Academic literature on the topic 'Timing anomalies'
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Journal articles on the topic "Timing anomalies"
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McCarthy, Joseph G., and Court B. Cutting. "The Timing of Surgical Intervention in Craniofacial Anomalies." Clinics in Plastic Surgery 17, no. 1 (January 1990): 161–82. http://dx.doi.org/10.1016/s0094-1298(20)31277-3.
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Lübbecke, Joke F., Natalie J. Burls, Chris J. C. Reason, and Michael J. McPhaden. "Variability in the South Atlantic Anticyclone and the Atlantic Niño Mode*." Journal of Climate 27, no. 21 (October 24, 2014): 8135–50. http://dx.doi.org/10.1175/jcli-d-14-00202.1.
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Abstract Previous studies have argued that the strength of the South Atlantic subtropical high pressure system, referred to as the South Atlantic anticyclone (SAA), modulates sea surface temperature (SST) anomalies in the eastern equatorial Atlantic. Using ocean and atmosphere reanalysis products, it is shown here that the strength of the SAA from February to May impacts the timing of the cold tongue onset and the intensity of its development in the eastern equatorial Atlantic via anomalous tropical wind power. This modulation in the timing and amplitude of seasonal cold tongue development manifests itself via SST anomalies peaking between June and August. The timing and impact of this connection is not completely symmetric for warm and cold events. For cold events, an anomalously strong SAA in February and March leads to positive wind power anomalies from February to June resulting in an early cold tongue onset and subsequent cold SST anomalies in June and July. For warm events, the anomalously weak SAA persists until May, generating negative wind power anomalies that lead to a late cold tongue onset as well as a suppression of the cold tongue development and associated warm SST anomalies. Mechanisms by which SAA-induced wind power variations south of the equator influence eastern equatorial Atlantic SST are discussed, including ocean adjustment via Rossby and Kelvin wave propagation, meridional advection, and local intraseasonal wind variations.
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Arora, Rohit, Deepak Bagga, and Sugandha Arya. "Surgical Corrections: Correct Timing." Journal of Neonatology 21, no. 4 (December 2007): 255–58. http://dx.doi.org/10.1177/097321790702100410.
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Many congenital anomalies amenable to surgery, while not incompatible with life may seriously hamper the growth and development of the infant if allowed to remain uncorrected. Knowledge of optimal age for correction of the lesions is of great value to the physician, since needless premature surgical referrals and prolongation beyond the optimal time may be avoided. This article brings forward few of the important surgical conditions commonly encountered in neonatal and pediatric practice and briefly reviews the optimal age for their surgical correction.
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Lawson, Daniel T., Robert L. Schwartz, and Seth D. Thomas. "Hedge Funds, Arbitrage, and Timing." International Journal of Economics and Finance 13, no. 1 (December 10, 2020): 45. http://dx.doi.org/10.5539/ijef.v13n1p45.
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This paper is an extension of the work of Lawson and Schwartz (2018) which analyzes the risk-adjusted performance of hedge funds by employing a collection of four, five, seven, and eight-factor models. The purpose is to evaluate how well the top and bottom performing subset of hedge fund strategies have profited on known asset pricing anomalies during two unique time periods, 1994 to 2000 and 2001 to 2008. The bifurcation of the data into two distinct periods allows for a deeper exploration of the potential time-varying significance of estimated factor arbitrage. Our empirical testing suggests that both the top and bottom performing funds did utilize the asset growth anomaly to generate abnormal profits. Top performers tended to invest with a long emphasis on low asset growth, value firms while the bottom-five performing hedge fund strategies tested positive for a predilection towards going long small firms with low asset growth characteristics. Arguably, these outcomes probably align with the nature of the investment philosophy of each fund strategy. Interestingly, however, the time-varying significance of estimated coefficients for the value and returns momentum factors between the two distinct timeframes suggests either intentional or unintentional rotation between the use of available pricing anomalies and risk premiums.
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Nagorneva, Stanislava V., Victoria S. Prokhorova, Elizaveta V. Shelaeva, and Alexandra M. Khudovecova. "The prevalence of congenital fetal anomalies for the past 5 years (2013-2017)." Journal of obstetrics and women's diseases 67, no. 3 (December 15, 2018): 44–48. http://dx.doi.org/10.17816/jowd67344-48.
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This article presents the data on the prevalence of congenital fetal anomalies in our hospital population obtained for the past five years (2013–2017). We analyzed the changes in their structure and the timing of diagnoses for the anomalies. In addition, the comparison of our results with international data was performed and extremely rare anomalies were described.
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Zakeri, Mohammadreza. "Pulsar timing anomalies: a window into baryon number violation." Journal of Cosmology and Astroparticle Physics 2024, no. 05 (May 1, 2024): 052. http://dx.doi.org/10.1088/1475-7516/2024/05/052.
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Abstract We investigate the influence of a specific class of slow Baryon Number Violation (BNV)—one that induces quasi-equilibrium evolution — on pulsar spin characteristics. This work reveals how BNV can potentially alter observable parameters, including spin-down rates, the second derivative of spin frequency, and braking indices of pulsars. Moreover, we demonstrate that BNV could lead to anomalies in pulsar timing, along with a wide array of braking indices, both positive and negative. In addition, we examine the possibility of pulsar spin-up due to BNV, which may result in a novel mechanism for the revival of “dead” pulsars. We conclude by assessing the sensitivity required for future pulsar timing efforts to detect such BNV effects, thus highlighting the potential for pulsars to serve as laboratories for testing fundamental physics.
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Ferguson, Ian M., John A. Dracup, Philip B. Duffy, Philip Pegion, and Siegfried Schubert. "Influence of SST Forcing on Stochastic Characteristics of Simulated Precipitation and Drought." Journal of Hydrometeorology 11, no. 3 (June 1, 2010): 754–69. http://dx.doi.org/10.1175/2009jhm1132.1.
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Abstract Recent studies demonstrate that ocean–atmosphere forcing by persistent sea surface temperature (SST) anomalies is a primary driver of seasonal-to-interannual hydroclimatic variability, including drought events. Other studies, however, conclude that although SST anomalies influence the timing of drought events, their duration and magnitude over continental regions is largely governed by land–atmosphere feedbacks. Here the authors evaluate the direct influence of SST anomalies on the stochastic characteristics of precipitation and drought in two ensembles of AGCM simulations forced with observed (interannually varying) monthly SST and their climatological annual cycle, respectively. Results demonstrate that ocean–atmosphere forcing contributes to the magnitude and persistence of simulated seasonal precipitation anomalies throughout the tropics but over few mid- and high-latitude regions. Significant autocorrelation of simulated seasonal anomalies over oceans is directly forced by persistent SST anomalies; over land, SST anomalies are shown to enhance autocorrelation associated with land–atmosphere feedbacks. SST anomalies are shown to have no significant influence on simulated drought frequency, duration, or magnitude over most midlatitude land regions. Results suggest that severe and sustained drought events may occur in the absence of persistent SST forcing and support recent conclusions that ocean–atmosphere forcing primarily influences the timing of drought events, while duration and magnitude are governed by other mechanisms such as land–atmosphere feedbacks. Further analysis is needed to assess the potential model dependence of results and to quantify the relative contribution of land–atmosphere feedbacks to the long-term stochastic characteristics of precipitation and drought.
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Pattar, Pratima Manohar, Sainath K. Andola, Asha Patil, and Suraj B. "Frequency of Urinary Anomalies in Perinatal Autopsies." Indian Journal of Forensic Medicine and Pathology 14, no. 3 (September 15, 2021): 347–54. http://dx.doi.org/10.21088/ijfmp.0974.3383.14321.4.
