True Date Research Articles

An assessment of the minimum timing of ice free conditions of the western Laurentide Ice Sheet

This study presents an investigation of the minimum timing of retreat of the western Laurentide Ice Sheet, which covered parts of Canada and the northern United States during the Wisconsin glaciation. The retreat of the ice sheet is poorly constrained due to low spatial resolution of chronological data that indicate ice free conditions. A limitation of radiocarbon and luminescence dating methods is that it is only possible to determine the time when it is certain that ice is absent from a region, which may differ substantially from the true date of ice margin retreat. The minimum timing of ice free conditions is determined using a model of ice sheet retreat, inferred from landforms that formed during the late stages of glaciation, and extrapolating the calibrated probability distribution of chronological data in the opposite direction. The analysis excludes radiocarbon samples from materials that have been shown to give artificially old ages, such as bulk sediments. The results of the analysis identify 55 dates that have the most impact on the model. The retreat of the western Laurentide Ice Sheet commenced by at least 15 000 cal yr BP, while the minimum timing of ice free conditions between the Laurentide Ice Sheet and the Cordillera is after 11 000 cal yr BP. A lack of data in the Keewatin sector prevents the determination of a precise timing of ice free conditions in the last vestiges of the Laurentide Ice Sheet. The model provides a guide to where additional samples could improve chronological control on ice margin location.

Day-specific probabilities of conception in fertile cycles resulting in spontaneous pregnancies

When, within the female cycle, does conception occur in spontaneously fertile cycles? This study provides reference values of day-specific probabilities of date of conception in ongoing pregnancies. The maximum probability of being within a 5-day fertile window was reached on Day 12 following the last menstrual period (LMP). The true date of conception is not observable and may only be estimated. Accuracy of these estimates impacts on obstetric management of ongoing pregnancies. Timing of ovulation and fertility has been extensively studied in prospective studies of non-pregnant fertile women using error-prone proxies, such as hormonal changes, body-basal temperature and ultrasound, yielding day-specific probabilities of conception and fertile windows. In pregnant women, date of conception may be retrospectively estimated from early pregnancy fetal measurement by ultrasound. Retrospective analysis of consecutive pregnancies in women referred for routine first-trimester screening, over a 3-year period (2009-2011) in a single ultrasound center (n = 6323). Within the overall population, 5830 cases with a certain date of last menses were selected for analysis. The date of conception was estimated using a crown-rump length biometry and an equation derived from IVF/ICSI pregnancies. Day-specific probabilities of conception were estimated across several covariates, including age, cycle characteristics and ethnicity, using deconvolution methods to account for measurement error. Overall, the day-specific probability of conception sharply rises at 7 days after the LMP, reaching its maximum at 15 days and returning to zero by 25 days. Older women tend to conceive earlier within their cycle, as did women with regular cycles and white and black women compared with Asian ethnicity. The probability of being within the fertile window was 2% probability at Day 4, a maximum probability of 58% at Day 12 and a 5% probability by Day 21 of the cycle. Although conception is believed to occur within hours following ovulation, a discrepancy is theoretically possible. However, when comparing our results to those of prospective studies, no such difference was found. The equation used for estimating the date of pregnancy was estimated in IVF/ICSI pregnancies, which could lead to potential bias in spontaneous pregnancies. However, in our population, the observed bias was negligible. Non-fertile cycles and early pregnancy losses are necessarily overlooked because of the nature of our data. Because of the wider access to retrospective data and the potential bias in prospective studies of ovulation monitoring, this study should broaden the perspectives of future epidemiologic research in fertility and pregnancy monitoring. None.

Distribution of Fin-fish Eggs and Larvae from Point Calimere and Muthupettai, South East Coast of India

Eggs and larvae of the fishes are known as Ichthyoplankton. Mostly, the eggs are a planktonic and they cannot swim effectively and drift with the ocean currents. A fish larva is a part of zooplankton there consumes small organisms. It is a bio-indicator of an aquatic ecosystem. In the present study, totally 748/100 m3 fish eggs were collected from both the stations of Point Calimere and Muthupettai. The finfish eggs were recorded maximum in 18/100 m3 and 24/100 m3 at station I and II and the larvae were recorded maximum in 8/100 m3 and 12/100 m3 at station I and II respectively. When compare two sampling station the maximum of fish eggs and larvae were observed station I than there other station. Sensitive development stages of the fish, like egg and larvae which can affect mainly on predatory problem, environmental parameters and manmade activities. The true diversity date is need for the species conservation and maintenance.

