Split Events Research Articles

Distribution of Nanhua-Sinian rifts and proto-type basin evolution in southwestern Tarim Basin, NW China

Abstract Based on seismic data, outcrop evidence, logging data and regional aeromagnetic data, the distribution of Nanhua–Sinian rifts in the southwestern Tarim Basin was analyzed, and on the basis of restoration of lithofacies paleogeography in different periods of Neoproterozoic–Cambrian, the evolution model of the proto-type rift basin was discussed. The Neoproterozoic Rodinia supercontinent split event formed the trigeminal rift system at the edge and inside of the craton in the southwestern Tarim Basin located in the Kunlun piedmont and Maigaiti slope. The rift in Kunlun piedmont zone was distributed along the E-W direction and was the oceanic rift in the trigeminal rift system. Two decadent rifts in N-E strike developed in the Luonan and Yubei areas of Maigaiti slope, and the interior of the rifts were characterized by a composite graben-horst structure composed of multiple grabens and horsts. The Neoproterozoic–Cambrian proto-type basin evolution in the southwestern Tarim Basin can be divided into three stages: rift in the Nanhua, embryonic passive continental margin in the Sinian, and stable passive continental margin in the Cambrian. Despite the regional tectonic movements in the end of Nanhua and Sinian, the tectonic framework of the southwestern Tarim Basin had not changed significantly, the sedimentary center of Nanhua rift basin showed the characteristics of succession in the Sinian–Early Cambrian. The Nanhua rift in Kunlun piedmont evolved into a craton marginal depression during the Sinian–Early Paleozoic, while the Luonan decadent rift in the midsection of Maigaiti slope evolved into a sag inside platform in Early Cambrian, constituting the paleogeographic framework of “two paleouplifts and one sag” with the paleouplifts in east and west sides of the slope. The later evolution of the Luonan decadent rift in the midsection of the Maigaiti slope formed two sets of reservoir-forming assemblages, the Sinian and the Lower Cambrian ones, which are important exploration targets in future.

Forecasting extreme stratospheric polar vortex events

Extreme polar vortex events known as sudden stratospheric warmings can influence surface winter weather conditions, but their timing is difficult to predict. Here, we examine factors that influence their occurrence, with a focus on their timing and vertical extent. We consider the roles of the troposphere and equatorial stratosphere separately, using a split vortex event in January 2009 as the primary case study. This event cannot be reproduced by constraining wind and temperatures in the troposphere alone, even when the equatorial lower stratosphere is in the correct phase of the quasi biennial oscillation. When the flow in the equatorial upper stratosphere is also constrained, the timing and spatial evolution of the vortex event is captured remarkably well. This highlights an influence from this region previously unrecognised by the seasonal forecast community. We suggest that better representation of the flow in this region is likely to improve predictability of extreme polar vortex events and hence their associated impacts at the surface.

Differences between the 2018 and 2019 stratospheric polar vortex split events

Two recent occurrences in February 2018 and January 2019 of a dynamic split in the Northern Hemisphere stratospheric polar vortex are compared in terms of their evolution and predictability. The 2018 split vortex was associated with primarily wavenumber‐2 wave forcing that was not well predicted more than 7–10 days ahead of time, and was followed by persistent coupling to the surface with strong weather impacts. In 2019 the vortex was first displaced by slow wavenumber‐1 amplification into the stratosphere, which was predictable at longer lead times and then split; the surface impacts following the event were weaker. Here we examine the role of large‐scale climate influences, such as the phase of the El Niño–Southern Oscillation, the Quasi‐biennial Oscillation and the Madden–Julian Oscillation, on the wave forcing, surface impacts and predictability of these two events. Linkages between the forecast error in the stratospheric polar vortex winds with the forecast error in the Quasi‐biennial Oscillation and Madden–Julian Oscillation are examined.

