Nonlinear Control of Tunneling Through an Epsilon-Near-Zero Channel

The epsilon-near-zero (ENZ) tunneling phenomenon allows full transmission of waves through a narrow channel even in the presence of a strong geometric mismatch. Here we experimentally demonstrate nonlinear control of the ENZ tunneling by an external field, as well as self-modulation of the transmission resonance due to the incident wave. Using a waveguide section near cut-off frequency as the ENZ system, we introduce a diode with tunable and nonlinear capacitance to demonstrate both of these effects. Our results confirm earlier theoretical ideas on using an ENZ channel for dielectric sensing, and their potential applications for tunable slow-light structures

Nonlinear Control of Tunneling Through an Epsilon-Near-Zero Channel

The epsilon-near-zero (ENZ) tunneling phenomenon allows full transmission of waves through a narrow channel even in the presence of a strong geometric mismatch. Here we experimentally demonstrate nonlinear control of the ENZ tunneling by an external field, as well as self-modulation of the transmission resonance due to the incident wave. Using a waveguide section near cut-off frequency as the ENZ system, we introduce a diode with tunable and nonlinear capacitance to demonstrate both these effects. Our results confirm earlier theoretical ideas on using an ENZ channel for dielectric sensing and their potential applications for tunable slow-light structures

Accuracy of impressions with different impression materials in angulated implants

Purpose: To evaluate the dimensional accuracy of the resultant (duplicative) casts made from two different impression materials (polyvinyl siloxane and polyether) in parallel and angulated implants.Materials and Methods: Three definitive master casts (control groups) were fabricated in dental stone with three implants, placed at equi-distance. In first group (control), all three implants were placed parallel to each other and perpendicular to the plane of the cast. In the second and third group (control), all three implants were placed at 10° and 15° angulation respectively to the long axis of the cast, tilting towards the centre. Impressions were made with polyvinyl siloxane and polyether impression materials in a special tray, using a open tray impression technique from the master casts. These impressions were poured to obtain test casts. Three reference distances were evaluated on each test cast by using a profile projector and compared with control groups to determine the effect of combined interaction of implant angulation and impression materials on the accuracy of implant resultant cast.Results: Statistical analysis revealed no significant difference in dimensional accuracy of the resultant casts made from two different impression materials (polyvinyl siloxane and polyether) by closed tray impression technique in parallel and angulated implants.Conclusion: On the basis of the results of this study, the use of both the impression materials i.e., polyether and polyvinyl siloxane impression is recommended for impression making in parallel as well as angulated implants.Key words: Angulated implants, implant impression, impression accuracy, impression materia

Prevalence of psychiatric illnesses after major limb amputation and early recognition and treatment in economically lower income group patients

Background: There is high prevalence of psychiatric illness after major limb amputation and need for early recognition and treatment should be the goal but often is overlooked. Psychological support by the treating physician and the surgeon can help in adaptation to the disability but unfortunately is often overlooked.Methods: A total of 120 patients were screened for psychiatric disorder using HADS criteria Anxiety was found to be in 38 (32%) patients and depression was found to be in 27 (23%) (Table 1) (Figure 1) 55 patients had no psychiatric illness. Psychiatric illness either depression or anxiety was found to be in 65 patients.Results: In our state which is a zone of conflict between two countries prevalence of anxiety was 32% and depressive symptoms were 23%, respectively. Causative factors associated with high prevalence of psychological symptoms included unmarried young females, lower socioeconomic status, single earning member, lack of social support, unemployment, traumatic amputation. These findings were confirmed by a significant reduction of anxiety and depression scores in patients who received social support, patients with amputation due to disease, and patients with above the knee amputation.Conclusions: Our study showed higher prevalence of psychological symptoms in association with lower socioeconomic status, single earning member, lack of social support, unemployment, traumatic amputation vs amputation secondary to chronic disease. Extensive rehabilitation with the use of an interdisciplinary team approach is one of the most successful ways to return the amputee to the work place. Surgeons should give proper attention to the psychological state of amputees. Because of high prevalence of psychiatric illness after major limb amputation. It is suggested that psychiatric evaluation and adequate rehabilitation should form a part of treatment

Considerations on the effects that core material machining has on an electrical machine's performance

An often-overlooked aspect during the development process of electrical machines, is the validity and accuracy of the machine material properties being used at the design stage. Designers usually consider the data provided by the materials supplier, which is measured on material in an unprocessed state. However, the fact that the machining processes required to produce the finished product (e.g. the stator core) can permanently vary the material properties is very often neglected. This paper therefore deals with and investigates the effects that such processes can have on the overall machine performance. To do this, three sets of material data, based on 1) the materials suppliers’ data, 2) materials data based on conventional characterization methods and 3) materials data based on test samples that include the manufacturing processes, are used to develop three versions of the same baseline machine. The results of these three machines are then compared and the resulting variations of the machine’s performance presented and described. The chosen baseline machine is a high performance and relatively high speed, aerospace, electrical machine. Special attention is focused on the efficiency maps of the machine as this aspect is highly dependent on the material properties that are the most sensitive to manufacturing processes such as the material’s anhysteretic BH curve and its specific core loss

Tunable hybrid surface waves supported by a graphene layer

We study surface waves localized near a surface of a semi-infinite dielectric medium covered by a layer of graphene in the presence of a strong external magnetic field. We demonstrate that both TE-TM hybrid surface plasmons can propagate along the graphene surface. We analyze the effect of the Hall conductivity on the disper- sion of hybrid surface waves and suggest a possibility to tune the plasmon dispersion by the magnetic field.Comment: 3 pages, 3 figure