Regime-switching in volatility and correlation structure using range-based models with Markov-switching

This study examines latent shifts in the conditional volatility and correlation for the U.S. stock and T-bond data using the two-state Markov-switching range-based volatility and correlation models. This paper comes up with clear evidence of volatility regime-switching in stock indices and T-bond over the crisis period. As regards the process of correlation, we also find evidence of regime changes in correlations between stock indices and T-bond over several financial crises. We conclude that the phenomena of both volatility and correlation regime-switching are triggered by these financial crises. In addition, the range-based volatility and correlation model with regime-switching method could explicitly point out the true date of structure changes in the data generating process for volatility and correlation variables.

Informed deferral: A moral requirement for entry into the hepatitis C virus treatment warehouse

Informed deferral: A moral requirement for entry into the hepatitis C virus treatment warehouse

The Diversity of Class II Transposable Elements in Mammalian Genomes Has Arisen from Ancestral Phylogenetic Splits during Ancient Waves of Proliferation through the Genome

DNA transposons make up 3% of the human genome, approximately the same percentage as genes. However, because of their inactivity, they are often ignored in favor of the more abundant, active, retroelements. Despite this relative ignominy, there are a number of interesting questions to be asked of these transposon families. One particular question relates to the timing of proliferation and inactivation of elements in a family. Does an ongoing process of turnover occur, or is the process more akin to a life cycle for the family, with elements proliferating rapidly before deactivation at a later date? We answer this question by tracing back to the most recent common ancestor (MRCA) of each modern transposon family, using two different methods. The first method identifies the MRCA of the species in which a family of transposon fossils can still be found, which we assume will have existed soon after the true origin date of the transposon family. The second method uses molecular dating techniques to predict the age of the MRCA element from which all elements found in a modern genome are descended. Independent data from five pairs of species are used in the molecular dating analysis: human–chimpanzee, human–orangutan, dog–panda, dog–cat, and cow–pig. Orthologous pairs of elements from host species pairs are included, and the divergence dates of these species are used to constrain the analysis. We discover that, in general, the times to element common ancestry for a given family are the same for the different species pairs, suggesting that there has been no order-specific process of turnover. Furthermore, for most families, the ages of the common ancestor of the host species and of that of the elements are similar, suggesting a life cycle model for the proliferation of transposons. Where these two ages differ, in families found only in Primates and Rodentia, for example, we find that the host species date is later than that of the common ancestor of the elements, implying that there may be large deletions of elements from host species, examples of which were found in their ancestors.

Ratio-based estimators for a change point in persistence

We study estimation of the date of change in persistence, from I(0) to I(1) or vice versa. Contrary to statements in the original papers, our analytical results establish that the ratio-based break point estimators of Kim [Kim, J.Y., 2000. Detection of change in persistence of a linear time series. Journal of Econometrics 95, 97–116], Kim et al. [Kim, J.Y., Belaire-Franch, J., Badillo Amador, R., 2002. Corringendum to “Detection of change in persistence of a linear time series”. Journal of Econometrics 109, 389–392] and Busetti and Taylor [Busetti, F., Taylor, A.M.R., 2004. Tests of stationarity against a change in persistence. Journal of Econometrics 123, 33–66] are inconsistent when a mean (or other deterministic component) is estimated for the process. In such cases, the estimators converge to random variables with upper bound given by the true break date when persistence changes from I(0) to I(1). A Monte Carlo study confirms the large sample downward bias and also finds substantial biases in moderate sized samples, partly due to properties at the end points of the search interval.