Observations of Disintegrating Long-period Comet C/2019 Y4 (ATLAS): A Sibling of C/1844 Y1 (Great Comet)

Abstract We present a study of C/2019 Y4 (ATLAS) using Sloan gri observations from 2020 mid-January to early April. During this time span, the comet brightened with a growth in the effective cross-section of m2 s−1 from the beginning to ∼70 days preperihelion in late 2020 March, followed by a brightness fade and the comet gradually losing the central condensation. Meanwhile, the comet became progressively bluer, and was even bluer than the Sun (g − r ≈ 0.2) when the brightness peaked, likely due to activation of subterranean fresh volatiles exposed to sunlight. With the tailward bias-corrected astrometry we found an enormous radial nongravitational parameter, au day−2 in the heliocentric motion of the comet. Taking all of these findings into consideration, we conclude that the comet has disintegrated since 2020 mid-March. By no means was the split new to the comet, as we quantified that the comet had undergone another split event around last perihelion ∼5 kyr ago, during which its sibling C/1844 Y1 (Great Comet) was produced, with the in-plane component of the separation velocity ≳1 m s−1. We constrained that the nucleus of C/2019 Y4 before disintegration was ≳60 m in radius, and has been protractedly ejecting dust grains of ∼10–40 μm (assuming a dust bulk density of 0.5 g cm−3) with an ejection speed of ∼30 m s−1 in early 2020 March and increased to ∼80 m s−1 toward the end of the month for grains of ∼10 μm.

Capital Market Reaction in Indonesia Stock Exchange to Stock Split Events Reviewed From Abnormal Returns, Trading Volume and Bid-Ask Spreads in Growing and Good Speaking Companies

Capital Market Reaction in Indonesia Stock Exchange to Stock Split Events Reviewed From Abnormal Returns, Trading Volume and Bid-Ask Spreads in Growing and Good Speaking Companies

An Empirical Study on Expected Return Models with Reference to Bonus Issues and Stock Splits in Indian Share Market

This article will evaluate the Expected Return Models (ERM) in event study methodology in the Indian share market. Three main return models, namely, Market Model (MM), Market-Adjusted Model (MAAM), and Mean-Adjusted Model (MEAM) use with an intension to know the any variations in Average Abnormal Return (AAR) and Cumulative Average Abnormal Return (CAAR) on event day of the bonus issues and stock split actions. Total 240 bonus issues and 200 stock Samples are selected from SP it means that bonus issue impact on stocks changes based on different classifications. Stock Split issue events abnormal returns on event day similar in all models. Still, returns are not the same in all classifications; it means that split issue impact on stocks changes based on different classifications. It is also concluded that bonus and split events results are the same in all three expected return models but results varied in sample classifications.

Low latitude dynamical response to vortex split sudden stratospheric warming: An Eliassen Palm Flux perspective

The present work extensively describes the tropical dynamical changes during the Vortex split Major Stratospheric Warming (V-MSW) event occurred in recent decades. For better visualization of high latitude influence of tropical atmosphere, in this study, we have utilized three successive major vortex split warming events occurred in winters 1984/85, 1988/89 and 2008/09. The realistic visualization of planetary wave activity and its tropical response can be achieved by using Eliassen –Palm flux as a diagnostic tool. The investigation reveals that the tropical weather shows significant changes in temperature, convection and wind circulation during the course of vortex split major stratospheric warming.

STOCK SPLIT AND STOCK MARKET REACTION: THE EVIDENCE OF INDONESIAN PUBLIC COMPANY

Purpose of study: Go Public Company can raise funds for its operations through the sale of shares to investors. But if the stock price is too high, it can make the investors are not interested in buying stock. Stock market value can be reduced by the stock-split. This study aims to examine the effect of the stock split on abnormal return, stock price; trading volume and security return variability in the go public company on the Indonesia Stock Exchange.
 Methodology: Researchers use data from 41 companies that were taken by purposive sampling from 2013 to 2016. The hypotheses in this study were tested using a Paired sample t-test. 
 Result: The researcher found that the stock split event causes the difference between the stock price, trading volume and security return variability between before and after the stock split. But the results found that the stock split did not cause any differences between the abnormal return before and after the stock split. 
 Application: The results of this study can provide an overview of the relationship between stock split events with stock prices and stock trading volumes.
 Novelty/Originality of this study: This research using different methods compare with previous, namely multiple discriminant analysis. The multiple discriminant analysis methods are part of the discriminant analysis, which is a multivariate technique that includes the dependence method, namely the presence of variables.