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Background: Congenital anomalies of urinary system are common and are found in 3-4% of population, and 10% of terminations of pregnancies are attributable to lethal urinary anomalies. Although timely detection of nonlethal anomalies depends on many aspects, for instance equipment quality, sonologist experience and timing of the ultrasound examination. However, to confirm the findings and to attain definite diagnosis, a fetal autopsy after the termination of a pregnancy is of utmost important and is also crucial for genetic counseling.In view of this, the present study aimed to determine the frequency and to identify the types of the urinary anomalies in perinatal autopsies. Methods: This study includes 391 perinatal autopsies conducted prospectively from July 2016 to June 2018 at M. R. Medical College, Basaveshwar Teaching and General Hospital, Kalaburagi. After obtaining the consent from either parent, each fetus was examined as per the predetermined protocol which included ultrasound diagnosis, photographs, external and internal examination. Results: The gestational age ranged from 16weeks to 44weeks and the mean weight was 1123.96gm. Out of 391 cases urinary anomalies encountered in 19 cases )4.9%). Out of 19 cases, anomalies of renal parenchyma were seen in 15 cases )78.9%) and anomalies of pelvi-ureters and bladder was seen in 4 cases )21.1%). Three cases of urinary anomalies were associated with syndromes and 8 cases were associated with other system anomalies. Conclusion: The perinatal autopsy after termination of pregnancy is essential to confirm the ultrasound findings and to make a definitive diagnosis.
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Friedel, Marina, Gabriel Chiodo, Andrea Stenke, Daniela I. V. Domeisen, and Thomas Peter. "Effects of Arctic ozone on the stratospheric spring onset and its surface impact." Atmospheric Chemistry and Physics 22, no. 21 (November 2, 2022): 13997–4017. http://dx.doi.org/10.5194/acp-22-13997-2022.
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Abstract. Ozone in the Arctic stratosphere is subject to large interannual variability, driven by both chemical ozone depletion and dynamical variability. Anomalies in Arctic stratospheric ozone become particularly important in spring, when returning sunlight allows them to alter stratospheric temperatures via shortwave heating, thus modifying atmospheric dynamics. At the same time, the stratospheric circulation undergoes a transition in spring with the final stratospheric warming (FSW), which marks the end of winter. A causal link between stratospheric ozone anomalies and FSWs is plausible and might increase the predictability of stratospheric and tropospheric responses on sub-seasonal to seasonal timescales. However, it remains to be fully understood how ozone influences the timing and evolution of the springtime vortex breakdown. Here, we contrast results from chemistry climate models with and without interactive ozone chemistry to quantify the impact of ozone anomalies on the timing of the FSW and its effects on surface climate. We find that ozone feedbacks increase the variability in the timing of the FSW, especially in the lower stratosphere. In ozone-deficient springs, a persistent strong polar vortex and a delayed FSW in the lower stratosphere are partly due to the lack of heating by ozone in that region. High-ozone anomalies, on the other hand, result in additional shortwave heating in the lower stratosphere, where the FSW therefore occurs earlier. We further show that FSWs in high-ozone springs are predominantly followed by a negative phase of the Arctic Oscillation (AO) with positive sea level pressure anomalies over the Arctic and cold anomalies over Eurasia and Europe. These conditions are to a significant extent (at least 50 %) driven by ozone. In contrast, FSWs in low-ozone springs are not associated with a discernible surface climate response. These results highlight the importance of ozone–circulation coupling in the climate system and the potential value of interactive ozone chemistry for sub-seasonal to seasonal predictability.
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Bhatia, Parul, Sudhi Sharma, Vaibhav Aggarwal, and Niyati Chaudhary. "Testing event-based day of the week anomaly and trading opportunities: Evidence from Indian sectoral indices." Investment Management and Financial Innovations 21, no. 2 (April 8, 2024): 28–43. http://dx.doi.org/10.21511/imfi.21(2).2024.03.
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The study is an attempt to examine the day-of-the-week anomaly of fourteen Indian sectoral indices and identify profitable opportunities, considering multiple positive and negative events. The aim of this study is to analyze the day-of-the-week effect on fourteen Indian sectoral indices and find profitable opportunities while considering multiple events that have positive and negative impacts. The study takes into consideration event-based anomalies, both national and global, and provides timing for trading to generate abnormal returns from the market. At first, dummy variable regression analysis was used to understand the initial anomalies. Later, time-varying symmetrical and asymmetrical volatility models, such as Generalized Autoregressive Conditional Heteroscedasticity (1, 1) and Exponential Generalized Autoregressive Conditional Heteroscedasticity (1, 1) were applied to determine the short-term and long-term volatility persistence. These models capture the leverage effect from various events that occurred during the study. The results showed mixed outcomes during multiple positive and negative shocks. After the recession, anomalies were observed across all sectoral indices, except for commodities, energy, and information technology. During the scam period, anomalies occurred in all sectors, except for consumer durables, financial services, and information technology. However, after the new government took over, anomalies persisted in all sectors. During the pandemic, anomalies persisted in all sectors except for finance, IT, pharmaceuticals, and services. Hence, national and global events have shown varied impacts on the Indian markets. The study provides investors with implications on strategies and timing techniques for planning their investments in different sectors of the Indian economy.
Dissertations / Theses on the topic "Timing anomalies"
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Gebhard, Gernot [Verfasser], and Reinhard [Akademischer Betreuer] Wilhelm. "Static timing analysis tool validation in the presence of timing anomalies / Gernot Gebhard. Betreuer: Reinhard Wilhelm." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2013. http://d-nb.info/1053679947/34.
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Sithirasenan, Elankayer. "Substantiating Anomalies in Wireless Networks Using Outlier Detection Techniques." Thesis, Griffith University, 2009. http://hdl.handle.net/10072/365690.
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With the increasing dependence on Wireless Local Area Networks (WLANs), businesses
and educational institutions are in real need of a robust security mechanism.
The latest WLAN security protocol, the IEEE 802.11i assures rigid security for
wireless networks with the support of IEEE 802.1x protocol for authentication,
authorization and key distribution. Nevertheless, users remain skeptical since they
lack confidence on the practical trustworthiness of these security mechanisms. In
this research we propose a novel Early Warning System (EWS), built on the foundations
of IEEE 802.11i security architecture. Our proposed system can effectively
detect anomalies, substantiate them, and also identify the basis for such malicious
behavior. It has a number of levels of defense to scrutinize malicious behaviors
of the wireless network, caused by a range of factors including security issues.
Security alerts will be raised only when the legitimacy of abnormal conditions is
validated using effective outlier based substantiation techniques.
Timing anomalies can occur due to various conditions including security vulnerabilities
in the wireless environment. Hence, detecting and analyzing such
anomalies may lead to significant advancement towards the detection of misbehaving
wireless hosts. In this view, we have discussed the effectiveness of monitoring
and analyzing round trip timing values between every request and response
messages during the authentication process of wireless hosts. Further, to enhance
the capabilities of our detection mechanism we have also considered the effect
of behavioral anomalies of the wireless hosts. Every wireless host that tends to
connect to the wireless network exhibits a particular behavior. This behavior may vary depending on a number of issues including security vulnerabilities. Hence,
in this study we have discussed the use of behavioral analysis for detecting abnormal
conditions. We have used the standard theoretical/practical behavior profiles
developed using a software model of the wireless hosts to compare the actual
behavior during a specific authentication process.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Information and Communication Technology
Science, Environment, Engineering and Technology
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Bradshaw, Steve. "Style anomalies on the London Stock Exchange : an analysis of univariate, multivariate and timing strategies." Thesis, University of Cape Town, 2005. http://hdl.handle.net/11427/6691.
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According to Dimson (1998), modem financial theory is founded on the assumption that markets are highly efficient. The presence of anomalous stock market behaviour has therefore attracted a great amount of research internationally. This thesis investigates the presence and exploitability of style anomalies on the London Stock Exchange (LSE) and is divided into three main branches of research.
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Dunn, Bryan. "Style anomalies on the Toronto Stock Exchange : a univariate, multivariate, style timing and portfolio sorting analysis." Master's thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/10429.