Parasites reveal movement of bats between the New and Old Worlds

The global distribution of bat taxa indicates that the Atlantic and Pacific Oceans are effective barriers to movement between the Old and New Worlds. For instance, one of the major suborders, Yinpterochiroptera, has an exclusively Old World distribution, and within the other, Yangochiroptera, no species and only five genera are common to both. However, as bats are sometimes blown out to sea, and have colonised isolated islands, occasional natural movement between the New and Old Worlds does appear to be possible. Here we identify new genotypes of a blood parasite, Trypanosoma dionisii, in Old World bats that are closely related to South American strains. Using highly conservative calibration points, divergence of Old and New World strains is estimated to have occurred 3.2–5.0million years ago (MYA), depending on the method used (upper 95% CL for maximum time 11.4MYA). The true date of divergence is likely to be considerably more recent. These results demonstrate that taxon-specific parasites can indicate historical movements of their hosts, even where their hosts may have left no lasting phylogenetic footprint.

‘Intolerable Flippancy’: The Arnot Robertson V. Mgm Libel Case (1946–1950) and The Evolution of BBC Policy on Broadcast Film Criticism

This article examines the ultimately unsuccessful libel case brought by the novelist and BBC film critic E. Arnot Robertson against Metro-Goldwyn-Mayer. The action followed a letter the film company sent to Robertson’s employer in 1946, asserting she was ‘out of touch’ with public taste, excluding her from their press screenings and requested the broadcaster’s assistance in preventing her from reviewing further MGM films on air. Robertson charged the film company with libelling her professional competence and imperilling her earnings. This article explores the origins and outcomes of the ensuing three-year legal dispute. Drawing on trade journals, law reports, press coverage and BBC records, the article considers the contrasting models of the ‘audience’ underpinning the wider conflict between the film trade and the ‘quality’ critics. It explores the role of BBC policy and ‘broadcast style’ in making radio criticism a flashpoint and traces the specific circumstances that led the two parties into court. Finally, it considers the lasting legal and cultural consequences of the case. Turner (Robertson) v. MGM redefined the legal meaning of ‘fair comment’, it reshaped BBC policy on broadcast criticism, and shifted the consensus on what constituted responsible and professional criticism – making wit a less respectable critical tool.

Pauline Cerasoli Lecture

Excellence in Academic Physical Therapy: What Is It and How Do We Get There? INTRODUCTION The purpose of this lecture is to honor Pauline Cerasoli. The best way to honor her - as well as those past generations of leaders and visionaries who have brought us to this point in our profession s development - is to accept the challenge that they have handed down to us. They have passed us the baton. If we look very carefully (and use our imaginations), we can see some words printed on that baton: "Pursue excellence!" Since this word - excellence - is the subject of my lecture, perhaps we should begin by considering its definition. My dictionary defines excellence as "the state, quality or condition of excelling; surpassing others; superiority; pre-eminence."1 This makes us a bit uncomfortable, doesn't it? Excellence seems to be defined by the notion that we achieve excellence in some sort of competition with others. But the pursuit of excellence should not make us uncomfortable, if we understand that excellence is not merely a state; it is rather a process, or more properly - a continual striving to be better, to be the best that we can be. In striving to achieve excellence, it is not the surpassing of others that is important, it is the surpassing of ourselves, or, more properly, of what we have previously accomplished. Excellence should he considered as an important value, and a goal to be pursued* This is what our past generations of leaders, including Pauline Cerasoli, teach us. This is the legacy that they pass on to us. We should note that 90 years ago last month, the physical therapy profession was born in the United States. On January 15, 1921, 30 former reconstruction aides met at Keen's Chop House in New York City to form the organization that we now know as the American Physical Therapy Association (APTA).2 This was the true birth date of the profession. What went before (for example, reconstruction aides) was a gestational period. On this date, the profession developed an organization and an identity. Over the ensuing 90 years, physical therapists with vision and hard work and courage built the profession that we know today. Our past generations of leaders have brought us, at least in a metaphorical sense, to the proverbial mountaintop, where we can see the "promised land." There is no better description of that promised land than Vision 2020 (Figure 1). It envisions that by the year 2020, physical therapy will be provided by ". . . doctors of physical therapy, recognized by consumers and other health care professionals as the practitioners of choice to whom consumers have direct access . . . ."3 In other words, the promised land is full direct access for consumers and full partnership in the US health care system for physical therapists. Since Vision 2020 was first written and adopted by the APTA in 2000, there has been a tendency to look at it as if it were guaranteed, but it is far from that. What will get us there, and beyond? We face critical challenges to achieve that promise and an uncertain future, given the political, economic, and social turmoil of our times. Indeed, there is significant potential for radical changes in the health care system that do not necessarily include us. Given the risks and challenges, what is it that will allow us to achieve this goal: recognition as practitioners of choice and full partnership as autonomous professionals? The principal argument that I am making in this lecture is this: The essential characteristic of a profession that would achieve such recognition is a strong academic foundation. AN EXAMPLE: ACADEMIC MEDICINE To begin making this argument, I would like us to consider the development of the medical profession in the united states. Specifically, I ask the following question: Why has the medical profession achieved clear supremacy or dominance in our health care system? I would argue that academic medicine is the foundation of that success. …

