Sidereal Year Research Articles

The Annual Difference: How a Four-Century Debate between Confucian, Daoist, and Buddhist Thinkers on a Problem of Classical Exegesis Shaped a Predictive Mathematical Construct

In China, the precession of the equinoxes was conceptualized as an “annual difference” (suicha 歲差) between the tropical and sidereal year. The idea was introduced in the fourth century, it saw universal acceptance from the eighth century on, and it was in the four centuries in between that it was tried, debated, and spread whilst a Mediterranean-origin concept thereof arrived from India. Its four-century journey from fringe idea to universal truth is a well-studied point of interest in the history of astronomy. In this article, we will shift focus to the idea’s polymathic protagonists and epistemic foundations to explore how a scientific idea was born, debated, transmitted, and taught in Confucian commentary and, no less important, how politics, geography, regional schools, foreign transmission, and the Buddhist and Daoist religions shaped how thinkers engaged with it as individuals and as communities. Inspired by the work of Chen Kanli and Randall Collins, the goal is to show that there is nothing simple or inexorable about how even an empirically useful tool of predictive astronomical modeling is received in the relevant expert community, as it is but one element in a complex network of people and ideas aligning and opposing in ever-evolving strategies to assert relevance.

A Circannual Clock Drives Expression of Genes Central for Seasonal Reproduction

Animals living in temperate zones anticipate seasonal environmental changes to adapt their biological functions, especially reproduction and metabolism. Two main physiological mechanisms have evolved for this adaptation: intrinsic long-term timing mechanisms with an oscillating period of approximately 1 year, driven by a circannual clock [1], and synchronization of biological rhythms to the sidereal year using day length (photoperiod) [2]. In mammals, the pineal hormone melatonin relays photoperiodic information to the hypothalamus to control seasonal physiology through well-defined mechanisms [3-6]. In contrast, little is known about how the circannual clock drives endogenous changes in seasonal functions. The aim of this study was to determine whether genes involved in photoperiodic time measurement (TSHβ and Dio2) and central control of reproduction (Rfrp and Kiss1) display circannual rhythms in expression under constant conditions. Male European hamsters, deprived of seasonal time cues by pinealectomy and maintenance in constant photoperiod, were selected when expressing a subjective summer or subjective winter state in their circannual cycle of body weight, temperature, and testicular size. TSHβ expression in the pars tuberalis (PT) displayed a robust circannual variation with highest level in the subjective summer state, which was positively correlated with hypothalamic Dio2 and Rfrp expression. The negative sex steroid feedback was found to act specifically on arcuate Kiss1 expression. Our findings reveal TSH as a circannual output of the PT, which in turn regulates hypothalamic neurons controlling reproductive activity. Therefore, both the circannual and the melatonin signals converge on PT TSHβ expression to synchronize seasonal biological activity.

Measuring deep time: the Sidereal Year and the Tropical Year in Maya inscriptions

AbstractMaya inscriptions contain numerous examples of long intervals of time that count both backward and forward from a fixed point of historical reference to specific mythological dates, often thousands of years in the past or future. This paper considers the evidence that these intervals incorporated precise calculations of both the sidereal year and the tropical year. Furthermore, it outlines a specific methodology for assessing the likelihood that these distance numbers were either intentionally calculated to incorporate these astronomical measurements, or if these results are merely coincidental.

Neuroanatomical plasticity in the gonadotropin‐releasing hormone system of the ewe: Seasonal variation in glutamatergic and γ‐aminobutyric acidergic afferents

Temperate zone animals time the onset of reproductive events to coincide with specific portions of the sidereal year. Although the neural mechanisms involved remain poorly understood, a marked annual variation in the brain's sensitivity to estradiol negative feedback is thought to mediate many of the changes in neuroendocrine hormone secretion, especially that of the gonadotropin-releasing hormone (GnRH) neurons, via neural afferents. The aim of the present study was to determine whether glutamatergic inputs to GnRH neurons in sheep vary seasonally and to expand our previous observations of seasonal changes in gamma-aminobutyric acid (GABA)-ergic inputs. Brains from adult sheep were collected during the breeding season (N = 8) or the nonbreeding season (anestrus; N = 7). Confocal microscopy and optical sectioning were used to quantify the density of labeled VGLUT2 and VGAT immunoreactivity onto GnRH neurons. The results reveal a significantly greater number of VGLUT2-ir inputs to GnRH dendrites during the breeding season vs. the nonbreeding season but no seasonal changes on GnRH cell somas. The number of VGAT-ir terminals onto GnRH dendrites was reduced in the breeding season compared with the nonbreeding season. GnRH neurons were also found to receive dual-phenotype (VGLUT + VGAT) inputs; these varied with season in a manner similar to VGAT inputs. Morphologically, the numbers of branches of proximal dendrites increased significantly in a subset of GnRH neurons located near the midline. Together these results reveal a dynamic seasonal reorganization of identified inputs onto GnRH neurons and lend additional support to the overall hypothesis that seasonal modulation of GnRH neurons involves glutamatergic and GABAergic neural plasticity.

