Reciprocal Configurations Research Articles

First contact: Fine structure of the impact flash and ejecta during hypervelocity impact.

Hypervelocity impacts are a significant threat in low-earth orbit and in hypersonic flight applications. The earliest observable phenomena and mechanisms activated under these extreme conditions are typically obscured by a very bright flash, called the impact flash, that contains the signatures of the critical mechanisms, the impacting materials, and the impact environment. However, these signatures have been very difficult to observe because of the small length and time scales involved coupled with the high intensities associated with the flash. Here we perform experiments investigating the structure and characteristics of the impact flash generated by 3 km s spherical projectile impacts on structural metals using temporally co-registered high-resolution diagnostics. Reciprocal impact configurations, in which the projectile and target material are swapped, are used to demonstrate the coupling of early-stage mechanisms in the flash and later-stage ejection mechanisms responsible for the development of the impact crater.

‘A whole society, with its own economic system’: the reciprocal and capitalist configurations of American DIY music scenes

ABSTRACT In this article, I examine the alternative economics of reciprocity in American DIY (do-it-yourself) culture. Through long term ethnographic study of local and translocal DIY scenes, including shows, spaces, and touring practices, I reveal a plethora of reciprocal musical and extra-musical activities that enable the creation of alternative DIY worlds. Yet I also highlight how these alternative economic systems of reciprocity coexist with capitalist ones. Drawing on Arjun Appadurai’s theories of value and commodity (1986), alongside other authors who examine the co-existence of different economic systems, I chart how DIY practitioners tactically navigate the boundaries between these reciprocal and capitalist economic systems and worlds. These socio-economic relations, I argue, also shape DIY sounds and aesthetics, as well as contribute to distinct musical values, discourses and practices.

HUBUNGAN TINGKAT KECEMASAN DENGAN KUALITAS TIDUR MAHASISWA DALAM PENYUSUNAN TUGAS AKHIR DI MASA PANDEMI COVID-19 DI AKADEMI KEPERAWATAN JUSTITIA

Students who are organizing their final assignments face different mental problems such as anxiety and sleep quality problems. According to information from WHO, the most widely recognized mental problems with predominance are anxiety and sadness problems, where there are more than 200 million people (3.6% of the population) who experience the adverse effects of anxiety problems. The reason is to determine the relationship between the level of anxiety and the nature of student sleep in planning the last activity during the Coronavirus pandemic at Justitia Nursing Academy. This examination is a quantitative exploration with different reciprocal examination configurations using a cross sectional methodology. This testing strategy uses complete examination, where the number of tests is equivalent to the population. The showed that most of the 24 respondents experienced moderate anxiety up to 10 respondents (41.7%). From effect of concentrate on sleep quality, it shows that most of the respondents' sleep quality is not good, namely 11 respondents (45.8%). From the results after the Spearman connection test, it was obtained a large value of 0.000 which indicates that the relationship between anxiety levels and sleep quality is very important with Spearman's relationship of 0.788 which indicates that the connection is positive with a strong connection strength. Some students who completed their final assignments experienced moderate anxiety and poor sleep quality, with the Corona virus pandemic which caused limited space for development, and mental problems that became negative thoughts such as stress.

Distichon (Distich)

The verse form Distichon (distich), a classical couplet comprising one hexameter and one pentameter line, can qualify as a Begriff (concept) in Clark Muenzer’s sense of an “experimental technology” that facilitates the intelligibility of a world in flux. Goethe experimented with this ancient form throughout the decade following his return from his first journey to Italy and developed it into a fine-tuned vehicle for his emerging natural scientific and cultural conceptions. While he drew from both the elegiac and epigrammatic distichal traditions, the epigram, in particular, shaped his conceptualization of the distich as a primal poetic unit mediating the poet’s encounter with the world. The flexible segmented structure of the distich, as defined by its two lines and caesuras, nicely accommodates parallel, contrastive, reciprocal, circular, and triadic configurations that play a role in his morphological thought and aesthetic-cultural program.

Realization of historical Persian ornamental and geometric patterns as architectural components in innovative reciprocal frame barrel vaults

Barrel vaults are one of the most widely used forms in Persian architecture. While they are mainly built with heavy and compressive materials such as brick, today’s advances in construction techniques has led the architectural industry to utilize lightweight structural systems including reciprocal frame structures (RF). The purpose of this paper is to generate a barrel vault form using RFs through a revival of historical Persian ornamental and geometric patterns known as girih. This research was carried out in three phases. After extracting the essential criteria necessary to produce reciprocal configuration, four geometric girih that were compatible with those criteria were selected. The selected patterns were then modified to localize their reciprocal configurations following the Persian ornamental and geometric patterns. A structural analysis was performed using the Karamba Plugin in order to make a structural comparison between a barrel vault constructed with RFs and one made with bricks. The results showed that the use of RFs can significantly reduce the structural weight while using a minimum of material in covering the specified span. In addition, it was concluded that the vault with Hasht-e-moraba and Chahar-lenge ghenas patterns behaved in a more optimal way for the transmission of axial forces with less displacement and deformation.