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Includes bibliographical references.A growing body of empirical evidence has found inconsistencies in the Capital Asset-pricing Model (CAPM) of Sharpe (1964), Lintner (1965), and Black (1972) and Ross's (1976) Arbitrage Pricing Theory (APT). Numerous attempts to explore the validity of these theories of modern finance have led to the identification of various firm specific attributes that explain the cross-sectional variation of returns. These attributes have appropriately been termed 'style anomalies '.This thesis investigates the existence and exploitability of style anomalies for the shares comprising the Toronto Stock Exchange (TSX) for the period 31 January 1989 to 31 July 2005. The investigation is divided into four areas of research. First, a methodology similar to Fama and Macbeth (1973) is used to explore the cross-sectional relationships between some 904 firm-specific attributes and the unadjusted and risk adjusted monthly returns of equities constituting the S&P TSX Composite Index. A myriad of uncorrelated style anomalies are found to persist before and after controlling for systematic risk, and are categorized as either size, growth, momentum, value, liquidity and bankruptcy (risk) effects. The most significant attributes from each respective style group include: Price, eighteen month change in net tangible asset value, price change over twelve months, twelve month change in price to net tangible asset value, three month change in the absolute volume ratio and interest cover before tax. Multivariate testing confirms the ability of anomalies to explain excess returns. In and out sample cross sectional tests show inconsistent anomaly persistence, raising the question of whether they are perhaps perennial in nature. Second, the predictability of style payoffs is examined through the analysis of autocorrelation and six style timing models. Strong positive autocorrelation at lower orders for the majority of style payoffs suggests that the ability to time payoffs is possible. The six month moving average timing model shows the best forecasting skill, followed by twelve month and eighteen month moving average models. Third, the presence of firm specific attributes among three classified sectors namely: Basic materials, Cyclicals and Non-Cyclicals are compared. Risk, value and liquidity based anomalies dominate the Basic Materials shares. Liquidity effects stand out within the Cyclicals group, and the Non-Cyclicals sectors exhibit value and size effects. The ability to exploit all style-based anomalies after accounting for transaction costs is evaluated using a portfolio sorting methodology. The tests illustrate that increased exposure to the anomalies has delivered substantially higher returns with lower volatility than a buy and hold approach using an equally weighted all share benchmark. These abnormal returns are confirmed after adjusting for systematic risk. Further testing shows that the attributes, rather than loading on those attributes, are better at explaining share returns. Finally, the seasonal nature of Canadian equity returns is investigated. A six month strategy of "Selling in June and going away till December" provides the most optimal returns. The calendar month tests find January, February and December to be the strongest months of the year. Attribute payoffs seem to show vague seasonal tendencies.
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Binder, Benjamin. "Definitions and Detection Procedures of Timing Anomalies for the Formal Verification of Predictability in Real-Time Systems." Electronic Thesis or Diss., université Paris-Saclay, 2022. http://www.theses.fr/2022UPASG086.
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Les systèmes temps-réel sont souvent validés par des analyses temporelles, qui sont mises en péril par des anomalies temporelles (AT). Une AT contre-intuitive a lieu quand une accélération locale conduit à un ralentissement global, et une AT d'amplification, quand un ralentissement local entraîne un ralentissement encore plus grand.Alors que les AT contre-intuitives menacent le bien-fondé ou la flexibilité des analyses, il n'existe pas d'outils pour les détecter de manière systématique. Nous proposons une structure formelle unifiée pour évaluer les définitions des AT, concluant au manque d'une définition pratique, principalement dû à l'absence de relations entre les effets temporels locaux et globaux. Nous y répondons par la causalité, que nous utilisons pour revoir la formalisation de ces AT. Nous proposons aussi une instance des notions spécialisée pour les pipelines out-of-order. Nous évaluons notre procédure de détection subséquente sur des exemples illustratifs et bancs de tests, montrant qu'elle permet de capturer précisément les AT.La complexité des systèmes exige que leurs analyses gèrent l'important espace d'états résultant. Une solution est de réaliser des analyses compositionnelles, précisément menacées par les AT d'amplification. Nous faisons progresser leur étude en montrant comment une abstraction spécialisée peut être adaptée pour un processeur industriel, en modélisant les caractéristiques temporelles clés avec des réductions appropriées. Nous illustrons aussi à partir de cette classe d'AT comment des stratégies de vérification peuvent être utilisées en vue de l'obtention de motifs d'ATThe timing behavior of real-time systems is often validated through timing analyses, which are yet jeopardized by execution phenomena called timing anomalies (TAs). A counter-intuitive TA manifests when a local speedup eventually leads to a global slowdown, and an amplification TA, when a local slowdown leads to an even larger global slowdown.While counter-intuitive TAs threaten the soundness/scalability of timing analyses, tools to systematically detect them do not exist. We set up a unified formal framework for systematically assessing the definitions of TAs, concluding the lack of a practical definition, mainly due to the absence of relations between local and global timing effects. We address these relations through the causality, which we further use to revise the formalization of these TAs. We also propose a specialized instance of the notions for out-of-order pipelines. We evaluate our subsequent detection procedure on illustrative examples and standard benchmarks, showing that it allows accurately capturing TAs.The complexity of the systems demands that their timing analyses be able to cope with the large resulting state space. A solution is to perform compositional analyses, specifically threatened by amplification TAs. We advance their study by showing how a specialized abstraction can be adapted for an industrial processor, by modeling the timing-relevant features of such a hardware with appropriate reductions. We also illustrate from this class of TAs how verification strategies can be used towards the obtainment of TA patterns
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Adkins, Sally. "Impact of Atlantic and Pacific sea surface temperature anomalies on the magnitude and timing of annual floods in northern Florida." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0004941.
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Albano, Alessandra. "Spectral and timing properties of transient anomalous x-ray pulsars." Doctoral thesis, Università degli studi di Padova, 2010. http://hdl.handle.net/11577/3427009.
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In the last years, thanks to new generation satellites (mostly Chandra and XMM-Newton), an increasing number of high resolution spectral and timing observations of X-ray emitting isolated neutron stars (INS)has become available.
Several new classes of X-ray emitting INSs have been discovered, all of them radio silent or with radio properties much at variance with those of Pulsar Radio (PSRs): X-ray Dim Isolated Neutron Stars (XDINSs), Anomalous X-ray Pulsars (AXPs) and Soft Gamma-ray Repeaters (SGRs), Central Compact Objects (CCOs), Rotating Radio Transient (RRATs, in one case).
AXPs and SGRs represent two peculiar groups of INSs, totalling 15 objects (6 SGRs and 9 AXPs plus one candidate). Although much less noumerous than PSRs, these objects have been extensively studied because of their peculiar and extreme properties.
SGRs exhibit bursts and flares with intensity between $\sim 10^2$ and $\sim 10^{11}$ times their quiescent X-ray luminosity ($10^{34} - 10^{36} \ {\rm erg/s})$. In the last decade transient phenomena have been observed from few AXPs, with luminosity increases between few 10 and few 100 times the X-ray quiescent values. The many similarities in the timing and spectral properties among SGRs and AXPs led to the suggestion that they could be two different manifestations of the same phenomenon.
These objects are believed to host a Magnetar, an ultra-magnetized neutron star with magnetic field $\sim 10^{14}-10^{15}$ G. In the Magnetar model emission from SGRs and AXPs comes to the expanse of the ultra strong magnetic field rather than of the rotational, gravitational or thermal energy. In Magnetars the external magnetic field can acquire a toroidal component as a consequence of the deformation of the star crust induced by the super-strong internal field. As a result the star magnetosphere twists up and the currents required to support the non-potential field may provide a large enough optical depth to resonant cyclotron scattering (RCS).
As a consequence a distortion in the thermal spectra emitting by the star surface is expected, because primary photons gain energy in the repeated scattering with the magnetospheric charges.
Spectra emerging from a twisted magnetosphere in presence of RCS has been investigated by several authors (Lyutikov and Gavriil, 2006, Fernandez and Thompson, 2007, Nobili Turolla and Zane, 2008) and applied to SGRs and AXPs spectra by Rea et al. 2008 and Zane et al., 2008.
The NTZ model 3D montecarlo simulation is the more advanced tool to compute both lightcurves and spectra. Resulting spectra are described in terms of 5 parameters: the twist angle $\Delta \phi$, the
electron bulk velocity $\beta$, the surface temperature $T$ and the two geometrical angles$\xi$ and $\chi$($\xi$ is the misalignement between spin and magnetic axis while $\chi$ is the line of sight inclination with respect to the spin axis).
In this thesis the application of NTZ model to two Transient AXPs XTE J1810-197 and CXOU J164710.2-455216 is discussed. XTE J1810-197 exhibited an outburst in late 2002 - early 2003, increasing its luminosity by two orders of magnitude. After the outburst onset the source has been monitored by XMM-Newton between September 2003 and September 2007, showing a decrease in flux until the pre-outburst value has been reached.
