Annihilation of exceptional points from different Dirac valleys in a 2D photonic system

Topological physics relies on Hamiltonian’s eigenstate singularities carrying topological charges, such as Dirac points, and – in non-Hermitian systems – exceptional points (EPs), lines or surfaces. So far, the reported non-Hermitian topological transitions were related to the creation of a pair of EPs connected by a Fermi arc out of a single Dirac point by increasing non-Hermiticity. Such EPs can annihilate by reducing non-Hermiticity. Here, we demonstrate experimentally that an increase of non-Hermiticity can lead to the annihilation of EPs issued from different Dirac points (valleys). The studied platform is a liquid crystal microcavity with voltage-controlled birefringence and TE-TM photonic spin-orbit-coupling. Non-Hermiticity is provided by polarization-dependent losses. By increasing the non-Hermiticity degree, we control the position of the EPs. After the intervalley annihilation, the system becomes free of any band singularity. Our results open the field of non-Hermitian valley-physics and illustrate connections between Hermitian topology and non-Hermitian phase transitions.

The authors study a liquid crystal microcavity with polarization-dependent absorption, a source of non-Hermiticity. The transition in the Hermitian topology of the spin-orbit coupling makes possible the annihilation of exceptional points.

Secukinumab demonstrates high sustained efficacy and a favourable safety profile in patients with moderate-to-severe psoriasis through 5 years of treatment (SCULPTURE Extension Study)

BACKGROUND

Secukinumab, a fully human monoclonal antibody that selectively neutralizes IL-17A, has been shown to have significant efficacy and a favourable safety profile in the treatment of moderate-to-severe psoriasis and psoriatic arthritis.

OBJECTIVE

To assess the efficacy and safety of secukinumab through 5 years of treatment in moderate-to-severe psoriasis.

METHODS

In the core SCULPTURE study, Psoriasis Area and Severity Index (PASI) 75 responders at Week 12 continued receiving subcutaneous secukinumab until Year 1. Thereafter, patients entered the extension phase and continued treatment as per the core trial. Treatment was double-blinded until the end of Year 3 and open-label from Year 4. Here, we focus on the 300 mg fixed-interval (every 4 weeks) treatment, the recommended per label dose. Efficacy data are primarily reported as observed, but multiple imputation (MI) and last observation carried forward (LOCF) techniques were also undertaken as supportive analyses.

RESULTS

At Year 1, 168 patients entered the extension study and at the end of Year 5, 126 patients completed 300 mg (every 4 weeks) treatment. PASI 75/90/100 responses at Year 1 (88.9%, 68.5% and 43.8%, respectively) were sustained to Year 5 (88.5%, 66.4% and 41%). PASI responses were consistent regardless of the analysis undertaken (as observed, MI, or LOCF). The average improvement in mean PASI was approximately 90% through 5 years compared with core study baseline. DLQI (dermatology life quality index) 0/1 response also sustained through 5 years (72.7% at Year 1 and 65.5% at Year 5). The safety profile of secukinumab remained favourable, with no cumulative or unexpected safety concerns identified.

CONCLUSION

Secukinumab 300 mg treatment delivered high and sustained levels of skin clearance and improved quality of life through 5 years in patients with moderate-to-severe psoriasis. Favourable safety established in the secukinumab phase 2/3 programme was maintained through 5 years.

Effect of Chlorhexidine Treatment Prior to Fiber Post Cementation on Long-Term Resin Cement Bond Strength