Analytical modeling of one-dimensional resonant asymmetric and reciprocal acoustic structures as Willis materials

As building blocks of acoustic metamaterials, resonant scatterers have demonstrated their ability to modulate the effective fluid parameters, which subsequently possess extreme properties such as negative bulk modulus or negative mass density. Promising applications have been shown such as extraordinary absorption, focusing, and abnormal refraction for instance. However, acoustic waves can be further controlled in Willis materials by harnessing the coupling parameters. In this work, we derive the closed forms of the effective parameters from the transfer matrix in three asymmetric and reciprocal one-dimensional resonant configurations and exhibit the differences in terms of coupling coefficients. The way in which Willis coupling occurs in spatially asymmetric unit cells is highlighted. In addition, the analysis shows the absence of odd Willis coupling for reciprocal configurations. These effective parameters are validated against experimental and numerical results in the three configurations. This article paves the way of a novel physical understanding and engineering use of Willis acoustic materials.

Direction reconfigurable nonreciprocal acousto-optic modulator on chip

Nonreciprocal components are essential in photonic systems for protecting light sources and for signal routing functions. Acousto-optic methods to produce nonreciprocal devices offer a foundry-compatible alternative to magneto-optic solutions and are especially important for photonic integration. In this paper, we experimentally demonstrate a dynamically reconfigurable nonreciprocal acousto-optic modulator at the telecom wavelength with a peak contrast of 8 dB and a 3 dB bandwidth of 1.1 GHz. The modulator can be arranged in a multitude of reciprocal and nonreciprocal configurations by means of an external RF input. The dynamic reconfigurability of the device is enabled by a new cross-finger interdigitated piezoelectric transducer that can change the directionality of the reciprocity-breaking acoustic excitation based on the phase of the RF input. The methodology we demonstrate here may enable new avenues for direction dependent signal processing and optical isolation.

Determination of static and kinematic determinacy of pin-jointed assemblies using rigid-body displacements as primary unknown variables

The traditional methods taking nodal displacements as primary unknown variables are only applicable to the determination of the static and kinematic determinacy of pin-bar assemblies. For other types of pin-jointed assemblies, such as reciprocal configurations, traditional methods are no longer valid for determining their static and kinematic determinacy. In order to tackle the problem, this paper proposes a new generic method by taking the rigid-body displacements of each element as primary unknown variables. On the basis of the ‘dislocations’ compatibility at the articulated points in the configurations, the compatibility equations are derived and then kinematic matrix is obtained. Meanwhile, the forces at the articulated points of the elements are also chosen as primary unknown variables, and then the equilibrium equations at the reference point in the elements are derived to give the associated equilibrium matrix. From matrix computations for the obtained kinematic matrix and equilibrium matrix, the static and kinematic determinacy of the configurations can be determined. Furthermore, the geometric nonlinearity of the articulated mechanisms is considered, and then the exact kinematic governing equations and higher-order displacement compatibility conditions are established. Finally, several numerical examples are employed to demonstrate the effectiveness of the proposed new generic method for determining the static and kinematic determinacy. The results from the proposed method are then examined by those from traditional methods and finite element analyses. From the results for numerical examples, the first-order infinitesimal mechanisms occur in the planar reciprocal configurations assembled from regular triangles and the Archimedes tiling, while the curved reciprocal configurations with the same topologies have no redundant restraints and are thus geometrically stable.

The metabolic rate of cultured muscle cells from hybrid Coturnix quail is intermediate to that of muscle cells from fast-growing and slow-growing Coturnix quail.

Growth rate is a fundamental parameter of an organism's life history and varies 30-fold across bird species. To explore how whole-organism growth rate and the metabolic rate of cultured muscle cells are connected, two lines of Japanese quail (Coturnix coturnix japonica), one that had been artificially selected for fast growth for over 60 generations and a control line were used to culture myoblasts. In line with previous work, myoblasts from the fast growth line had significantly higher rates of oxygen consumption, glycolytic flux, and higher mitochondrial volume than myoblasts from the control line, indicating that an increase in growth rate is associated with a concomitant increase in cellular metabolic rates and that mitochondrial density contributes to the differences in rates of metabolism between the lines. We reared chicks from two hybrid lines with reciprocal parental configurations for growth rate to explore the effect of maternally inherited mitochondrial DNA on rates of growth and metabolism. Growth rates of chicks, cellular basal oxygen consumption, glycolytic flux, and mitochondrial volume in myoblasts from chicks from both reciprocal crosses were intermediate to the fast and control lines. This indicates that genes in the nucleus have a strong influence on metabolic rates at the cellular level, compared with maternally inherited mitochondrial DNA.

