A Revision of the Star Tables in the Mumtaḥan Zīj

The table of 24 stars in one of the two extant manuscripts of the Mumtaḥan zīj is the earliest non-Ptolemaic star table in medieval Middle Eastern astronomy. Dated to 829 AD, it is a fruit of the two systematic observational programs carried out by a group of astronomers in Baghdad and Damascus in the early ninth century. In this study, the accuracy of this table is examined, showing the existence of an obvious systematic negative error in the longitude values. The manuscripts also contain another table of 18 stars, all of which also appear in the first table, in which the longitudes are updated for 1011 AD. This table is further updated for 1231 AD in the Īlkhānī zīj, the official product of the observational programs in the Maragha observatory, northwestern Iran, in the 1260s, where it is ascribed to Ibn al-A‘lam (d. 985 AD). In this paper, some verifiable and convincing proofs are provided for the hypothesis that the second Mumtaḥan star table is quite probably a refinement of the first table made by Ibn al-A‘lam on the basis of a few stellar observations by himself dated to about 976 AD. Firm evidence for one of these observations, namely of Regulus (α Leo), is provided by his younger contemporary Ibn Yūnus (d. 1009 AD)

The Observational Instruments at the Maragha Observatory after AD 1300

The present paper introduces, investigates, analyses, and comments on an anonymous treatise in Persian named al-Risāla al-Ghāzāniyya fi ’l-ālāt alra ½×diyya, “Ghāzān’s (or Ghāzānid) treatise on the observational instruments”, which describes the structure, construction, and functions of twelve “new” observational instruments in the medieval period that appear to have been proposed and invented during the reign of Ghāzān Khān, the seventh Ilkhan of the Ilkhanid dynasty of Iran (21 October 1295–17 May 1304). In the sections below we consider the treatise in the light of two issues: (1) the assumption that the primary historical sources may contain interesting notes and claims concerning Ghāzān Khān’s astronomical activities and especially the new observatory that he founded in Tabriz, and (2) the fact that at present there are hardly any sound and historically reliable accounts of the activities of the Maragha Observatory from around 1280 onwards. It is thus essential to explore the issues that constitute the principal historical features of the research, i.e., Ghāzān, the Maragha Observatory, and astronomical activities, and to clarify the contextual relations between them. In what follows we present the key historical facts (derived from the primary sources) regarding Ghāzān and his connection to both astronomy and the Maragha Observatory. Second, we describe the Maragha Observatory in the period in question, giving further details about the observational programs conducted there and noting the substantial differences between them. These data cast new light on the activities of the observatory and, as we shall see below, may challenge the established history. We then examine the treatise, its contents, the manuscripts available, and the original approach applied to the design and construction of the instruments. In the final section, we examine the notes (and the possible misunderstandings as well) deduced from the treatise as regards the instruments, their physical construction, and their relation to Ghāzān and the Maragha Observatory. The section also contains two open discussions on the only possible archaeological evidence for the instruments and the authorship of the treatise. The most important evidence is, of course, provided by the instruments themselves and the new approach applied to their design and construction, which we discuss in the second part of the paper along with a classification of the different types of the instruments. We describe the configuration and functions of each instrument separately. These two sections are based on the text; a few changes in the order and arrangement of the materials are introduced to give a fuller account of each instrument in relation to the original text. These are followed by a separate section containing critical comments on the instrument with regard to either technical or historical considerations, including critical remarks such as probable mistakes or omissions in the treatise and some suggestions for corrections and completions, an analysis of our author’s claim concerning the superiority of a new instrument over its precursors, the applicability of each instrument, the comparison of a new instrument with similar historical counterparts, and so on