The purpose of this study was to evaluate the push-out bond strength of two different adhesive cements (total etch and self-adhesive) for glass fiber post (GFP) cementation in simulated, long-term service (thermocycling) when the root canal is treated with chlorhexidine before cementation. One hundred twenty premolar specimens with a single root canal were selected, endodontically treated, and shaped for GFP cementation (n=120). The specimens were randomly placed into one of 12 groups (10 specimens each) according to cement (T = total-etch RelyX ARC or S = self-adhesive RelyX Unicem), treatment with chlorhexidine (N or Y: without or with), and number of thermal cycles (00, 20, or 40: 0, or 20,000 or 40,000 cycles): 1. TN00, 2. TN20, 3. TN40, 4. TY00, 5. TY20, 6. TY40, 7. SN00, 8. SN20, 9. SN40, 10. SY00, 11. SY20, 12. SY40. The root of each specimen was cut perpendicular to the vertical axis, yielding six 1.0 mm-thick sections. A push-out bond strength test was performed followed by statistical analysis using a factorial analysis of variance. Pairwise comparisons of significant factor interactions were adjusted using the Tukey test. Significant differences of push-out bond strengths were found in the four main effects (resin cement [ p<0.0001], treatment with chlorhexidine [ p<0.0001], number of cycles [ p<0.0001], and root third [ p<0.0001]) and all interactions ( p<0.05 for all). Both resin cements produced higher bond strength in the cervical third followed by the middle third, and lower values were detected in the apical third. Additionally, the results suggest that the use of an additional disinfection treatment with chlorhexidine before the cement application produced the highest push-out bond strength regardless of root third. Further, the thermocycling simulation decreased the bond strength for both resin cements long-term when the chlorhexidine was not applied before cementation. However, when the root canal was treated with chlorhexidine and the fiber post was cemented with self-adhesive cement, the bond strength increased after 0, 20,000 and 40,000 cycles.

Marginal Adaptation and Quality of Interfaces in Lithium Disilicate Crowns — Influence of Manufacturing and Cementation Techniques

Purpose: To evaluate the cement line thickness and the interface quality in milled or injected lithium disilicate ceramic restorations and their influence on marginal adaptation using different cement types and different adhesive cementation techniques.

Methods and Materials: Sixty-four bovine teeth were prepared for full crown restoration (7.0±0.5 mm in height, 8.0 mm in cervical diameter, and 4.2 mm in incisal diameter) and were divided into two groups: CAD/CAM automation technology, IPS e.max CAD (CAD), and isostatic injection by heat technology, IPS e.max Press (PRESS). RelyX ARC (ARC) and RelyX U200 resin cements were used as luting agents in two activation methods: initial self-activation and light pre-activation for one second (tack-cure). Next, the specimens were stored in distilled water at 23°C ± 2°C for 72 hours. The cement line thickness was measured in micrometers, and the interface quality received scores according to the characteristics and sealing aspects. The evaluations were performed with an optical microscope, and scanning electron microscope images were presented to demonstrate the various features found in the cement line. For the cement line thickness, data were analyzed with three-way analysis of variance (ANOVA) and the Games-Howell test (α=0.05). For the variable interface quality, the data were analyzed with the Mann-Whitney U-test, the Kruskal-Wallis test, and multiple comparisons nonparametric Dunn test (α=0.05).

Results: The ANOVA presented statistical differences among the ceramic restoration manufacturing methods as well as a significant interaction between the manufacturing methods and types of cement (p&lt;0.05). The U200 presented lower cement line thickness values when compared to the ARC with both cementation techniques (p&lt;0.05). With regard to the interface quality, the Mann-Whitney U-test and the Kruskal-Wallis test demonstrated statistical differences between the ceramic restoration manufacturing methods and cementation techniques. The PRESS ceramics obtained lower scores than did the CAD ceramics when using ARC cement (p&lt;0.05).

Conclusions: Milled restorations cemented with self-adhesive resin cement resulted in a thinner cement line that is statistically different from that of CAD or pressed ceramics cemented with resin cement with adhesive application. No difference between one-second tack-cure and self-activation was noted.

Push-Out Bond Strength Evaluation of Glass Fiber Posts With Different Resin Cements and Application Techniques

The purpose of this study was to evaluate the push-out strength of two different adhesive cements (total etch and self-adhesive) for glass fiber post (GFP) cementation using two different techniques (microbrush and elongation tip) of cement application. In addition, this study evaluated the effect of total-etch conditioning before the use of a self-adhesive cement. Sixty premolar specimens with a single root canal were selected, endodontically treated, and shaped for GFP cementation. The specimens were randomly placed into one of six groups according to the cement and technique used: RelyX ARC (ARC): ARC + microbrush, ARC + elongation tip; RelyX Unicem (RU): RU + microbrush, RU + elongation tip; or RelyX Unicem + 37% phosphoric acid (RUE): RUE + microbrush, RUE + elongation tip. Each specimen root was cut perpendicular to the vertical axis yielding six 1.0-mm-thick sections. Push-out strength test was performed, followed by statistical analysis using three-way analysis of variance and the Games-Howell test (p<0.05). Statistically significant differences between the groups were found (p< 0.05). The cervical third of the roots had the highest mean push-out strength values, while the apical third had the lowest mean values regardless of the technique used. The elongation technique produced higher mean push-out strength values compared to the microbrush technique. The self-etch adhesive cement had the highest mean push-out strength value in all thirds. The addition of a conditioning step before the self-etch adhesive cementation appears to be effective in enhancing push-out strength with GFPs.

