Funneling Light Through a Subwavelength Aperture with Epsilon-Near-Zero Materials

Integration of the next generation of photonic structures with electronic and optical on-chip components requires the development of effective methods for confining and controlling light in subwavelength volumes. Several techniques enabling light coupling to sub-wavelength objects have recently been proposed, including grating-, and composite-based solutions. However, experi-mental realization of these couplers involves complex fabrication with \sim 10nm resolution in three dimensions. One promising alternative to complex coupling structures involves materials with vanishingly small dielectric permittivity, also known as epsilon-near-zero (ENZ) materials. In contrast to the previously referenced approaches, a single at layer of ENZ-material is expected to provide effcient coupling between free-space radiation and sub-wavelength guiding structures. Here we report the first direct observation of bulk-ENZ-enhanced transmission through a subwavelength slit, accompanied by a theoretical study of this phenomenon. Our study opens the door to multiple practical applications of ENZ materials and ENZ-based photonic systems

Bimodal Brightness Oscillations in Models of Young Binary Systems

We consider a model for the cyclic activity of young binary stars that accrete matter from the remnants of a protostellar cloud. If the orbit of such a binary system is inclined at a small angle to the line of sight, then the streams of matter and the density waves excited in the circumbinary disk can screen the primary component of the binary from the observer. To study these phenomena by the SPH (smoothed particle hydrodynamics) method, we have computed grids of hydrodynamic models for binary systems based on which we have constructed the light curves as a function of the orbital phase.The main emphasis is on investigating the properties of the brightness oscillations. Therefore, the model parameters were varied within the following ranges: the component mass ratio q = M2 : M1 = 0.2 - 0.5 and the eccentricity e = 0 - 0.7. The parameter that defined the binary viscosity was also varied. We adopted optical grain characteristics typical of circumstellar dust. Our computations have shown that bimodal oscillations are excited in binaries with eccentric orbits, provided that the binary components do not differ too much in mass. In this case, the ratios of the periods and amplitudes of the bimodal oscillations and their shape depend strongly on the inclination of the binary plane and its orientation relative to the observer. Our analysis shows that the computed light curves can be used in interpreting the cyclic activity of UX Ori stars.Comment: 14 pages, 5 figures, 1 tabl

k-strings and baryon vertices in SU(N) gauge theories

It is pointed out that the sine law for the k-string tension emerges as the critical threshold below which the spatial Z_N symmetry of the static baryon potential is spontaneously broken. This result applies not only to SU(N) gauge theories, but to any gauge system with stable k-strings admitting a baryon vertex made with N sources in the fundamental representation. Some simple examples are worked out.Comment: 4 pages, 4 figures, v2: reference added, v3: comments and references adde

Gamow-Teller Strength in the A=14 Multiplet: A Challenge to the Shell Model

A new experimental approach to the famous problem of the anomalously slow Gamow-Teller (GT) transitions in the {beta} decay of the A = 14 multiplet is presented. The GT strength distributions to excited states in {sup 14}C and {sup 14}O was studied in high-resolution (d,{sup 2}He) and ({sup 3}He,t) charge-exchange reactions on {sup 14}N. No-core shell-model (NCSM) calculations capable of reproducing the suppression of the {beta} decays predict a selective excitation of J{sup {pi}} = 2{sup +} states. The experimental confirmation represents a validation of the assumptions about the underlying structure of the {sup 14}N ground state wave function. However, the fragmentation of the GT strength over three 2{sup +} final states remains a fundamental issue not explained by the present NCSM using a 6 {h_bar}{omega} model space, suggesting possibly the need to include cluster structure in these light nuclei in a consistent way

Динаміка активності та тривалості функціонування кріоконсервованих кріоекстракту, клітин та фрагментів плаценти в організмі експериментальних тварин