PERUBAHAN TINGKAT LIKUIDITAS SAHAM DAN ABNORMAL RETURN YANG DIPENGARUHI OLEH PERISTIWA PEMECAHAN SAHAM

This study was conducted to determine the significance of changes in stock liquidity and abnormal stock returns before and after the stock split. The sample technique used in this study was purposive sampling and the criteria used included the issuer not taking other corporate actions at the same time as the stock split. The samples used in this study were 28 companies. The results of this study indicate that stock split events have a significant effect on the level of stock liquidity. Whereas for abnormal stock returns, stock splits do not affect the overall meaning, stock splits do not affect the level of abnormal stock returns

A split target detection and tracking algorithm for ballistic missile tracking during the re-entry phase

In the re-entry phase of a ballistic missile, decoys can be deployed as a mean to overburden enemy defenses. This results in a single track being split into multiple track-lets. Tracking of these track-lets is a critical task as any miss in the tracking procedure can become a cause of a major threat. The tracking process becomes more complicated in the presence of clutter. The low detection rate is one of the factors that may contribute to increasing the difficulty level in terms of tracking in the cluttered environment. This work introduces a new algorithm for the split event detection and target tracking under the framework of the joint integrated probabilistic data association (JIPDA) algorithm. The proposed algorithm is termed as split event-JIPDA (SE-JIPDA). This work establishes the mathematical foundation for the split target detection and tracking mechanism. The performance analysis is made under different simulation conditions to provide a clear insight into the merits of the proposed algorithm. The performance parameters in these simulations are the root mean square error (RMSE), confirmed true track rate (CTTR) and confirmed split true track rate (CSTTR).

Understanding of European Cold Extremes, Sudden Stratospheric Warming, and Siberian Snow Accumulation in the Winter of 2017/18

AbstractIt is unclear whether the Eurasian snow plays a role in the tropospheric driving of sudden stratospheric warming (SSW). The major SSW event of February 2018 is analyzed using reanalysis datasets. Characterized by predominant planetary waves of zonal wave 2, the SSW developed into a vortex split via wave–mean flow interaction. In the following two weeks, the downward migration of zonal-mean zonal wind anomalies was accompanied by a significant transition to the negative phase of the North Atlantic Oscillation, leading to extensive cold extremes across Europe. Here, we demonstrate that anomalous Siberian snow accumulation could have played an important role in the 2018 SSW occurrence. In the 2017/18 winter, snow depths over Siberia were much higher than normal. A lead–lag correlation analysis shows that the positive fluctuating snow depth anomalies, leading to intensified “cold domes” over eastern Siberia (i.e., in a region where the climatological upward planetary waves maximize), precede enhanced wave-2 pulses of meridional heat fluxes (100 hPa) by 7–8 days. The snow–SSW linkage over 2003–19 is further investigated, and some common traits among three split events are found. These include a time lag of about one week between the maximum anomalies of snow depth and wave-2 pulses (100 hPa), high sea level pressure favored by anomalous snowpack, and a ridge anchoring over Siberia as precursor of the splits. The role of tropospheric ridges over Alaska and the Urals in the wave-2 enhancement and the role of Arctic sea ice loss in Siberian snow accumulation are also discussed.

An Ancient Mutation in the TPH1 Gene is Consistent with the Changes in Mammalian Reproductive Rhythm.