Effects of preheating and precooling on the hardness and shrinkage of a composite resin cured with QTH and LED

The aim of this study was to evaluate in vitro the hardness and shrinkage of a pre-cooled or preheated hybrid composite resin cured by a quartz-tungsten-halogen light (QTH) and light-emitting diode (LED) curing units. The temperature on the tip of the devices was also investigated. Specimens of Charisma resin composite were produced with a metal mold kept under 37°C. The syringes were submitted to 4°C, 23°C, and 60°C (n=20) before light-curing, which was carried out with the Optilux 501 VCL and Elipar FreeLight 2 units for 20 seconds. The specimens were kept under 37°C in a high humidity condition and darkness for 48 hours. The Knoop hardness test was carried out with a 50 gram-force (gf) load for 10 seconds, and the measurement of the shrinkage gap was carried out using an optical microscope. The data were subjected to analysis of variance and the Games-Howell test (α=0.05). The mean hardness of the groups were similar, irrespective of the temperatures (p>0.05). For 4°C and 60°C, the top surface light-cured by LED presented significantly reduced shrinkage when compared with the bottom and to both surfaces cured by QTH (p<0.05). It was concluded that the hardness was not affected by pre-cooling or preheating. However, polymerization shrinkage was slightly affected by different pre-polymerization temperatures. The QTH-curing generated greater shrinkage than LED-curing only when the composite was preheated. Different temperatures did not affect the composite hardness and shrinkage when cured by a LED curing unit.

The Influence of Surface Standardization of Lithium Disilicate Glass Ceramic on Bond Strength to a Dual Resin Cement

In vitro studies to assess bond strength between resins and ceramics have used surfaces that have been ground flat to ensure standardization; however, in patients, ceramic surfaces are irregular. The effect of a polished and unpolished ceramic on bond strength needs to be investigated. Sixty ceramic specimens (20×5×2 mm) were made and divided into two groups. One group was ground with 220- to 2000-grit wet silicon carbide paper and polished with 3-, 1-, and ¼-μm diamond paste; the other group was neither ground nor polished. Each group was divided into three subgroups: treated polished controls (PC) and untreated unpolished controls (UPC), polished (PE) and unpolished specimens (UPE) etched with hydrofluoric acid, and polished (PS) and unpolished specimens (UPS) sandblasted with alumina. Resin cement cylinders were built over each specimen. Shear bond strength was measured, and the fractured site was analyzed. Analysis of variance (ANOVA) and Tukey post hoc tests were performed. PE (44.47 ± 5.91 MPa) and UPE (39.70 ± 5.46 MPa) had the highest mean bond strength. PS (31.05 ± 8.81 MPa), UPC (29.11 ± 8.11 MPa), and UPS (26.41 ± 7.31 MPa) were statistically similar, and PC (24.96 ± 8.17 MPa) was the lowest. Hydrofluoric acid provides the highest bond strength regardless of whether the surface is polished or not.

What is the infant mortality rate in South Africa? The need for improved data

OBJECTIVE

To review recent infant mortality and birth registration data in South Africa and to investigate geographical differences.

OUTCOME MEASURES

Estimates of infant mortality rates, proportion of births not registered, and proportion of births recorded in health services.

METHODS

1. Published infant mortality data for South Africa were collated. Demographic data from national household surveys (1993 and 1994 October Household Surveys and the 1993 Poverty Survey by the Southern African Labour and Development Research Unit (SALDRU) at UCT) were analysed using the indirect method developed by Brass. 2. Birth registration data were analysed and compared with the estimated number of births to identify regions with greater under-registration. The number of births recorded in the health services was analysed by province in order to assess and explore alternatives within health authorities that could complement the existing system.