CXOU J164710.2-455216 exhibited an outburst on 21 September 2006, when it was observed at a luminosity 300 times greater than that measured just five days before. The source has been observed by XMM-Newton 6 times after the outburst onset, between September 2006 and August 2009.
In this work, adapted from Albano et al., 2010 paper, a comprehensive study of the pulse profile and spectral evolution of the two TAXPs
following their outbursts onsets is presented. By confronting timing data with synthetic lightcurves obtained from the twisted magnetosphere model (Nobili, Turolla and Zane, 2008), we were able to estimate how the physical parameters of the source (surface temperature and emitting area, electron energy, twist angle) evolve in time.
The fits of the pulse profiles also allowed us to infer the geometry of the two systems, i.e. the angles between the magnetic and rotational axes and the line of sight. Spectral models, obtained with the parameter values derived for the timing analysis, provide acceptable fits to XMM-Newton data.Negli ultimi anni, grazie alla nuova generazione di satelliti (in particolare Chandra e XMM-Newton), è divenuto possibile osservare, con alta risoluzione, un crescente numero di stelle di neutroni isolate (INSs) che emettono raggi X. Molte nuove classi di INSs che emettono raggi X sono state scoperte, nessuna delle quali emette nel radio, o con proprietà nel radio in disaccordo con quelle delle PSRs: X-ray Dim Isolated Neutron Stars (XDINSs), Anomalous X-ray Pulsars (AXPs) e Soft Gamma-ray Repeaters (SGRs), Central Compact Objects (CCOs), Rotating Radio Transient (RRATs, in un caso). AXPs e SGRs sono due gruppi di INSs con caratteristiche peculiari, formati in tutto da 15 oggetti (6 SGRs e 9 AXPs più una candidata). Anche se meno numerose delle PSRs, questi oggetti sono stati ampiamente studiati proprio in virtù delle loro proprietà peculiari ed estreme. Gli SGRs mostrano bursts e flares con intensità tra le $\sim 10^2$ e le $\sim 10^{11}$ volte la loro luminosit\`a quiescente in banda X ($10^{34} - 10^{36} \ {\rm erg/s}$). Nell'ultima decade fenomeni spettrali transienti sono stati osservati in alcune AXPs, con un aumento di luminosità compreso tra alcune decine e alcune centinaia di volte la luminosità di quiescenza. Le molte similarità nelle proprietà spettrali e di timing di SGRs e AXPs portano a suggerire che questi oggetti possano essere nient'altro che differenti manifestazioni dello stesso fenomeno. Si ritiene che queste sorgenti ospitino una Magnetar, una stella di neutroni ultra magnetizzata con campo magnetico pari a $\sim 10^{14}-10^{15}$ G. Nel modello Magnetar l'emissione da SGRs e AXPs proviene dall'espansione del campo magnetico ultra intenso piuttosto che ad energie di tipo rotazionale, gravitazionale o termico. Nelle Magnetars il campo magnetico esterno potrebbe acquisire una componente di tipo toroidale, come conseguenza della deformazione della crosta della stella indotta dall'intensissimo campo magnetico interno. Il risultato netto è un twist della magnetosfera della stella; inoltre le correnti richieste per supportare il campo non potenziale potrebbero dar luogo ad una profondità ottica sufficientemente spessa per il resonant cyclotron scattering (RCS). Di conseguenza ci si aspetta una distorsione negli spettri termici, dato che i fotoni primari guadagnano energia nei ripetuti urti con le particelle cariche presenti nella magnetosfera. Gli spettri all'uscita della magnetosfera twistata in presenza di RCS sono stati studiati da svariati autori (Lyutikov e Gavriil, 2006, Fernandez e Thompson, 2007, Nobili Turolla e Zane, 2008) e questo modello è stato applicato agli spettri di SGRs e AXPs da Rea et al. 2008 and Zane et al., 2008. Il codice montecarlo 3D creato da Nobili, Turolla e Zane (2008) è lo strumento più avanzato per calcolare curve di luce e spettri. Gli spettri così ottenuti possono essere descritti in termini di 5 parametri: l'angolo di twist $\Delta \phi$, la velocità di bulk degli elettroni $\beta$, la temperatura superficiale $T$ e i due angoli geometrici $\chi$ e $\xi$ ($\xi$ è il disassamento tra campo magnetico e asse di rotazione mentre $\chi$ è l'inclinazione della linea di vista rispetto all'asse di rotazione). In questo lavoro, riadattato dall'articolo Albano et al., 2010, viene presentato un ampio studio dei profili pulsati e dell'evoluzione spettrale delle due TAXPs a partire dall'inizio dell'outburst. Confrontando i dati di timing con le curve di luce sintentiche ottenute con il modello di magnetosfera twistata (Nobili, Turolla e Zane, 2008) siamo stati in grado di stimare l'evoluzione temporale del parametri fisici della sorgente (temperatura superficiale e area emittente, energia degli elettroni, angolo di twist). I fit del profilo pulsato ci permettono anche di asserire la eometria del sistema, e cioè l'angolo fra campo magnetico e asse di rotazione e quello tra asse di rotazione e linea di vista. I modelli spettrali, ottenuti dai valori dei parametri derivati dall'analisi di timing, danno dei fit accettabili dei dati di XMM-Newton.
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Ait, Bensaid Samira. "Formal Semantics of Hardware Compilation Framework." Electronic Thesis or Diss., université Paris-Saclay, 2023. http://www.theses.fr/2023UPASG085.
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Les analyses statiques de pire temps d’exécution sont utilisées pour garantir les délais requis pour les systèmes critiques. Afin d’estimer des bornes précises sur ces temps d’exécution, ces analyses temporelles nécessitent des considérations sur la (micro)- architecture. Habituellement, ces modèles de micro-architecture sont construits à la main à partir des manuels des processeurs. Cependant, les initiatives du matériel libre et les langages de description de matériel de haut niveau (HCLs), permettent de réaborder la problématique de la génération automatique de ces modèles de micro-architecture, et plus spécifiquement des modèles de pipeline. Nous proposons un workflow qui vise à construire automatiquement des modèles de chemin de données de pipeline à partir de conceptions de processeurs décrites dans des langages de contruction de matériel (HCLs). Notre workflow est basé sur la chaine de compilation matériel Chisel/FIRRTL. Nous construisons au niveau de la représentation intermédiaire les modèles de pipeline du chemin de données. Notre travail vise à appliquer ces modèles pour prouver des propriétés liées à la prédictibilité temporelle. Notre méthode repose sur la vérification formelle. Les modèles générés sont ensuite traduits en modèles formels et intégrés dans une procédure existante basée sur la vérification de modèles pour détecter les anomalies de temps. Nous utilisons le langage de modélisation et de vérification TLA+ et expérimentons notre analyse avec plusieurs processeurs RISC-V open-source. Enfin, nous faisons progresser les études en évaluant l’impact de la génération automatique à l’aide d’une série de critères synthétiquesStatic worst-case timing analyses are used to ensure the timing deadlines required for safety-critical systems. In order to derive accurate bounds, these timing analyses require precise (micro-)architecture considerations. Usually, such micro-architecture models are constructed by hand from processor manuals.However, with the open-source hardware initiatives and high-level Hardware Description Languages (HCLs), the automatic generation of these micro-architecture models and, more specifically, the pipeline models are promoted. We propose a workflow that aims to automatically construct pipeline datapath models from processor designs described in HCLs. Our workflow is based on the Chisel/FIRRTL Hardware Compiler Framework. We build at the intermediate representation level the datapath pipeline models. Our work intends to prove the timing properties, such as the timing predictability-related properties. We rely on the formal verification as our method. The generated models are then translated into formal models and integrated into an existing model checking-based procedure for detecting timing anomalies. We use TLA+ modeling and verification language and experiment with our analysis with several open-source RISC-V processors. Finally, we advance the studies by evaluating the impact of automatic generation through a series of synthetic benchmarks
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Sasmaz, Mus Sinem. "X-ray And Timing Properties Of Anomalous X-ray Pulsar 1e 2259+586." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/3/12608625/index.pdf.