The reproductive rhythm undergoes several changes during the evolution of mammals to adapt to local environmental changes. Although the critical roles of melatonin (MLT) in the formation of reproductive rhythm have been well established, the genetic basis for the changes of reproductive rhythm remains uncertain. Here, we constructed the phylogenetic trees of 13 melatonin synthesis, metabolism and receptor genes, estimated their divergence times, and calculated their selection pressures. Then, we evaluated the effect of positively selected and functionally related mutations on protein activity. Our results showed that there were significant positive selection sites in the three major genes, including tryptophan hydroxylase 1 (TPH1), tryptophan hydroxylase 2 (TPH2) and indoleamine-2,3-dioxygenase 1 (IDO1) that are involved in melatonin synthesis, metabolism and function. At the protein level, amino acids at the 442nd site of TPH1 protein and the 194th, 286th, 315th and 404th sites of IDO1 protein were under positive selection, and the variants of the amino acid in these sites might lead to the changes in protein function. Remarkably, the 442nd site of these positive selection sites is in the tetramerization domain of TPH1 protein, and it is proline or leucine. At this site, 89.5% of the amino acid of non-seasonal reproducing mammals was proline, while that of 88.9% of seasonal reproducing mammals was leucine. This variation of the amino acid was derived from the T/C polymorphism at the 1325th site of the TPH1 gene coding sequence, which significantly altered the TPH1 activity (p < 0.01). Interestingly, the predicted age of the allele C in the mammalian genome appeared about 126.6 million years ago, and allele T appeared about 212.6 million years ago, indicating that the evolution of the TPH1 gene was affected by the two mammalian split events and the K-T extinction event. In conclusion, the T/C polymorphism at the 1325th site in the TPH1 gene coding sequence altered TPH1 activity, suggesting that this polymorphism is consistent with the reproductive rhythm of mammals.

Split spawning increases robustness of coral larval supply and inter-reef connectivity

Many habitat-building corals undergo mass synchronous spawning events. Yet, despite the enormous amounts of larvae produced, larval dispersal from a single spawning event and the reliability of larval supply are highly dependent on vagaries of ocean currents. However, colonies from the same population will occasionally spawn over successive months. These split spawning events likely help to realign reproduction events to favourable environmental conditions. Here, we show that split spawning may benefit corals by increasing the reliability of larval supply. By modelling the dispersal of coral larvae across Australia’s Great Barrier Reef, we find that split spawning increased the diversity of sources and reliability of larval supply the reefs could receive, especially in regions with low and intrinsically variable connectivity. Such increased larval supply might help counteract the expected declines in reproductive success associated with split spawning events.

Research on Event-based Geospatial Data Updating

Abstract. How to update the geospatial data timely and accurately has become the focus of surveying and mapping. However, an efficient updating system has not been set up so far. Still the updating operations depend on human-computer interaction, which is less efficient, labour-consuming and prone to error. Accordingly, this paper proposes a new event-based updating method of geospatial data in order to improve the automation and intelligence of data updating. The main contents of the paper are as follows:On the basis of the five classical categories of spatio-temporal change typology, the paper proposes a new classification which includes create, transform, death, disappear, reappear, split，divide，combine，merge and so on. The above new classification of spatio-temporal change type is more compatible with geospatial data updating.The paper proposes a new conception about the life cycle of geospatial features which simulates spatio-temporal changing process of the geospatial entity on the world. The life cycle of geospatial features is composed of three stages: emergence, existence and death. The rules of the above life cycle of geospatial features are also set up.The paper gives a definition of geographical events and also sets up the conceptual model of geographical eventswhich is composed of time, location, geospatial feature, geographical event type and procedure. To better meet the demand of geospatial data updating, the geographical events are also reclassified into create event, transform event,death event, disappear event, reappear event, evolution event, split event, divide event, combine event and merge event.The paper suggests that homologous geographical feature matching and change detecting should be used to deduce spatio-temporal change type and extract geographical events. The thesis intends to set up an up-to-down matching pattern with four layers so as to improve the efficiency and accuracy of matching. Buffer area matching and attribute matching are used to match the point features of the same names. Both the minimum bounding rectangle overlap area and discrete Fréchet distance are used to match the line features of the same names. As for area features, feature overlapping area and Hausdorff distance are employed in matching. In addition, the thesis proposes to use XML to organize and store dynamic updating operation.Under the guidance of event-based geospatial data updating method, the related prototype system has been established and tested in the updating experiments of residence community and roads.