Electromagnetic wave propagation in (bianisotropic) magnetoelectric materials

The propagation of electromagnetic plane waves in linear magnetoelectric materials is studied. The wave equation is derived as a generalized two-dimensional eigenvalue problem, and a method of calculating the propagating wave modes is presented. An analytic dispersion relation for general bianisotropic materials is given. Additionally, an analytic model is presented, which decomposes electric and magnetic fields into coupled and uncoupled components. This model provides a methodology for characterizing the coupled field parameters in terms of the polarizations induced by cross-coupling effects in magnetoelectric materials. From this formulation, the interactions of applied fields in magnetoelectric materials are contrasted with conventional material counterparts. This is then used to characterize the fields in terms of polarizations induced by the uncoupled components and cross-coupling parameters. Reciprocal and nonreciprocal configurations of magnetoelectric materials are identified. The similarities and differences of nonreciprocal magnetoelectric materials to Faraday materials are described. Directional dependence of the propagating modes is shown graphically and described.

Prediction of hybrid performance in maize using molecular markers and joint analyses of hybrids and parental inbreds

The identification of superior hybrids is important for the success of a hybrid breeding program. However, field evaluation of all possible crosses among inbred lines requires extremely large resources. Therefore, efforts have been made to predict hybrid performance (HP) by using field data of related genotypes and molecular markers. In the present study, the main objective was to assess the usefulness of pedigree information in combination with the covariance between general combining ability (GCA) and per se performance of parental lines for HP prediction. In addition, we compared the prediction efficiency of AFLP and SSR marker data, estimated marker effects separately for reciprocal allelic configurations (among heterotic groups) of heterozygous marker loci in hybrids, and imputed missing AFLP marker data for marker-based HP prediction. Unbalanced field data of 400 maize dent x flint hybrids from 9 factorials and of 79 inbred parents were subjected to joint analyses with mixed linear models. The inbreds were genotyped with 910 AFLP and 256 SSR markers. Efficiency of prediction (R (2)) was estimated by cross-validation for hybrids having no or one parent evaluated in testcrosses. Best linear unbiased prediction of GCA and specific combining ability resulted in the highest efficiencies for HP prediction for both traits (R (2) = 0.6-0.9), if pedigree and line per se data were used. However, without such data, HP for grain yield was more efficiently predicted using molecular markers. The additional modifications of the marker-based approaches had no clear effect. Our study showed the high potential of joint analyses of hybrids and parental inbred lines for the prediction of performance of untested hybrids.

Covariance operators, Green functions, and canonical stochastic electromagnetic fields

In this paper, we show that for a large class of lossless reciprocal configurations, a “canonical” stochastic electromagnetic field can be defined such that its spatial covariance is proportional to the real part of the Green tensor function of the configuration. This result generalizes some relations between stochastic plane waves and free space Green functions which are well known in theoretical physics. A special application of the ideas presented here is elaborated for the configuration of a semi‐infinite, short‐circuited waveguide. It is shown that the canonical stochastic electromagnetic field in that case is a pseudoisotropic plane wave corresponding to a very special stochastic linear combination of propagating modes only. This has important consequences for the electromagnetic theory of so‐called mode‐stirred chambers.

Configuration analysis of the Schatz linkage

This paper investigates different configurations of the Schatz linkage based on the analysis of a reciprocal screw and of the relationship between the reciprocal screw and its stem-screw system, which consists of twists of freedom located at six revolute joints of the linkage. A new method of using cofactors of an augmenting screw is used to obtain the reciprocal screw. The stem-screw system of order 5 of the linkage is developed from the special geometry of the six revolute joints and closed-form displacement solutions are provided based on the stem-screw system. The screw surface representing the trajectory of the reciprocal screw with a chosen pitch is established. This surface is then used to characterize zero-pitch reciprocal screw configurations. The special relationship between the reciprocal screw and the stem-screw system is analysed and used to characterize the constraint wrench and configurations created by the changes of the constraint wrench with a non-zero pitch. Consequently, a set of configurations are presented in conjunction with a ruled surface produced by the progression of the constraint wrench when the linkage drive joint rotates from 5° to 85°.

