein, we report on the excellent pathologic responses and apparent safety of this regimen in 26 consecutive patients.

Reliable control on the pretilt alignment of nematic liquid crystal (LC) in the 30°-50°range is a well-known challenge. An unconventional approach, involving microtextured surfaces with domains favoring dissimilar LC alignments, has recently demonstrated applicability in bi-and tristable displays. These textured domains realize the so-called frustrated boundary condition in which the LC elastic energy built-up (frustration) can drive the LC alignment into macroscopic uniformity. Here we show that one can harness the frustrated boundary to achieve variable LC pretilt control up to 40°.

In a recent experiment, we uncovered an unconventional liquid crystal ͑LC͒ orientation transition on microtextured substrates consisting of alternating horizontal and vertical corrugations. When the period of alternation was decreased toward ϳ1 m, the LC alignment underwent an abrupt transition from inhomogeneous planar to a more uniform configuration with a large pretilt angle ͑ϳ40°͒. With the aid of a model based on the competition between the Frank-Oseen elastic energy and a phenomenological surface potential of the form

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Purpose This article presents a solution for continuing radiation therapy without interruption in the event of a cyberattack to the radiation oncology information systems (ROIS). This process could be easily deployed to any radiation oncology practice, with little clinical overhead or burden. Methods and Materials The solution automatically retrieves all essential information from the clinical ROIS for each under‐treatment patient and periodically (e.g., daily) saves these data to a dedicated secure server for recovery. In the event that the clinical ROIS is not functioning as a result of a cyberattack, this essential information is used to build a new secondary ROIS server to continue radiotherapy treatments until the main ROIS is recovered. Once the cyberattack threat is cleared, the clinical ROIS server is rebuilt from the institution’s enterprise backup. The newly accumulated treatment information for each patient is then exported from the secondary ROIS to bring the clinical ROIS up to date. Results The Department of Radiation Oncology at the University of Maryland Medical System implemented this solution for clinical use with the Varian ARIA ROIS in the management of ~250 daily radiotherapy treatments, inclusive of a proton center. This solution was determined to be a feasible and affordable business continuity plan for the radiation oncology practice by minimizing radiation treatment downtime to a couple of hours in a simulated cyberattack drill. Conclusions The proposed solution can achieve continuation of radiation therapy treatment without treatment breaks in the event of a cyberattack. It also provides cushion time for radiation oncology departments to rebuild their clinical ROIS systems from the enterprise data backup.

We present an accurate, efficient algorithm for calculating the effective dielectric constant ¯of periodic two-component composites with arbitrary unit-cell microstructures. The algorithm is based on a formulation of the relevant equations in the Bergman-Milton representation of ¯that enables the use of the fast Fourier transform in their solution, coupled with the sum rules of the geometric spectral function. Our approach accurately reproduces known results, such as the two-dimensional checkerboard problem, and yields excellent agreement with experimentally measured results on random configurations of metallic spheres.

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