Background. Due to the fact that the regenerative medicine has been actively developing, an actual task is to study the features of functioning of biological objects in a patient’s body. Objective. The aim was to study the dynamics of human chorionic gonadotropin, alphafetoprotein secretion and biodegradation in an organism of experimental animals of cryopreserved cryoextract, suspension of cells and fragments of human placenta. Methods. After administering the cryopreserved extract, fragments and suspension of placental cells to experimental animals we determined the content of alpha-fetoprotein and human chorionic gonadotropin at days 1-3, 7, 14, 21, 28 and 60; the site of cryopreserved placental fragment transplantation was histologically examined. Results. After application of cryopreserved placental cryoextract, the test compounds were identified in the highest concentration on the first day, the period of complete elimination from the blood of animals was limited by a week. After application of cryopreserved placental cells and fragments a slow increase of the alpha-fetoprotein and human chorionic gonadotropin concentrations were observed. Maximal concentration was detected during the first week, a gradual decrease was observed to the 28th day in case of cells and 60 days – placental fragments. The results of histological study of implanted placental fragment and surrounding tissues showed preserved typical for placental villous structure; they has been determined in a body of experimental animals for a long time (up to 60 days) and. Conclusion. The acellular object (placental cryoextract) was demonstrated to cause a pronounced and maximum effect in the first day after administration, their impact on a body was limited by a week. The introduction of placental cellular and tissue structures results in a more gradual release of the studied substances, the duration of their identification is 4-9 times longer. Our findings are crucial in selecting the cryopreserved biological objects of placental origin depending on the disintegration degree when administering them in the certain clinical situation.Определение секреции хорионического гонадотропина и альфафетопротеина проводили на 1, 2, 3, 7, 14, 21, 28, 60-е сутки после введения крысам криоконсервированных криоэкстракта, клеток и фрагментов плаценты, в эти же сроки проводили гистологическое исследование места трансплантации криоконсервированного фрагмента плаценты. После введения криоконсервированного криоэкстракта плаценты исследуемые соединения выявляются в максимальной концентрации в первые сутки, продолжительность их определения ограничивается неделей. Введение клеточных и тканевых структур плаценты приводит к более плавному высвобождению исследуемых веществ, продолжительность их обнаружения в 4-9 раз дольше. Результаты исследования структуры имплантированных фрагментов плаценты и окружающих тканей показали, что они достаточно длительное время (до 60 суток) определяются в организме экспериментальных животных, сохраняя типичную для плаценты ворсинчатого структуру.Визначення секреції хоріонічного гонадотропіну і альфафетопротеїну проводили на 1, 2, 3, 7, 14, 21, 28, 60-ту добу після введення щурам кріоконсервованих екстракту, клітин і фрагментів плаценти; проводили гістологічне дослідження місця трансплантації кріоконсервованого фрагменту плаценти. Після введення кріоконсервованого екстракту плаценти досліджувані сполуки виявляються у максимальній концентрації у першу добу, тривалість їхнього визначення обмежується тижнем. Введення клітинних і тканинних структур плаценти приводить до більш плавного вивільнення досліджуваних речовин, тривалість їхнього виявлення в 4-9 разів довше. Результати дослідження структури імплантованих фрагментів плаценти і оточуючих тканин показали, що вони досить тривалий час (до 60 діб) визначаються в організмі експериментальних тварин, зберігаючи типову для плаценти ворсинчасту структуру

Dynamics of activity and duration of functioning of cryopreserved cryoextract, placental cells and fragments in the organism of experimental animals.

Background. Due to the fact that the regenerative medicine has been actively developing, an actual task is to study the features of functioning of biological objects in a patient’s body. Objective. The aim was to study the dynamics of human chorionic gonadotropin, alphafetoprotein secretion and biodegradation in an organism of experimental animals of cryopreserved cryoextract, suspension of cells and fragments of human placenta. Methods. After administering the cryopreserved extract, fragments and suspension of placental cells to experimental animals we determined the content of alpha-fetoprotein and human chorionic gonadotropin at days 1-3, 7, 14, 21, 28 and 60; the site of cryopreserved placental fragment transplantation was histologically examined. Results. After application of cryopreserved placental cryoextract, the test compounds were identified in the highest concentration on the first day, the period of complete elimination from the blood of animals was limited by a week. After application of cryopreserved placental cells and fragments a slow increase of the alpha-fetoprotein and human chorionic gonadotropin concentrations were observed. Maximal concentration was detected during the first week, a gradual decrease was observed to the 28th day in case of cells and 60 days – placental fragments. The results of histological study of implanted placental fragment and surrounding tissues showed preserved typical for placental villous structure; they has been determined in a body of experimental animals for a long time (up to 60 days) and. Conclusion. The acellular object (placental cryoextract) was demonstrated to cause a pronounced and maximum effect in the first day after administration, their impact on a body was limited by a week. The introduction of placental cellular and tissue structures results in a more gradual release of the studied substances, the duration of their identification is 4-9 times longer. Our findings are crucial in selecting the cryopreserved biological objects of placental origin depending on the disintegration degree when administering them in the certain clinical situation