Comparative case studies of the effects of inflation targeting in emerging economies

This paper examines the question of whether inflation targeting is an effective policy tool in emerging economies using a novel non-experimental evaluation approach. In particular, we adopt synthetic control methods to assess the effect that inflation targeting has had on each emerging economy that adopted such policies in the 1990s and 2000s. The evidence suggests that inflation targeting helped Colombia, the Czech Republic, Hungary and Poland reduce their inflation rates. Although Chile is often regarded as a poster child for inflation targeting policies in emerging economies, no significant reductions in inflation levels were found when a later policy start date some analysts believe to be more reflective of the true policy adoption date was used.

Applying Sensitivity Analyses to Overall Survival in Cancer Clinical Trials

TO THE EDITOR: “Role of Sensitivity Analyses in Assessing Progression-Free Survival in Late-Stage Oncology Trials” by Bhattacharya et al is an important statistical technique that assesses whether the results of phase III trials are robust and likely to be generalizable. The authors focus their comments and state that it is “important to conduct additional analyses (sensitivity analyses) of studies where progression-free survival (PFS) or time to tumor progression (TTP) is the primary end point.” Thus, implied in their emphasis is that overall survival (OS), the ultimate gold-standard outcome (the time from random assignment to death), may not be subject to confounding issues and does not require similar consideration. Bhattacharya et al state that “the documented date of first progression is often after the actual true (unknown) date of progression, which is not the case for OS.” However, they do not consider events that could similarly affect the timing of the OS primary event. Death, although an objective and measurable event, is affected by various clinical acts that can substantially influence this outcome. It is not the issue of when death occurred but various influences that affect the outcome. For instance, similar patients failing interventional therapy at the same time point after therapy may be kept alive (eg, avoiding the primary outcome) by heroic measures such as intensive care unit care or simple measures such as treating a pneumonia, or some may have only basic noninterventional hospice/end-of-life therapy offered that does not artificially prolong survival. Additionally, patients with bulky tumors compared with those with trivial tumor burdens, similarly failing therapy at the same time point without further therapy, may have different survival outcomes unrelated to the primary interventional therapy. It is therefore equally important for sensitivity testing to be pursued when phase III studies are positive for OS when differences are statistically different, but not robust biologically, because it is becoming more common for outcomes to be measured in a few weeks or months when large numbers of patients are entered on a trial. This is especially important when drugs or biologic are approved for generalizable intervention based on modest time increments for OS.

Searching for non‐indigenous species: rapidly delimiting the invasion boundary

AbstractAim At first detection, little information is typically known about an invader’s characteristics, true arrival date or spatial extent. Yet, before management options such as control or eradication can be considered, we need to know where a nuisance species has already spread. This is particularly difficult because of stochastic processes. Here, we develop an approach that requires little a priori information, yet accurately delimits the range of a biological invader.Location We used a simulated landscape, subjected to stochasticity inherent in establishment and spread, to test novel theory for delimiting locally spreading populations.Methods We distinguish three stages to identify the boundary of an invasion, which we term Approach, Decline, Delimit (ADD). Our ADD algorithm uses general characteristics of the invasion pattern, obtained during a search for occupied sites, in combination with sampling and probability theory to delimit the invasion. We compare ADD against four naïve delimitation strategies, for long and normal dispersal kernels.Results Our results illustrate the potential difficulty in delimiting invasions. Naïve strategies, such as stopping when the invader is absent, typically failed to properly delimit the invasion. In contrast, ADD operated relatively efficiently, and was robust to habitat heterogeneity and knowledge of the true epicentre, but was sensitive to the sparseness of the invasion. For long‐distance dispersal kernels, ADD had 80% accurate delimitations when c. 5% or more of the cells were occupied within the invasion boundary; for normal dispersal kernels, ADD had 95% accurate delimitations when c. 2.5% or more of the cells were occupied.Main conclusions There is virtually no existing theory for delimiting invasions. ADD is efficient and accurate, even with unknown time of invasion, unknown dispersal kernels, stochastic establishment dynamics and spatial heterogeneity, except for very low invasion densities.