한국, 일본, 중국의 역사 기록에 나오는 별똥만발 기록의 새로 고친 목록

한국, 일본, 중국의 옛 역사 기록에 나오는 벌똥만발 기록(meteor outbursts즉, 강한 별똥비 및 별똥 소나기 기록) 가운데 신뢰할 만한 것을 모은 목록을 새로 고쳐 만들었다. 이 고친 목록에서는 지구의 세차운동과 근일점이동에 의한 영향을 받지 않고 별찌흐름(meteor stream)의 공간적 위치를 연구하기 위해 별똥만발이 나타난 시각을 나타내는데 새로운 시간 좌표계를 도입하였다. 즉 임의로 지구의 2000년 근일점을 기준으로 각 기록의 관측 시각이 항성년 단위로 끊을 때 나머지가 며칠인지를 가지고 시간 좌표계를 정의하여 사용하였다. 또한 개별 별똥 기록으로 취급되어 별똥비 항목에서 누락되었던 중국 기록 19개를 찾아내서 목록에 추가했다. 우리는 새로 개정된 별똥만발 목록에서 지난 2천년 동안 별똥만발 현상을 일으킨 별찌흐름들은 물병자리 에타 별찌흐름, 오리온자리 별찌흐름, 페르세우스자리 별찌흐름, 사자자리 별찌흐름임을 확인하였다. 세 나라의 옛 별똥만발 기록만을 대상으로 할 때, 각 별똥만발들의 가장 오랜 기록들을 약간 수정하였다. 우리는 이러한 별똥만발 현상들을 일으키는 어미혜성이 핼리형 혜성(Halley-type comet)임에 주목하고 논의하였다. We made a revised catalogue for reliable records of meteor outbursts that were recorded in Korean, Japanese, and Chinese chronicles. In order to avoid the effects of both Earth's precession and perihelion shift, we introduced a new time-coordinate of records, or the number of days elapsed within the sidereal year of the record for a given origin of time or the perihelion passage time of the you 2000. We added nineteen new records of meteor showers that are wrongly classified i, individual meteors in a Chinese archive. We found that the <TEX>${\eta}-Aquarids,$</TEX> the Perseids, the Orionids, and the Leonids have been active during the last two millennia. Due to the change of time-coordinate, the oldest record of each long-lasting meteor shower has been slightly corrected. We discuss that these long-lasting meteor showers belong to the Halley-type comets.

Nonlinear detection algorithm for periodic signals in gravitational wave detectors

We present an algorithm for the detection of periodic sources of gravitational waves with interferometric detectors that is based on a special symmetry of the problem: the contributions to the phase modulation of the signal from the earth rotation are exactly equal and opposite at any two instants of time separated by half a sidereal day; the corresponding is true for the contributions from the earth orbital motion for half a sidereal year, assuming a circular orbit. The addition of phases through multiplications of the shifted time series gives a demodulated signal; specific attention is given to the reduction of noise mixing resulting from these multiplications. We discuss the statistics of this algorithm for all-sky searches (which include a parameterization of the source spin-down), in particular its optimal sensitivity as a function of required computational power. Two specific examples of all-sky searches (broad-band and narrow-band) are explored numerically, and their performances are compared with the stack-slide technique (P. R. Brady, T. Creighton, Phys. Rev. D, 61, 082001).

Periodic signatures for the detection of cosmic axions.

In a Sikivie-type cosmic-axion detector, both the width and position of the microwave signal due to axion-photon conversion depend upon the motions of the earth. Due to the orbital and rotational motions of the earth they will be modulated with periods of 1 sidereal day and 1 sidereal year, with amplitudes of about 0.1 percent and 5 percent respectively. Because of the intrinsically-high energy resolution of Sikivie-type detectors such periodic variations should be detectable. Such modulations would not only aid in confirming the detection of cosmic axions, but, if found, would also provide important information about the distribution of axions in the halo.

Time of the sidereal year affects responsiveness to the phase-resetting effects of photoperiod in the ewe.

Two groups of ovary-intact ewes were placed in separate photochambers on the day of the vernal equinox (VE). One group was exposed to a 16 h light:8 h dark (16L:8D) photoperiod and the other to 8L:16D. On the day of the summer solstice (SS) and at 90-91-day intervals thereafter [autumnal equinox (AE), winter solstice (WS), VE and SS], each group was changed to the opposite photoperiod. The latent period between each change and either onset or cessation of cycles, as determined by measuring blood progesterone concentrations, was recorded. The latent period between change to 8L:16D and onset of cycles was shortest after the exposure at AE and longest after exposure at WS (P less than 0.001). The latent period after AE was shorter (P less than 0.001) than after VE. The correlations were small between ambient temperature and interval to onset of cycles. The latent period to cessation of cycles in response to 16L:8D was shorter after SS exposure than after WS exposure (P less than 0.01), but other differences were not significant. There was a strong (r = -0.94, P less than 0.05) negative correlation between interval to cessation of cycles and ambient temperature. Cessation of cycles in response to 16L:8D occurred more rapidly (P less than 0.001) than onset in response to 8L:16D. These results show that responsiveness to the inductive effects of photoperiod varies significantly with time of the sidereal year.