Full textAbstract:
In this thesis, we present the spectral and timing variabilities of anomalous X-ray pulsar 1E 2259+586 observed with European Photon Imaging PN Camera (EPIC PN) on board X-ray Multi Mirror Mission (XMM), Proportional Counter Array (PCA) on board Rossi X-ray Timing Explorer (RXTE) and Advanced CCD Imaging Spectrometer (ACIS) on board Chandra X-ray Observatory.
We presented the results of spectral analysis of 2000 January 11 ACIS observation. Pulse phase spectroscopy was performed on two XMM observations before and after the outburst. Pulse profiles of two XMM observations before the outburst and three XMM observations after the outburst were studied. Results are consistent with the those presented by Patel et al. (2001) and Woods et al. (2004).
We searched for the spectral variations versus spin rate during the outburst. Long-term spectral, frequency and spin-down rate variations are presented between 1996 and 2006 including 98 RXTE and 4 XMM observations. However, except outburst region (Woods et al. 2004) no significant spectral and spin rate variabilities were seen. Around the outburst region we confirmed the spectral hardening with increasing spin rate and flux.
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PIGAZZINI, SIMONE. "Search for anomalous production of high energy photon events with the CMS detector at the LHC and prospects for HL-LHC." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2018. http://hdl.handle.net/10281/198972.
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Sebbene lo Standard Model (SM) descriva con grande successo le interazioni fondamentali della materia, esso
non fornisce la risposta a diverse domande ancora aperte nella fisica
fondamentale tra cui la natura della materia oscura, il problema della gerarchia delle
interazioni fondamentali e non fornisce un modello quantistico della gravitazione.
Per questo motivo diversi modelli mirano a completare lo SM (modelli con extra dimensioni,
modelli super-simmetrici, ...). Denominatore comune di questi modelli (denominati
generalmente BSM) è la predizione dell'esistenza di nuove particelle di massa dell'ordine
di 1 TeV. La ricerca di produzione di risonante di bosoni o fermioni nelle collisioni
protone-protone a LHC è una verifica diretta di questi modelli.
La produzione risonante di coppie di fotoni può sondare l'esistenza di
bosoni di spin-0, spin-2. L'eccellente risoluzione
che è possibile raggiungere sulla misura della massa invariante dei due fotoni, e la segnatura
peculiare del processo, permettono di cercare un picco di segnale nello spettro
di massa continuo prodotto da processi descritti dallo SM.
La risoluzione sulla massa invariante del sistema dei due fotoni è determinata da due
fattori: la risoluzione energetica sui singoli fotoni e l'efficienza nella ricostruzione
del corretto vertice di interazione da cui originano i fotoni.
La ricerca è stata condotta sui dati raccolti in collisioni protone-protone a 13 TeV effettuate
da LHC durante il 2016 (luminosità integrata pari a 35.9fb$^{-1}$).
L'aumento dell'energia disponibile nel centro di massa della collisione ha permesso
di esplorare una regione dello spettro più ampia di quella analizzata nelle
ricerca in collisioni a 8TeV raccolti nel periodo 2011-2012.
I risultati ottenuti non hanno evidenziato nessuna deviazione rispetto alla previsione del SM.
Sono stati quindi fissati dei limiti di esclusione sulle sezioni d'urto per
la produzione di gravitoni del tipo previsto dai modelli Randall-Sudrum
I limiti variano tra tra 10fb e 1fb a
seconda della massa prevista nell'intervallo $0.5 \mbox{TeV} < m < 4 \mbox{TeV}$.
I risultati sono compatibili con le osservazioni dell'esperimento ATLAS.
Il programma di LHC prevede una fase ad alta luminosità che inizierà nel 2026
durante la quale il complesso di acceleratori del CERN verrà migliorato fino a raggiungere una luminosità
istantanea di $7.5\times10^{34}\mbox{cm}^{-2}\mbox{s}^{-1}$, cinque volte maggiore rispetto a quella raggiunta
attualmente. A questo rinnovamento degli acceleratori sarà associata una revisione degli
esperimenti che prevede il miglioramento dei rivelatori
già esistenti e l'installazione di nuovi.
Ai benefici indotti dall'aumento del numero di eventi disponibili per le analisi si oppone
un generale degredamento della ricostruzione a causa dell'alto numero di collisioni che avverranno
simultaneamente. Per mitigare questo fenomeno e per massimizzare l'accettanza ai canali di interesse
per le misure di fisica CMS sta programmando un serie di interventi al rivelatore.
Tra questi l'introduzione della misura di tempo nella ricostruzione richiede la costruzione ed
installazione di un rivelatore di particelle cariche con risoluzione termporale di 30~ps.
La tecnologia grazie ad una serie di test condotti con fasci di particelle in cui è stato anche dimostrato
che l'attuale calorimetro elettromagnetico di CMS, con un opportuno miglioramento dell'elettronica di lettura,
può raggiungere una risoluzione di 30~ps per energie maggiori di 20~GeV.
Lo studio per la definizione del rivelatore è accompagnato da studi di simulazione volti a evidenziare
il guadagno indotto dall'uso del tempo nella ricostruzione degli eventi. Questi studi hanno
dimostrato un generale miglioramento nell'efficienza di ricostruzione di osservabili di interesse
per la fisica che verrà esplorata nella fase ad alta luminosità.Although the Standard Model of particle physics (SM) describes with extreme success the fundamental interactions of matter it does not provide a solution for open questions of modern physics. The nature of cosmological dark matter, a quantum description of gravity and the hierarchy problem cannot included in the framework of the SM. For this reason several extensions have been proposed throughout the years to address these open problems. The beyond the standard model (BSM) frameworks often predict the existence of additional particles, either arising from additional symmetries introduced by the model or by the inclusion of gravity. Part of the parameter space of these models can be covered by experiments at LHC, since the predicted particles can have masses in the TeV range. The diphoton resonant production is sensitive to spin-0 and spin-2 BSM resonances. These can be originated by wrapped extra dimensions or extension of the Higgs sector which are typically included in BSM models. The excellent energy resolution achieved with the CMS electromagnetic calorimeter (ECAL) and the clean signature of the dipho- ton events makes this channel very attractive as a tool for the search of exotic resonances. The sensitivity of the search in the diphoton channel is subordinated to the ECAL energy resolution and the precision on the location of the interaction vertex. The search pre- sented in this work has been conducted on data collected by the CMS experiment at LHC with proton-proton collisions at a center-of-mass energy of 13 TeV, for a total integrated luminosity of 35.9fb −1 . No significant deviation from the Standard Model prediction has been highlighted by the analysis, thus exclusion limits on the graviton production cross- section have been established in the context of the Randall-Sundrum extra dimensions model. The limits varies between 6 fb and 0.1 fb depending on the mass and coupling of the resonance in the 0.5 < m < 4.5 TeV and 0.01 < κ < 0.2 ranges. The LHC program foresees an high luminosity phase starting from 2026 (HL-LHC), during which the instantaneous luminosity will reach the record value of 7.5×10 34 cm −2 s −1 , five times the current one. On one hand higher instantaneous luminosity will bring benefits to the physics analysis by providing a dataset 10 times larger than what will be available during the LHC phase but, on the other hand will pose severe challenges to the event reconstruction given the high number of overlapping collisions. CMS is already planning various actions and detector upgrades to match the physics goal of HL-LHC. Among those the introduction of time into the event reconstruction will require the installation of a completely new detector. Technologies suitable for the measurement of charged particles time with a precision of 30 ps have been identified through a series of tests with particles beam. In the same tests the intrinsic time resolution of the ECAL has been proved to be better than 20 ps for electrons and photons of at least 25 GeV. The R&D campaign has been coupled to simulation studies to quantify the expected gain in performance provided by a time-aware event reconstruction. The simulation studies show a general improvement for observable of interest for the HL-LHC physics program.
Books on the topic "Timing anomalies"
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Mathiesen, Amber, and Kali Roy. Common Indications. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780190681098.003.0005.