Structural Examination of Easel Paintings with Optical Coherence Tomography

Identification of the order, thickness, composition, and possibly the origin of the paint layers forming the structure of a painting, that is, its stratigraphy, is important in confirming its attribution and history as well as planning conservation treatments. The most common method of examination is analysis of a sample collected from the art object, both visually with a microscope and instrumentally through a variety of sophisticated, modern analytical tools. Because of its invasiveness, however, sampling is less than ideally compatible with conservation ethics; it is severely restricted with respect to the amount of material extirpated from the artwork. Sampling is also rather limited in that it provides only very local information. There is, therefore, a great need for a noninvasive method with sufficient in-depth resolution for resolving the stratigraphy of works of art. Optical coherence tomography (OCT) is a noninvasive, noncontact method of optical sectioning of partially transparent objects, with micrometer-level axial resolution. The method utilizes near-infrared light of low intensity (a few milliwatts) to obtain cross-sectional images of various objects; it has been mostly used in medical diagnostics. Through the serial collection of many such images, volume information may be extracted. The application of OCT to the examination of art objects has been in development since 2003. In this Account, we present a short introduction to the technique, briefly discuss the apparatus we use, and provide a paradigm for reading OCT tomograms. Unlike the majority of papers published previously, this Account focuses on one, very specific, use of OCT. We then consider two examples of successful, practical application of the technique. At the request of a conservation studio, the characteristics of inscriptions on two oil paintings, originating from the 18th and 19th centuries, were analyzed. In the first case, it was possible to resolve some questions concerning the history of the work. From an analysis of the positions of the paint layers involved in three inscriptions in relation to other strata of the painting, the order of events in its history was resolved. It was evident that the original text had been overpainted and that the other inscriptions were added later, thus providing convincing evidence as to the painting's true date of creation. In the second example, a painting was analyzed with the aim of confirming the possibility of forgery of the artist's signature, and evidence strongly supporting this supposition is presented. These two specific examples of successful use of the technique on paintings further demonstrate how OCT may be readily adaptable to other similar tasks, such as in the fields of forensic or materials science. In a synergistic approach, in which information is obtained with a variety of noninvasive techniques, OCT is demonstrably effective and offers great potential for further development.

A Simulation Study of Predicting Flush Date

For Canada's boreal forest region, the accurate modelling of the timing of the appearance of aspen leaves is important to forest fire management, as it signifies the end of the spring fire season that occurs after snowmelt. This article compares two methods, a midpoint rule and a conditional expectation method used to estimate the true flush date for interval-censored data from a large set of fire-weather stations in Alberta, Canada. The conditional expectation method uses the interval censored kernel density estimator of Braun et al. (2005). The methods are compared via simulation, where true flush dates were generated from a normal distribution and then converted into intervals by adding and subtracting exponential random variables. The simulation parameters were estimated from the data set and several scenarios were considered. The study reveals that the conditional expectation method is never worse than the midpoint method, and that there is a significant advantage to this method when the intervals are large. An illustration of the methodology applied to the Alberta data set is also provided.

John Collings-Wells

John was born on the night of 5/6 June 1922 on the family coffee farm in Kenya. There were no clocks, so he never knew his true date of birth....

