1,110 research outputs found

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

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    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

    A review of infant growth and psychomotor developmental outcomes after intrauterine exposure to preeclampsia

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    Preeclampsia is a hypertensive disorder of pregnancy with serious health implications for mother and their offspring. The uteroplacental vascular insufficiency caused by preeclampsia is associated with epigenetic and pathological changes in the mother and fetus. However, the impact of preeclampsia in infancy (birth to 2 years), a time of rapid development influenced by pre- and postnatal factors that can predict future health outcomes, remains inconclusive. This narrative review of 23 epidemiological and basic science studies assessed the measurement and impact of preeclampsia exposure on infant growth and psychomotor developmental outcomes from birth to 2 years. Studies assessing infant growth report that preeclampsia-exposed infants have lower weight, length and BMI at 2 years than their normotensive controls, or that they instead experience accelerated weight gain to catch up in growth by 2 years, which may have long-term implications for their cardiometabolic health. In contrast, clear discrepancies remain as to whether preeclampsia exposure impairs infant motor and cognitive development, or instead has no impact. It is additionally unknown whether any impacts of preeclampsia are independent of confounders including shared genetic factors that predispose to both preeclampsia and childhood morbidity, perinatal factors including small for gestational age or preterm birth and their sequelae, and postnatal environmental factors such childhood nutrition. Further research is required to account for these variables in larger cohorts born at term, to help elucidate the independent pathophysiological impact of this clinically heterogenous and dangerous disease

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

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    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

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    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

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    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 ïŹndings were conïŹrmed by a signiïŹcant 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

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    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

    Childhood growth outcomes 2 years after hypertensive versus normotensive pregnancy: a P4 study

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    Background: Intrauterine exposure to hypertensive disorders of pregnancy, including gestational hypertension (GH) and preeclampsia (PE), may influence infant growth and have long-term health implications. This study aimed to compare growth outcomes of infants exposed to a normotensive pregnancy (NTP), GH, or PE from birth to 2 years. Methods: Infants were children of women enroled in the prospective Postpartum Physiology, Psychology and Paediatric (P4) cohort study who had NTP, GH or PE. Birth, 6-month (age-corrected) and 2-year (age-corrected) weight z-scores, change in weight z-scores, rapid weight gain (≄0.67 increase in weight z-score) and conditional weight gain z-scores were calculated to assess infant growth (NTP = 240, GH = 19, PE = 66). Results: Infants exposed to PE compared to NTP or GH had significantly lower birth weight and length z-scores, but there were no differences in growth outcomes at 6 months or 2 years. GH and PE-exposed infants had significantly greater weight z-score gain [95% CI] (PE = 0.93 [0.66–1.18], GH = 1.03 [0.37–1.68], NTP = 0.45 [0.31–0.58], p < 0.01) and rapid weight gain (GH = 63%, PE = 59%, NTP = 42%, p = 0.02) from birth to 2 years, which remained significant for PE-exposed infants after confounder adjustment. Conclusion: In this cohort, GH and PE were associated with accelerated infant weight gain that may increase future cardiometabolic disease risk. Impact: Preeclampsia exposed infants were smaller at birth, compared with normotensive pregnancy and gestational hypertension exposed infants, but caught up in growth by 2 years of age.Both preeclampsia and gestational hypertension exposed infants had significantly accelerated weight gain from birth to 2 years, which remained significant for preeclampsia exposed infants after adjustment for confounders including small for gestational age.Monitoring of growth patterns in infants born following exposure to a hypertensive disorder of pregnancy may be indicated to prevent accelerated weight gain trajectories and obesity

    Electric Levitation Using Δ-Near-Zero Metamaterials

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    [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 Δ-Near-Zero Metamaterials. Physical Review Letters. 112(3):33902-1-33902-5. https://doi.org/10.1103/PhysRevLett.112.033902S33902-133902-5112

    Tunable hybrid surface waves supported by a graphene layer

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    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
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