RESULTS

1. Published estimates of infant mortality for the period from 1990 range from 40 to 71/1,000 births and estimates based on national household surveys conducted in this period from 11 to 81/1,000 births. 2. Completeness of birth registration in the nine provinces ranges from less than 10% in the Eastern Cape, North West and Northern Province to 60% in the Western Cape. An overall improvement from 19% to 60% could be achieved if births recorded through the health services were included in the vital registration system.

CONCLUSIONS

The infant mortality rate in South Africa is not known with any certainty. The extent of completeness of the birth registration system was 19%, which indicates a need for urgent improvement in order to provide key health status indicators. This study indicates that there is some potential for improving the extent of birth registration if it could be facilitated through the health service. However, this alone would not achieve complete registration.

RECOMMENDATIONS

Surveys will have to be relied upon until such time as routinely available statistics are accurate. The October Household Survey conducted annually by the Central Statistical Service as potentially an important source of health status information. It is imperative that either the design of the birth history questionnaire be improved or that it be replaced by a less frequent but more specialised demographic and health survey.

[A new model of computerized encephalovolumeter for monitoring of acute cerebrovascular insufficiency]

A new model of the computerized encephalovolumeter (EVM.IR) is presented. Infrared light is used as an information carrier enabling to follow the dynamics of intracerebral equilibrium and blood flow disorders. The authors suggest that this model would help clinical examination in the acute cerebral flow failure, and increase better evaluation of the efficiency of drugs improving cerebral blood flow. It should also help to foresee the outcome and prognosis. A new model of EVM.IR and its programs require further constructional and experimental studies before the routine use at ICUs.

[Cerebral infarction--a general-medical problem]

A knowledge of events accompanying the acute coronary failure may help understanding the acute cerebral blood flow insufficiency leading to brain infarction. Cerebral blood flow should be treated as an integral part of the systemic blood circulation. It is of importance when the disease produces lesions to the vascular wall, and the brain looses its autoregulation functions. In such a situation every extracerebral disorders--even slight--may produce extensive lesions to nervous tissue. Therefore, the treatment of the acute cerebral circulation failure requires proper functioning of all factors which may affect hemodynamics and tissue metabolism. Duration of cerebral flow disorders plays an important role in the avoidance of unfavourable complications such as brain infarction. Therefore, every physician is obliged to undertake any possible actions preventing such complications.

[Physical activity in acute cerebrovascular insufficiency]

It was noted that physical activity of 1052 patients hospitalized for the acute cerebral flow failure due to atheromatosis is an important indicator of the cerebral ischemia. Extension of ischemia evaluated on the basis of physical activity enables to foresee possible improvement and survival. Authors' own classification of physical activity may be helpful in the monitoring of cerebral flow failure therapy.

[Cost of the treatment of acute cerebrovascular insufficiency causing cerebral infarction]

Many countries are interested in the cost of therapy of the acute cerebral flow insufficiency leading to brain infarction. Total costs include: drugs, laboratory tests, nursing care, the cost of patients' food, equipment, amortization, hospital administration etc. The total expenditure for a 10-15-day treatment of the acute neurological incident depended on the severity of the disease and was 8 million ++ złoty in case of mildly ill patient, 9 million in case of moderately severe disease, and 21 million złoty in case of severely ill patient. If the costs of such tests as CT and TCD-scanning will be added, total cost will increase significantly.

[Brain stem insufficiency in acute ischemia and cerebral hemorrhage]

Consciousness disorders are closely related to the general dysfunction of the brain stem, and called by some authors brain stem insufficiency. To evaluate the degree of brain stem dysfunction, an original scale has been elaborated. Each group of brain stem functions are scored. Consciousness being the most important symptom of the brain stem insufficiency is scored about 50% in a 63-score scale. Scores are used to achieve the most objectivity in the clinical monitoring of the brain stem insufficiency. Its utility was examined in 75 patients with either ischemia or cerebral hemorrhage. Patients of both groups with severe insufficiency below 33 scores and persisting over 24 hours had no chance to survive. The authors suggest that the scores may successfully be used in the clinical monitoring of all disorders producing consciousness disturbances. Survival of patients with brain stem insufficiency in the course of cerebral ischemia or hemorrhage depends on the degree and duration of the brain stem insufficiency.