New innovational outlier unit root test with a break at an unknown time

The Perron test which is based on a Dickey–Fuller test regression is a commonly employed approach to test for a unit root in the presence of a structural break of unknown timing. In the case of an innovational outlier (IO), the Perron test tends to exhibit spurious rejections in finite samples when the break occurs under the null hypothesis. In the present paper, a new Perron-type IO unit root test is developed. It is shown in Monte Carlo experiments that the new test does not over-reject the null hypothesis. Even for the case of a level and slope break for trending data, the empirical size is near its nominal level. The test distribution equals the case of a known break date. Furthermore, the test is able to identify the true break date very accurately even for small breaks. As an application serves the Nelson–Plosser data set.

When did Louis Pasteur present his memoir on the discovery of molecular chirality to the Académie des sciences? Analysis of a discrepancy

Louis Pasteur presented his historic memoir on the discovery of molecular chirality to the Académie des sciences in Paris on May 22nd, 1848. The literature, however, nearly completely ignores this date, widely claiming instead May 15th, 1848, which first surfaced in 1922 in Pasteur's collected works edited by his grandson Louis Pasteur Vallery-Radot. On May 21st, 1848, i.e., one day before Pasteur's presentation in Paris, his mother died in Arbois, eastern France. Informed at an unknown point in time that she was "very ill," Pasteur left for Arbois only after his presentation. Biographies of Pasteur by his son-in-law René Vallery-Radot or the grandson, and Pasteur's collected correspondence edited by the grandson are incomprehensibly laconic or silent about the historic presentation. While no definite conclusions are possible, the evidence strongly suggests a deliberate alteration of the record by the biographer relatives, presumably for fear of adverse public judgment of Pasteur for a real or perceived insensitivity to a grave family medical emergency. Such fear would have been in accord with their hagiographic portrayal of Pasteur, and the findings raise questions concerning the extent of their zeal in protecting his "demigod" image. Universal recognition of the true date of Pasteur's announcement of molecular chirality is long overdue.

Catalogue Technique in Dionysius Periegetes

Dionysios gehört zu den interessantesten Problemen der griechischen Literaturgeschichte.Knaack (1905) 916.34f.Within the general context of increasing interest in Greek literature in the Roman period, interest in Dionysius the Periegete is certainly on the rise. Our knowledge of his extensive textual tradition is still expanding, and further editions are under way; the ideologies that structure his work have been explored in a series of publications by Christian Jacob (1990, 1991); and the welcome increase in the volume of publications over the last five years or so includes a collection of essays which is especially geared to one of my themes in this essay, Dionysius' relations with Hellenistic poetry and poets. Yet there are some basic aspects of his poetics that remain un-, or under-, studied. At the heart of the matter, I suggest, are two major backgrounds that need to be explored further.The first is the reception of Hellenistic poetry in the imperial period. Dionysius is a neo-Hellenistic poet. Indeed, he is so convincing a neo-Hellenistic poet that a critic as astute as Tycho Mommsen placed him in the first century BCE on the basis of a whole array of stylistic and metrical and other sorts of linguistic criteria. Dionysius' true date has been known for a century and a quarter; but we are really none the wiser about what it was that gave rise to this extraordinarily competent and convincing Hellenistic imitation. It is not only that he imitates Apollonius, Callimachus, Nicander, Aratus and others in purple passages of his own, but that so many of his techniques of composition and allusion, and—as this paper will demonstrate—his formal evocation of certain styles of writing, are thoroughly Hellenistic. So the first thing that is needed is an exploration of the various ways in which imperial writers respond to the masters of the high Hellenistic period, and their successors: is Dionysius a representative of a special and distinctive strain in imperial poetics, or is he a particular instance of something more multiform and complex?

A new analysis of the effects of the Asian crisis of 1997 on emergent markets

This work is devoted to the study of the Asian crisis of 1997, and its consequences on emerging markets. We have done so by means of a phase transition model. We have analyzed the crashes on leading indices of Hong Kong (HSI), Turkey (XU100), Mexico (MMX), Brazil (BOVESPA) and Argentina (MERVAL). We were able to obtain optimum values for the critical date, corresponding to the most probable date of the crash. The estimation of the critical date was excellent except for the MERVAL index; this improvement is due to a previous analysis of the parameters involved. We only used data from before the true crash date in order to obtain the predicted critical date. This article's conclusions are largely obtained via ad hoc empirical methods.