Reciprocal and quasi-reciprocal Brillouin fiber-optic current sensors

A novel current sensor based on the interaction between two counter-propagating Brillouin fiber-optic lasers has been investigated. Polarization problems specific to current sensors are addressed and are solved by means of a mechanically twisted fiber-ring resonator including a polarization controller. The two proposed reciprocal and quasireciprocal configurations shows a linear response with a sensitivity of 126 Hz/A that is very close to the maximum sensitivity obtained by using fibers without linear birefringence. The limitations of the reciprocal configuration due to the lock-in range, the Kerr effect induced by the pump walk-off and by the pump intensity fluctuations are fully characterized. These limitations are compared with the limitations due to thermal drifts of the quasireciprocal configuration which allows direct detection of the current direction.

Absence of translocation induction in mouse stem cell spermatogonia by chemical mutagens probably due to selective elimination.

In order to discriminate between different mechanisms put forward to explain the low observed yields of reciprocal translocation configurations at diakinesis-metaphase I spermatocytes following treatment of mouse stem cell spermatogonia with chemical clastogens, the physiological states of stem cells at the moment of treatment were modified. The cell cycle was shortened by pretreatment with 2 Gy of X-rays and/or the DNA repair capacity inhibited by pretreatment with 3-aminobenzamide. Using these conditions the induction of translocations by ethyl methanesulfonate, N-ethyl-N-nitrosourea, methyl methanesulfonate and Adriamycin was studied. The results indicate that selective elimination of aberration carrying cells is probably to a large extent responsible for the low induction rate of translocations in stem cells by chemical clastogens. The high ratio of simple chromosome breaks versus chromosome exchange type aberrations induced by chemical mutagens might be the main cause of the selective elimination.

An extension of the reciprocity theorem to include high-level injection conditions

The general proof of the Ebers-Moll reciprocity theorem is extended to include high-level injection conditions in bipolar base regions. The theorem, originally derived for the low-level case, is shown to be valid in the high-level limit, as long as the emitter injection efficiency is sufficiently high in both reciprocal configurations.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A COMPARISON OF TRANSIENT VOLTAGE DECAY CURVES OBTAINED WITH DIFFERENT ELECTRODE ARRAYS AND CONFIGURATIONS OVER A MINERALIZED ZONE

AbstractThe Huntec Mark 3 time domain equipment provides information from which the nature of the transient voltage decay curves may be determined. A zone of disseminated mineralization extending above a normal fault zone was selected for a comparative study of decay curves.In a preliminary study in which steel stakes were used as current electrodes it was observed that at some stations the decay curves obtained with reciprocal dipole‐dipole configurations were significantly different and that many decay curves initially increased from low values indicating the presence of a negative component.It was assumed that the decay curves were composite and were composed of the superposition of transient voltage components due to electromagnetic and polarization effects which could be described in terms of simple exponential functions. The initial negative component was thought to be an electromagnetic effect, but when the traverses were repeated using porous pots as current electrodes it was found that the initial negative component was usually completely eliminated, indicating that it was due to negative polarization arising from the steel stakes.When the effect of the current electrode polarization was completely eliminated identical decay curves were obtained with the reciprocal array configurations, but the remaining decay curve‐which is due to induced ground polarization—cannot be described by a single simple exponential function. It is also demonstrated that the initial negative component due to stake polarization may also be present in decay curves obtained with gradient arrays indicating that separation of the current and potential electrodes does not avoid this effect which may significantly modify the decay curve in certain circumstances up to three seconds after switch‐off.

The effect of hypothermia on the induction of chromosomal mutations by acute X-irradiation of mice

Small mammals can survive cooling to o°, at which temperature their tissues are virtually anoxic. Thus hypothermia provides a method for studying the role of oxygen tension differences in determining genetic radiosensitivity of different mammalian germ-cell stages. Male mice were given 600 rad acute X-irradiation when hypothermic or at normal body temperature. In mice irradiated when hypothermic the yield of dominant lethal mutations from treated spermatozoa was slightly but not significantly reduced, while the incidence of cytologically identifiable reciprocal translocation configurations in primary spermatocytes derived from irradiated A type spermatogonia was halved (8.3% instead of 17.1%). The usual post-radiation sterile period after 600 rad was abolished in the males made hypothermic and the testis weights showed less reduction than in those given X-rays alone. This evidence for the protection of spermatogonia from somatic and genetic radiation injury by hypothermia shows that oxygen tension differences are important in determining the extent of both types of damage in these immature germ cells. With mature germ cells, however, these and previous findings agree in showing that hypothermia or other methods of oxygen deprivation provide little if any protection from genetic radiation damage to spermatozoa, presumably because they are normally hypoxic.