The Stratospheric Sudden Warming Event in February 2018 and its Prediction by a Climate System Model

AbstractA major stratospheric sudden warming (SSW) event was observed in February 2018 after a 4‐year absence since the winter of 2013/2014. Based on the reanalysis data, the polar night jet changed from a very strong state to a moderate state during 12–19 January, and the moderate westerlies directly reversed to easterlies during 5–15 February. The intensified East Asian trough, Alaskan blocking, and East U.S. trough amplified the extratropical climatological wave 2, which propagated upward into the stratosphere, leading to a vortex‐splitting SSW event. Predictions of the February 2018 SSW event are explored in hindcasts initialized 0–4 weeks in advance by the Beijing Climate Center Climate System Model. Less than 20% of the 28 ensemble members predict the reversal of [U]60°N, 10hPa in hindcasts initialized 3 or 4 weeks in advance if a 5‐day error is allowed, while this ratio increases to 43% in hindcasts initialized 1 week in advance. Based on the climatological occurrence of SSW events in the forecast system, the maximum deterministic predictable limit of this event is 1–2 weeks in this forecast system. The eddy heat flux and its domination by wave 2 can only be predicted within the predictable time limit. A comparison between hindcast members initialized 2 weeks in advance suggests that the extratropical troughs and blockings are responsible for the upward propagation of waves from the troposphere to the stratosphere. The predictable limit of the stratospheric circulation pattern for the February 2018 SSW, 1–2 weeks, also generalizes to other vortex split SSW events such as the January 2009 and February 1999 cases.

The Downward Influence of Sudden Stratospheric Warmings: Association with Tropospheric Precursors.

Tropospheric features preceding sudden stratospheric warming events (SSWs) are identified using a large compendium of events obtained from a chemistry–climate model. In agreement with recent observational studies, it is found that approximately one-third of SSWs are preceded by extreme episodes of wave activity in the lower troposphere. The relationship becomes stronger in the lower stratosphere, where ~60% of SSWs are preceded by extreme wave activity at 100 hPa. Additional analysis characterizes events that do or do not appear to subsequently impact the troposphere, referred to as downward and non-downward propagating SSWs, respectively. On average, tropospheric wave activity is larger preceding downward-propagating SSWs compared to non-downward propagating events, and associated in particular with a doubly strengthened Siberian high. Of the SSWs that were preceded by extreme lower-tropospheric wave activity, ~2/3 propagated down to the troposphere, and hence the presence of extreme lower-tropospheric wave activity can only be used probabilistically to predict a slight increase or decrease at the onset, of the likelihood of tropospheric impacts to follow. However, a large number of downward and non-downward propagating SSWs must be considered (>35), before the difference becomes statistically significant. The precursors are also robust upon comparison with composites consisting of randomly selected tropospheric northern annular mode (NAM) events. The downward influence and precursors to split and displacement events are also examined. It is found that anomalous upward wave-1 fluxes precede both cases. Splits exhibit a near instantaneous, barotropic response in the stratosphere and troposphere, while displacements have a stronger long-term influence.