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This chapter describes common reasons for referral to a perinatal genetic counselor including age-related risks, personal and family history, ultrasound anomalies, teratogen exposure, recurrent pregnancy loss, and preconception counseling. Maternal and paternal age-related pregnancy risks are described, such as aneuploidy, single-gene conditions, and autism. A referral for a personal and/or family history of various conditions including single-gene conditions, aneuploidy, multifactorial conditions, birth defects, intellectual disability, developmental delay, autism, and consanguinity is described. The chapter reviews ultrasound anomalies and describes common ultrasound findings associated with aneuploidy, and hallmark ultrasound findings associated with particular genetic conditions, as well as identification of open neural tube defects. Teratogen exposure during pregnancy is discussed, including timing, dose, and duration and a description of typical features and symptoms associated with common teratogens. The chapter reviews the evaluation of pregnancy loss and stillbirth, male and female infertility, and referral for preconception counseling.
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Picone, Olivier, Christelle Vauloup-Fellous, and Laurent Mandelbrot. Varicella-Zoster Virus. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780190604813.003.0014.
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Chickenpox in a pregnant woman is uncommon, but it is a major concern for patients and their families, as well as for clinicians caring for pregnant women. Varicella infection during pregnancy is usually benign, but there can be serious consequences for both mother and child. Notably, fetal varicella syndrome (FVS) can happen when infection occurs before 21 weeks of gestation. It can present with serious neurological anomalies and unusual cicatricial skin lesions. Later in pregnancy, primary neonatal varicella may occur when the mother is infected in the peripartum period, and it can be life-threatening. The complications of varicella during pregnancy are reviewed, with an emphasis on early recognition, accurate timing of infection, and risk to the developing fetus and newborn infant. The impact of varicella vaccine on the epidemiology of these infections is reviewed, as well as indications for varicella-zoster virus (VZV)–specific immune globulin and antiviral therapy with acyclovir.
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Kitaoka, Akiyoshi. The Fraser-Wilcox Illusion and Its Extension. Oxford University Press, 2017. http://dx.doi.org/10.1093/acprof:oso/9780199794607.003.0068.
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The Fraser-Wilcox illusion is one of the anomalous motion illusions observed in a stationary image, and its extension, including “rotating snakes,” which has been used extensively via the Internet, are reviewed in this chapter. Perceptual dimorphism featuring the Fraser-Wilcox illusion is explained by an interaction between two different illusions. Darkening disambiguation of the Fraser-Wilcox illusion, perceptual dimorphism, the optimized Fraser-Wilcox illusions, the effect of age on the illusion magnitude, as well as the role of color including color enhancement are demonstrated and discussed. The timing-difference model and the eye-movement model are also explored. Recent studies that relate to these concepts are also examined.
Book chapters on the topic "Timing anomalies"
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Binder, Benjamin, Mihail Asavoae, Florian Brandner, Belgacem Ben Hedia, and Mathieu Jan. "Scalable Detection of Amplification Timing Anomalies for the Superscalar TriCore Architecture." In Formal Methods for Industrial Critical Systems, 151–69. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-58298-2_6.
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Kinner, E., M. Glatt, J. C. Aurich, and C. Garth. "Visual Analysis and Anomaly Detection of Material Flow in Manufacturing." In Proceedings of the 3rd Conference on Physical Modeling for Virtual Manufacturing Systems and Processes, 281–93. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-35779-4_15.
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AbstractThe automated tracking of objects in factories via real-time locating systems (RTLS) is gaining increased attention due to its improved availability, technical sophistication, and most of all, its plethora of applications. The tracking of workpieces through their production process, for example, unlocks a detailed understanding of timings, patterns, and bottlenecks. While research mostly focuses on technological advancements, the analysis of the generated data is often left unclear. We propose a visual analysis framework based on ultra-wide-band (UWB) RTLS tracking data of material flow for this purpose. With this, we present an analysis and define a practical approach for how factory-level data can be analyzed. Advanced algorithms adapted from non-adjacent research domains are used to process and detect anomalies in the data, which would otherwise be hidden behind oversimplified analysis methods. Our approach considers different levels of granularity for the analysis in its visualization and, therefore, scales with increasing data sizes effortlessly. We also generated a ground truth dataset of RTLS UWB data with labeled anomaly cases. Combined, we provide a full, end-to-end, efficient processing and multi-visualization analysis pipeline for self-contained yet generalizable UWB RTLS data.
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Wood, Dan. "Differences in sex development." In Oxford Textbook of Plastic and Reconstructive Surgery, edited by Oliver Fenton, 1313–20. Oxford University Press, 2021. http://dx.doi.org/10.1093/med/9780199682874.003.0114.
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Disorders of sexual development are a complex group of conditions with anomalies of the internal and external genitalia due to abnormal chromosomal and hormonal influences during development. Diagnosis and management, including timing of intervention, and both long-term cosmetic and functional outcomes are discussed in this chapter.
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Sudhakar V. Goparaju, Surya. "Perspective Chapter: Role of Genetics, Stem Cells in Reconstructive Surgery—Their Perspectives in Craniofacial Diseases and Syndromes." In Craniofacial Surgery - Recent Advances, New Perspectives and Applications [Working Title]. IntechOpen, 2023. http://dx.doi.org/10.5772/intechopen.109514.
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Genetic screening, counseling, and mapping play a vital role in identification of mutant genes/chromosomes, thereby preventing the progression of the disease in craniofacial anamolies, head and neck cancer in susceptible patients. Stem cells have a wide application in treating autoimmune diseases and systemic diseases, craniofacial anomalies, head and neck cancers, esthetic and reconstructive surgery, etc. At large, surgery has been the mainstay of treatment in both disease varieties. Targeted therapies with genetic engineering and stem cell transplantation go hand in hand for improving the prognosis of these diseases to a phenomenal extent. The identification of the disease at the level of chromosomal mutation stem cell therapy in conjunction with surgery is a suitable option to obtain satisfactory results in both the disease entities. This methodical combination aids in correction of the relapse and recurrence in craniofacial anomalies as well as head and neck cancers. This chapter projects and encourages insight into the perspective approach and the importance of combining whole genome sequencing and mapping along with stem cell therapy along with the conventional treatment modalities in treatment of craniofacial deformities, head and neck neoplasms with the right timing and proper case selection to appreciate better results.
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Lidral, Andrew C., and Katherine W. L. Vig. "Role of the Orthodontist in the Management of Patients with Cleft Lip and/or Palate." In Cleft Lip And Palate, 381–96. Oxford University PressNew York, NY, 2002. http://dx.doi.org/10.1093/oso/9780195139068.003.0029.
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Abstract The role of the orthodontist on a cleft palate team was defined when the cleft palate team approach was recognized as the most appropriate method to manage the care of patients with facial clefts. In the past, individuals with clefts and craniofacial anomalies underwent a succession of evaluations and hospitalizations by their independent caregivers. This individualized delivery of care was considered in the best interest of the patients in spite of additional hospital admissions and general anesthetics. However, this led to the fragmentation of care and higher costs and risks. A team approach for providing care has been developed and is the contemporary standard endorsed by the American Cleft Palate Association, which was established in 1943. In 1972, craniofacial teams became established as an extension to the cleft palate team, and the organization was renamed the American Cleft Palate-Craniofacial Association. This was a natural development to the cleft palate team as clinical geneticists and dysmorphologists became increasingly aware that facial clefts were part of a phenotypic spectrum of craniofacial anomalies (Shprintzen et al., 1985). The team approach to comprehensive care requires the orthodontist to work in a collaborative way to determine the timing and sequencing of treatment interventions. This patient-centered care by an interactive and evidence-based team of caregivers provides the basis for a rational approach to diagnosis and treatment planning and delivery. Because there are multiple methods and alternative treatment interventions available, the team approach to management requires that patients and their parents be aware of the choices with a risk/cost/benefit appraisal so that they can make an informed decision, understanding the consequences of the different options available, especially in light of emerging technologies and treatment modalities for which long-term outcomes are not available.
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Bhat, Mohd Shahid. "CT ANGIOGRAPHY." In MEDICAL DIAGNOSTICS: LABORATORY TO RADIOLOGICAL IMAGING. KAAV PUBLICATIONS, 2024. http://dx.doi.org/10.52458/9788196919528.2024.eb.ch-13.