Electric Levitation Using ε-Near-Zero Metamaterials

[EN] The ability to manufacture metamaterials with exotic electromagnetic properties has potential for surprising new applications. Here we report how a specific type of metamaterial-one whose permittivity is near zero-exerts a repulsive force on an electric dipole source, resulting in levitation of the dipole. The phenomenon relies on the expulsion of the time-varying electric field from the metamaterial interior, resembling the perfect diamagnetic expulsion of magnetostatic fields. Leveraging this concept, we study some realistic requirements for the levitation or repulsion of a polarized particle radiating at any frequency, from microwave to optics.This work is supported in part by the US Office of Naval Research (ONR) Multidisciplinary University Research Initiative (MURI) Grant No. N00014-10-1-0942. F. J. R.-F. acknowledges financial support from Grant FPI of GV and the Spanish MICINN under Contracts No. CONSOLIDER EMET CSD2008-00066 and No. TEC2011-28664-C02-02.Rodríguez Fortuño, FJ.; Vakil, A.; Engheta, N. (2014). Electric Levitation Using ε-Near-Zero Metamaterials. Physical Review Letters. 112(3):33902-1-33902-5. https://doi.org/10.1103/PhysRevLett.112.033902S33902-133902-5112

Accountability, Strategy, and International Non-Governmental Organizations

Increased prominence and greater influence expose international non-governmental development and environmental organizations (INGOs) to increased demands for accountability from a wide variety of stakeholdersdonors, beneficiaries, staffs, and partners among others. This paper focuses on developing the concept of INGO accountability, first as an abstract concept and then as a strategic idea with very different implications for different INGO strategies. We examine those implications for INGOs that emphasize service delivery, capacity-building, and policy influence. We propose that INGOs committed to service delivery may owe more accountability to donors and service regulators; capacity-building INGOs may be particularly obligated to clients whose capacities are being enhanced; and policy influence INGOs may be especially accountable to political constituencies and to influence targets. INGOs that are expanding their activities to include new initiatives may need to reorganize their accountability systems to implement their strategies effectively. This publication is Hauser Center Working Paper No. 7. The Hauser Center Working Paper Series was launched during the summer of 2000. The Series enables the Hauser Center to share with a broad audience important works-in-progress written by Hauser Center scholars and researchers

High speed solid rotor permanent magnet machines: concept and design

This paper proposes a novel solid rotor topology for an Interior Permanent Magnet (IPM) machine, adopted in this case for an aircraft starter-generator design. The key challenge in the design is to satisfy two operating conditions which are: a high torque at start and a high speed at cruise. Conventional IPM topologies which are highly capable of extended field weakening are found to be limited at high speed due to structural constraints associated with the rotor material. To adopt the IPM concept for high speed operation, it is proposed to adopt a rotor constructed from semi-magnetic stainless steel, which has a higher yield strength than laminated silicon steel. To maintain minimal stress levels and also minimize the resultant eddy current losses due to the lack of laminations, different approaches are considered and studied. Finally, to achieve a better tradeoff between the structural and electromagnetic constraints, a novel slitted approach is implemented on the rotor. The proposed rotor topology is verified using electromagnetic, static structural and dynamic structural Finite Element (FE) analyses. An experiment is performed to confirm the feasibility of the proposed rotor. It is shown that the proposed solid rotor concept for an IPM fulfils the design requirements whilst satisfying the structural, thermal and magnetic limitations

Acceptability of HIV Rapid Testing in Diverse Clinical Settings in Iran

Introduction: Rapid HIV testing in clinical settings can identify previously undiagnosed persons and link them to care, as well provide patients with knowledge of their serostatus and risk reduction counseling. We conducted a survey to characterize factors affecting the acceptance or declining of rapid HIV testing among Iranian patients.Methods: This cross-sectional survey was conducted from October 2014 to December 2014 with patients in three different health care centers (an emergency department in an urban hospital, a rural health centre, a voluntary counseling and testing centre (VCT) within Imam Khomeini Hospital, Tehran, Iran and a rural health centre). Participants completed a semi-structured face-to-face questionnaire and were tested by an HIV rapid test (Chembio Sure Check).Results: Of 222 participants, 25 participants were from the urban emergency department, 40 from the urban VCT program, and 157 from the rural health care centre. All did the rapid HIV test; all were HIV negative. HIV-related risk profiles found the urban emergency department patients more likely to have multiple partners (26%, P<0.01) and history of sexually transmitted diseases (27%, P<0.001) compared to VCT patients (9% and 3%, respectively) and rural clinic patients (4% and 1%, respectively). Emergency department patients were also more willing to pay for a HIV rapid test (44%, P<0.01), doing a rapid self-test at home (84%,P=0.01), preferring pharmacies as a place for providing rapid tests (80%, P=0.001). Also level of participants’ awareness was considerably different between mentioned centres (median=11, 12, 10 for emergency department, VCT and rural Health care centre respectively; P=0.012).Conclusions: Increasing knowledge about HIV rapid testing, its availability, and keeping costs low can expand the desire to use the test and ultimately prevent the spread of HIV through lack of knowing one’s serostatus and lack of treatment. Emergency departments in urban Iran may be an opportunity to test persons at high risk for HIV infection