Muḥyī al-Dīn al-Maghribī’s Measurements of Mars at the Maragha Observatory

Muḥyī al-Dīn al-Maghribī (d. 1283 AD) carried out a systematic observational programme at the Maragha observatory in northwestern Iran in order to provide new measurements of solar, lunar, and planetary parameters, as he explains in his treatise Talkhīṣ al-majisṭī (Compendium of the Almagest). His project produces a new and consistent set of parameters. On the basis of his four documented observations of Mars, carried out in 1264, 1266, 1270, and 1271 AD, he measured the unprecedented values for the radius of the epicycle, the longitude of the apogee, and the mean motion in longitude of the planet and also confirmed that Ptolemy’s value for its eccentricity was correct for his time. This paper presents a detailed, critical account of Muḥyī al-Dīn’s measurements. Using a criterion described below, we compare the accuracy of his values for the structural parameters of Mars with that of other historically important values known for these parameters from medieval Middle Eastern astronomy from the early eighth to the late fifteenth century. Muḥyī al-Dīn attained a higher degree of precision in his theory of Mars established at Maragha than the majority of his predecessors; the results were also more accurate than those established in his earlier zīj written in Damascus in 1258 AD and used in the official astronomical tables produced at the Maragha observatory, the Īlkhānī zī

Simple generalizations of Anti-de Sitter space-time

We consider new cosmological solutions which generalize the cosmological patch of the Anti-de Sitter (AdS) space-time, allowing for fluids with equations of state such that $w\neq -1$. We use them to derive the associated full manifolds. We find that these solutions can all be embedded in flat five-dimensional space-time with $--+++$ signature, revealing deformed hyperboloids. The topology and causal-structure of these spaces is therefore unchanged, and closed time-like curves are identified, before a covering space is considered. However the structure of Killing vector fields is entirely different and so we may expect a different structure of Killing horizons in these solutions.Comment: 6 Pages, 5 Figures, Corrections and additions made for publication in Journal of Classical and Quantum Gravit

Sediment Loading and Water Quality of Field Run-off Water

Intensive tillage is commonly employed in many agronomic production systems in the United States. Tillage operations may include disking the field, re-smoothing the soil, seedbed formation, reducing the seedbeds, and shallow cultivation for weed control. Tillage practices in conjunction with rainfall have been linked to soil erosion, which may adversely affect the environment. The soil erosion dynamics of two large-scale production cotton fields that utilized both modern-conventional and conservation-tillage technology were examined. Studies were conducted in the cotton-producing region of southeast Arkansas in the Bayou Bartholomew watershed. Bayou Bartholomew is currently listed by the United States Environmental Protection Agency as an impacted stream. The soils at these sites were related, coarse-textured alfisols. One field was cropped to conventionally tilled cotton and intensively tilled. The second field was cropped to cotton using modern conservation tillage technology. Both fields were furrow-flow irrigated using piped water. Intense rainfall usually occurs in the Mississippi River Delta Region, particularly in the winter and spring months. Conservation tillage proved to be immediately beneficial in controlling soil erosion and sediment loss due to field run-off water from rainfall. Sediment content of run-off water induced by rainfall from the conventionally tilled cotton field was significantly greater than the sediments found in run-off water from the conservation tilled cotton field. The amount of sediment found in rainfall run-off water decreased more rapidly with time under conservation tillage than under conventional tillage. The tillage system made little difference in sediment content of run-off water from irrigation. The water flow from furrow irrigation is typically slow and steady. There is no droplet impact on the ground from furrow-flow irrigation as there would be from rainfall. Apparently, the gentle flow of the water down the furrows was insufficient to dislodge large numbers of soil particles

Epithelial dynamics shed light on mechanisms underlying ear canal defects

Defects in ear canal development can cause severe hearing loss as sound waves fail to reach the middle ear. Here we reveal new mechanisms that control human canal development and highlight for the first time the complex system of canal closure and reopening. These processes can be perturbed in mutant mice and in explant culture, mimicking the defects associated with canal aplasia. The more superficial part of the canal forms from an open primary canal that closes and then reopens. In contrast, the deeper part of the canal forms from an extending solid meatal plate that opens later. Closure and fusion of the primary canal was linked to loss of periderm, with failure in periderm formation in Grhl3 mutant mice associated with premature closure of the canal. Conversely, inhibition of cell death in the periderm resulted in an arrest of closure. Once closed, re-opening of the canal occurred in a wave, triggered by terminal differentiation of the epithelium. Understanding these complex processes involved in canal development sheds light on the underlying causes of canal aplasia