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Globally, cardiovascular illnesses continue to be the primary cause of morbidity and mortality. With the development of sophisticated imaging technology, diagnostic methods have been completely transformed. One essential tool for evaluating cardiovascular architecture and pathology is CT angiography. This technique uses intravenous contrast material and X-ray technology to produce finely detailed, three-dimensional images (3D) of the body's blood vessels. Through the use of multi-detector CT scanners and sophisticated computer algorithms, CTA gives medical professionals high-resolution images that enable accurate assessment of venous and arterial diseases. By making blood vessels more visible, contrast enhancement makes it possible to spot anomalies like emboli, stenosis, and aneurysms. In cardiovascular diagnostics, CTA is essential because it provides a quick and precise way to assess the vascular system. For the best imaging results, the timing of the contrast agent's administration must coincide with the peak arterial enhancement. In addition to its diagnostic powers, CTA aids in treatment planning by offering a thorough comprehension of vascular anatomy and pathology. Though it works well, radiation exposure concerns highlight the need for careful application and, when appropriate, alternative modalities. The importance of CTA as a flexible and effective tool in contemporary medicine, aiding in the diagnosis and treatment of a broad range of vascular diseases.
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Gervais Ngueuteu Mbouna, Serge. "Fractional Calculus-Based Generalization of the FitzHugh-Nagumo Model: Biophysical Justification, Dynamical Analysis and Neurocomputational Implications." In Nonlinear Systems - Recent Developments and Advances [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.107270.
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In this chapter, the dynamical behavior of the incommensurate fractional-order FitzHugh-Nagumo model of neuron is explored in details from local stability analysis. First of all, considering that the FitzHugh-Nagumo model is a mathematical simplification of the Hodgkin-Huxley model, the considered model is derived from the fractional-order Hodgkin-Huxley model obtained taking advantage of the powerfulness of fractional derivatives in modeling certain biophysical phenomena as the dielectrics losses in cell membranes, and the anomalous diffusion of particles in ion channels. Then, it is shown that the fractional-order FitzHugh-Nagumo model can be simulated by a simple electrical circuit where the capacitor and the inductor are replaced by corresponding fractional-order electrical elements. Then, the local stability of the model is studied using the Theorem on the stability of incommensurate fractional-order systems combined with the Cauchy’s argument Principle. At last, the dynamical behavior of the model are investigated, which confirms the results of local stability analysis. It is found that the simple model can exhibit, among others, complex mixed mode oscillations, phasic spiking, first spike latency, and spike timing adaptation. As the dynamical richness of a neuron expands its computational capacity, it is thus obvious that the fractional-order FitzHugh-Nagumo model is more computationally efficient than its integer-order counterpart.
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Brazel, Anthony J., and Andrew W. Ellis. "The Climate of the Central Arizona and Phoenix Long-Term Ecological Research Site (CAP LTER) and Links to ENSO." In Climate Variability and Ecosystem Response in Long-Term Ecological Research Sites. Oxford University Press, 2003. http://dx.doi.org/10.1093/oso/9780195150599.003.0016.
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The Central Arizona and Phoenix LTER (CAP LTER) is one of two urban LTERs in the world network (Grimm et al. 2000; see http://caplter.asu.edu). Many LTER sites display a detectable climatic signal related to the El Niño–Southern Oscillation (ENSO) phenomenon (Greenland 1999). The purpose of this chapter is twofold: (1) to provide some insight into the role of the tropical Pacific Ocean as a driver of several climatic (and thus, ecologically related) variables in the CAP LTER location of central Arizona, and (2) to suggest the linkages of ENSO events to selected ecosystem processes near and within the geographical region of CAP LTER (figure 7.1a). From past studies, it is clear that the seasonal and annual climate regimes of the southwestern United States, particularly water-related parameters, are linked to the periodicities and anomalies of what is known as the Multivariate ENSO Index (MEI) and Southern Oscillation Index (SOI) (e.g., Wolter 1987; Molles and Dahm 1990; Redmond and Koch 1991; Woolhiser and Keefer 1993; Wolter and Timlin 1993; Cayan and Redmond 1994; Redmond and Cayan 1994; Cayan et al. 1999; Redmond and Cayan 1999; Simpson and Colodner 1999; Redmond 2000; and Mason and Goddard 2001). In Arizona, and especially in the CAP LTER region, precipitation is bimodal during the year with peaks in winter (mostly midlatitudederived frontal storms) and in mid-to-late summer, mostly in the form of convective thunderstorms during the North American monsoon season. Recent studies show a strong connection between ENSO and winter moisture in Arizona, such that it is even possible to forecast impending conditions in advance (Pagano et al. 1999). These studies have established relationships between the climate of the southwest ern United States and ENSO by demonstrating monthly and daily timescale effects on inputs of moisture and resultant streamflow in Arizona (e.g., Molles and Dahm 1990; Cayan et al. 1999; and Simpson and Colodner 1999). The synoptic- and largescale circulation patterns associated with anomalies of MEI/SOI in the southwestern United States provide additional insight into regional forces that drive the CAPLTER climate (e.g., Redmond and Koch 1991). Generally, when the warm phase of the tropical Pacific Ocean occurs (El Niño, thus negative SOI, positive MEI), across the Southwest precipitation is generally anomalously high.
Conference papers on the topic "Timing anomalies"
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Kadlec, Albrecht, Raimund Kirner, and Peter Puschner. "Avoiding Timing Anomalies Using Code Transformations." In 2010 13th IEEE International Symposium on Object/Component/Service-Oriented Real-Time Distributed Computing. IEEE, 2010. http://dx.doi.org/10.1109/isorc.2010.27.
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Iglesias, Félix, and Tanja Zseby. "Are Network Covert Timing Channels Statistical Anomalies?" In ARES '17: International Conference on Availability, Reliability and Security. New York, NY, USA: ACM, 2017. http://dx.doi.org/10.1145/3098954.3106067.
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Lin, Ching-Chi, Mario Günzel, Junjie Shi, Tristan Taylan Seidl, Kuan-Hsun Chen, and Jian-Jia Chen. "Scheduling Periodic Segmented Self-Suspending Tasks without Timing Anomalies." In 2023 IEEE 29th Real-Time and Embedded Technology and Applications Symposium (RTAS). IEEE, 2023. http://dx.doi.org/10.1109/rtas58335.2023.00020.
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Adatte, Thierry, Eric Font, André Mbabi Bitchong, Gerta Keller, Blair Schoene, Kyle M. Samperton, and Syed F. R. Khadri. "TIMING AND TEMPO OF DECCAN VOLCANISM REVEALED BY MERCURY ANOMALIES." In GSA Annual Meeting in Denver, Colorado, USA - 2016. Geological Society of America, 2016. http://dx.doi.org/10.1130/abs/2016am-285123.
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Binder, Benjamin, Mihail Asavoae, Florian Brandner, Belgacem Ben Hedia, and Mathieu Jan. "The Role of Causality in a Formal Definition of Timing Anomalies." In 2022 IEEE 28th International Conference on Embedded and Real-Time Computing Systems and Applications (RTCSA). IEEE, 2022. http://dx.doi.org/10.1109/rtcsa55878.2022.00016.
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Kirner, Raimund, Albrecht Kadlec, and Peter Puschner. "Precise Worst-Case Execution Time Analysis for Processors with Timing Anomalies." In 2009 21st Euromicro Conference on Real-Time Systems (ECRTS). IEEE, 2009. http://dx.doi.org/10.1109/ecrts.2009.8.
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Sithirasenan, Elankayer, and Vallipuram Muthukkumarasamy. "Detecting Security Threats in Wireless LANs Using Timing and Behavioral Anomalies." In 2007 15th IEEE International Conference on Networks. IEEE, 2007. http://dx.doi.org/10.1109/icon.2007.4444063.
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Benedicte, Pedro, Jaume Abella, Carles Hernandez, Enrico Mezzetti, and Francisco J. Cazorla. "Towards limiting the impact of timing anomalies in complex real-time processors." In ASPDAC '19: 24th Asia and South Pacific Design Automation Conference. New York, NY, USA: ACM, 2019. http://dx.doi.org/10.1145/3287624.3287655.