Evaluation of Patients with Swallowing Difficulties by Modified Barium Swallow

Patients with swallowing difficulties are commonly encountered in the ENT OPD.Swallowing disorders can occur at any age but it is more common in the elderly patients.Neurological causes and malignancy account for the main reason in most of the cases.The modified barium swallow provides information about the complex split second events underlying the swallowing process. We can evaluate the effectiveness of swallowing manouveres by which we can prevent aspiration in patients with pharyngeal retention. AIMS 1.To study the various phases of swallowing in patients with dysphagia by modified barium swallow 2.To identify the patients with risk of aspiration during swallowing 3.To study the effectiveness of swallowing manouveres by the modified barium swallow technique Materials and methods: 200 patients who attended ear, nose, and throat out patient department with history of swallowing difficulties for more than 3 months were included in the study.Modified barium swallow was done in all these patients. Patients with risk of aspiration were detected by the amount of pharyngeal retention in the pyriform sinuses and vallecula after swallowing.The patients with grade 3 severe form of pharyngeal coating were given training for postural technique and swallowing manoeuvres to prevent aspiration. Results: Out of the 200 patients, 92 patients were found to have abnormal findings during the study. Other 108 patients had normal findings on videofluoroscopy.Out of the 92 patients with the abnormal videofluoroscopic findings,28 patients have pharyngeal retention alone with no other structural abnormalities.We focussed mainly on the patients with pharyngeal retention.16 of them were found to have grade 3 severe pharyngeal retention.These patients had history of stroke in the past.They were given training on swallowing manouveres to prevent aspiration.We found that these manouveres are effective in doing so.Another 12 patients had pharyngeal retention with no aspiration risk and they were in between the 61-80 yrs.

Statistics on Nonmigrating Diurnal Tides Generated by Tide-Planetary Wave Interaction and Their Relationship to Sudden Stratospheric Warming

The nonmigrating diurnal tide, DW2, is known to have a source from the stationary planetary wave with wavenumber 1 (SPW1) and the migrating diurnal tide (DW1) interaction. Recent research has shown that DW2 time evolution in the equatorial mesopause tracks very well with SPW1 in the polar stratosphere for the winter of 2009–2010, which contains a sudden stratospheric warming (SSW) vortex split event. This paper extends previous research and investigates the relationship between these two waves for 31 winters from 1979 to 2010 with the extended Canadian Middle Atmosphere Model (eCMAM) through correlation and composite analysis. Significant correlations are present between the two waves in 20 out of 31 winters (65%). We separate the 31 winters into four categories: SSW-displacement, SSW-split, minor-SSW, and no-SSW. Our results show that there is no significant difference among the four categories in terms of correlations between the two waves. Although SPW1 is usually stronger during a SSW-D winter, this does not warrant a stronger interaction with DW2.

The analysis of data errors in financial information databases: New evidence from the Korean financial markets

Background: As financial professionals including policy-makers tend to base decisions on research performed using large machine-readable financial databases, the accuracy of the financial data provided by database companies has a direct impact on the quality of their decisions. Objectives: The objective of this study was to examine data errors in the DataGuide and KisValue databases which are both primary sources of stock prices and return data for Korea Exchange securities in Korea. This article also discussed the methodological implications of erroneous data on monthly stock returns in empirical studies on Korean financial markets. Methods: A cross-checking technique was used in this study. Results: The results suggest that there are material discrepancies between the DataGuide and KisValue databases in monthly stock returns, most of which are attributable to the mishandling of split events and of missing values. The results also indicate that DataGuide provides a more reliable service than KisValue in terms of monthly stock returns. Conclusion: The results show that extreme monthly returns resulting from serious data errors in the DataGuide and KisValue databases may be enough to sharply change the properties of monthly stock return distributions and to over- or underestimate long-term abnormal stock returns.

Enhanced residual mean circulation during the evolution of split type sudden stratospheric warming in observations and model simulations

Residual mean circulation changes during the evolution of sudden stratospheric warming (SSW) are investigated by composite analyses of 76 major warming events identified in a present day simulation performed with a coupled ocean–troposphere–stratosphere model from 299 winters. Their dynamical signatures are compared with the 17 SSW events identified from 35 years of Era-Interim data. The main difference is that, relative frequency of simulated SSW events is smaller than that obtained from reanalysis. SSW events are classified as displacement or split events based on the geopotential field values at 10 hPa. The geopotential field values identify 10 and 3 split events in simulation and observation respectively. The model quite accurately simulates some of the dynamical features associated with the major SSW. Residual mean circulation induced by EP-flux divergence, sum of advection and residual forcing are stronger in split events than in displacement type SSW has been confirmed by both simulation and observation. Moreover, the contribution of EP-flux divergence or planetary wave forcing is larger than the contribution of other types of forcing.