Evaluation of the role of conventional and tissue doppler imaging echocardiography in detection of acute cardiac allograft rejection in heart transplant recipients

Background: Endomyocardial Biopsy (EMB) is the gold standard test for diagnosis of acute allograft cardiac rejection. Objectives: The present study aimed to assess the role of echocardiographic parameters in discriminating patients with and without evidence of acute cardiac allograft rejection. Materials and Methods: In the present cross-sectional study, using convenience sampling, 63 EMB specimens were collected from the patients who had undergone biatrial orthotropic cardiac transplantation. The mean age of the recipients and donors was 30.46 ± 9.49 and 24.55 ± 7.64 years, respectively. There were 51(81) male recipients and 39(62) male donors. Echocardiographic examination was performed within the 24 hours of EMB. The data were entered into the SPSS statistical software, version 19 and were analyzed by chi-square test, student�s t-test, and one-way ANOVA as appropriated. All the data were two-tailed and P < 0.05 was considered to be statistically significant. Results: Among the 63 EMB specimens evaluated in the present study, mild and moderate acute rejections were seen in 19(30) and 5(8) cases, respectively. On Doppler examination, the three groups (without rejection, with mild rejection, and with moderate acute rejection) were significantly different only regarding trans-tricuspid E wave (P = 0.040). Pulsed-wave Tissue Doppler Imaging (TDI) also revealed a significant difference between the patients with and without allograft rejection regarding early diastolic tricuspid and mitral annular motion velocities (P = 0.005 and P = 0.02, respectively). Conclusions: It seems that echocardiographic parameters, including TDI, might be adjunct to, rather than substitution for, EMB findings for early diagnosis of acute allograft rejection. © 2016, Iranian Cardiovascular Research Journal. All right reserved

Image authentication using LBP-based perceptual image hashing

Feature extraction is a main step in all perceptual image hashing schemes in which robust features will led to better results in perceptual robustness. Simplicity, discriminative power, computational efficiency and robustness to illumination changes are counted as distinguished properties of Local Binary Pattern features. In this paper, we investigate the use of local binary patterns for perceptual image hashing. In feature extraction, we propose to use both sign and magnitude information of local differences. So, the algorithm utilizes a combination of gradient-based and LBP-based descriptors for feature extraction. To provide security needs, two secret keys are incorporated in feature extraction and hash generation steps. Performance of the proposed hashing method is evaluated with an important application in perceptual image hashing scheme: image authentication. Experiments are conducted to show that the present method has acceptable robustness against perceptual content-preserving manipulations. Moreover, the proposed method has this capability to localize the tampering area, which is not possible in all hashing schemes

SANS (USH1G) regulates pre-mRNA splicing by mediating the intra-nuclear transfer of tri-snRNP complexes

Splicing is catalyzed by the spliceosome, a compositionally dynamic complex assembled stepwise on pre-mRNA. We reveal links between splicing machinery components and the intrinsically disordered ciliopathy protein SANS. Pathogenic mutations in SANS/USH1G lead to Usher syndrome—the most common cause of deaf-blindness. Previously, SANS was shown to function only in the cytosol and primary cilia. Here, we have uncovered molecular links between SANS and pre-mRNA splicing catalyzed by the spliceosome in the nucleus. We show that SANS is found in Cajal bodies and nuclear speckles, where it interacts with components of spliceosomal sub-complexes such as SF3B1 and the large splicing cofactor SON but also with PRPFs and snRNAs related to the tri-snRNP complex. SANS is required for the transfer of tri-snRNPs between Cajal bodies and nuclear speckles for spliceosome assembly and may also participate in snRNP recycling back to Cajal bodies. SANS depletion alters the kinetics of spliceosome assembly, leading to accumulation of complex A. SANS deficiency and USH1G pathogenic mutations affects splicing of genes related to cell proliferation and human Usher syndrome. Thus, we provide the first evidence that splicing dysregulation may participate in the pathophysiology of Usher syndrome