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Binder, Benjamin, Mihail Asavoae, Belgacem Ben Hedia, Florian Brandner, and Mathieu Jan. "Is This Still Normal? Putting Definitions of Timing Anomalies to the Test." In 2021 IEEE 27th International Conference on Embedded and Real-Time Computing Systems and Applications (RTCSA). IEEE, 2021. http://dx.doi.org/10.1109/rtcsa52859.2021.00024.
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Mohan, Sibin, and Frank Mueller. "Merging State and Preserving Timing Anomalies in Pipelines of High-End Processors." In 2008 IEEE 29th Real-Time Systems Symposium (RTSS). IEEE, 2008. http://dx.doi.org/10.1109/rtss.2008.12.
Full textReports on the topic "Timing anomalies"
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Simandl, G. J., R. J. D'Souza, S. Paradis, and J. Spence. Rare-earth element content of carbonate minerals in sediment-hosted Pb-Zn deposits, southern Canadian Rocky Mountains. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/328001.
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Paleozoic platform carbonate rocks of the Rocky Mountains host Mississippi Valley-type (MVT), magnesite, barite, and REE-barite-fluorite deposits. Farther west, platform carbonate rocks of the Kootenay Arc host MVT and fracture-controlled replacement (FCR) deposits. This is the first systematic LA-ICP-MS study of carbonates in MVT and FCR deposits. We investigated seven MVT deposits in the Rocky Mountains, and five MVT deposits in the Kootenay Arc. None of the post-Archean Australian shale (PAAS)-normalized REE profiles show light REE (LREE) depletion and strong negative Ce anomalies characteristic of modern seawater: some profiles are nearly flat; others show depletion in LREE similar to seawater but without negative Ce anomalies; others are middle REE enriched. Carbonates with a strong positive Eu anomaly precipitated from or interacted with different fluids than carbonates with flatter profiles without a strong positive Eu anomaly. REE signatures reflect crystallization conditions of primary carbonates, and crystallization and re-equilibration conditions of carbonates with ambient fluids during diagenesis, deep burial, and/or metamorphic recrystallization. Chemical evolution of fluids along their migration path, fluid-to-rock ratio, fluid acidity, redox, and temperature also influence REE profile shape, which helps establish genetic and timing constraints on studied deposits and improves knowledge of the metallogeny of the Kootenay Arc and Rocky Mountains.
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Taucher, Jan, and Markus Schartau. Report on parameterizing seasonal response patterns in primary- and net community production to ocean alkalinization. OceanNETs, November 2021. http://dx.doi.org/10.3289/oceannets_d5.2.
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We applied a 1-D plankton ecosystem-biogeochemical model to assess the impacts of ocean alkalinity enhancement (OAE) on seasonal changes in biogeochemistry and plankton dynamics. Depending on deployment scenarios, OAE should theoretically have variable effects on pH and seawater pCO2, which might in turn affect (a) plankton growth conditions and (b) the efficiency of carbon dioxide removal (CDR) via OAE. Thus, a major focus of our work is how different magnitudes and temporal frequencies of OAE might affect seasonal response patterns of net primary productivity (NPP), ecosystem functioning and biogeochemical cycling. With our study we aimed at identifying a parameterization of how magnitude and frequency of OAE affect net growth rates, so that these effects could be employed for Earth System Modell applications. So far we learned that a meaningful response parameterization has to resolve positive and negative anomalies that covary with temporal shifts. As to the intricacy of the response patterns, the derivation of such parameterization is work in progress. However, our study readily provides valuable insights to how OAE can alter plankton dynamics and biogeochemistry. Our modelling study first focuses at a local site where time series data are available (European Station for Time series in the Ocean Canary Islands ESTOC), including measurements of pH, concentrations of total alkalinity, dissolved inorganic carbon (DIC), chlorophyll-a and dissolved inorganic nitrogen (DIN). These observational data were made available by Andres Cianca (personal communication, PLOCAN, Spain), Melchor Gonzalez and Magdalena Santana Casiano (personal communication, Universidad de Las Palmas de Gran Canaria). The choice of this location was underpinned by the fact that the first OAE mesocosm experiment was conducted on the Canary Island Gran Canaria, which will facilitate synthesizing our modelling approach with experimental findings. For our simulations at the ESTOC site in the Subtropical North Atlantic we found distinct, non-linear responses of NPP to different temporal modes of alkalinity deployment. In particular, phytoplankton bloom patterns displayed pronounced temporal phase shifts and changes in their amplitude. Notably, our simulations suggest that OAE can have a slightly stimulating effect on NPP, which is however variable, depending on the magnitude of OAE and the temporal mode of alkalinity addition. Furthermore, we find that increasing alkalinity perturbations can lead to a shift in phytoplankton community composition (towards coccolithophores), which even persists after OAE has stopped. In terms of CDR, we found that a decrease in efficiency with increasing magnitude of alkalinity addition, as well as substantial differences related to the timing of addition. Altogether, our results suggest that annual OAE during the right season (i.e. physical and biological conditions), could be a reasonable compromise in terms of logistical feasibility, efficiency of CDR and side-effects on marine biota. With respect to transferability to global models, the complex, non-linear responses of biological processes to OAE identified in our simulations do not allow for simple parameterizations that can easily adapted. Dedicated future work is required to transfer the observed responses at small spatiotemporal scales to the coarser resolution of global models.
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de Caritat, Patrice, Brent McInnes, and Stephen Rowins. Towards a heavy mineral map of the Australian continent: a feasibility study. Geoscience Australia, 2020. http://dx.doi.org/10.11636/record.2020.031.
Full textAbstract:
Heavy minerals (HMs) are minerals with a specific gravity greater than 2.9 g/cm3. They are commonly highly resistant to physical and chemical weathering, and therefore persist in sediments as lasting indicators of the (former) presence of the rocks they formed in. The presence/absence of certain HMs, their associations with other HMs, their concentration levels, and the geochemical patterns they form in maps or 3D models can be indicative of geological processes that contributed to their formation. Furthermore trace element and isotopic analyses of HMs have been used to vector to mineralisation or constrain timing of geological processes. The positive role of HMs in mineral exploration is well established in other countries, but comparatively little understood in Australia. Here we present the results of a pilot project that was designed to establish, test and assess a workflow to produce a HM map (or atlas of maps) and dataset for Australia. This would represent a critical step in the ability to detect anomalous HM patterns as it would establish the background HM characteristics (i.e., unrelated to mineralisation). Further the extremely rich dataset produced would be a valuable input into any future machine learning/big data-based prospectivity analysis. The pilot project consisted in selecting ten sites from the National Geochemical Survey of Australia (NGSA) and separating and analysing the HM contents from the 75-430 µm grain-size fraction of the top (0-10 cm depth) sediment samples. A workflow was established and tested based on the density separation of the HM-rich phase by combining a shake table and the use of dense liquids. The automated mineralogy quantification was performed on a TESCAN® Integrated Mineral Analyser (TIMA) that identified and mapped thousands of grains in a matter of minutes for each sample. The results indicated that: (1) the NGSA samples are appropriate for HM analysis; (2) over 40 HMs were effectively identified and quantified using TIMA automated quantitative mineralogy; (3) the resultant HMs’ mineralogy is consistent with the samples’ bulk geochemistry and regional geological setting; and (4) the HM makeup of the NGSA samples varied across the country, as shown by the mineral mounts and preliminary maps. Based on these observations, HM mapping of the continent using NGSA samples will likely result in coherent and interpretable geological patterns relating to bedrock lithology, metamorphic grade, degree of alteration and mineralisation. It could assist in geological investigations especially where outcrop is minimal, challenging to correctly attribute due to extensive weathering, or simply difficult to access. It is believed that a continental-scale HM atlas for Australia could assist in derisking mineral exploration and lead to investment, e.g., via tenement uptake, exploration, discovery and ultimately exploitation. As some HMs are hosts for technology critical elements such as rare earth elements, their systematic and internally consistent quantification and mapping could lead to resource discovery essential for a more sustainable, lower-carbon economy.
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Gravity - Bouguer anomalies, Timmins, Ontario, Quebec and Northwest Territories. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1990. http://dx.doi.org/10.4095/131327.
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