Lost Events Research Articles

Margaret Garner and the Second Tear

Margaret Garner and the Second Tear Catherine Gunther Kodat (bio) Margaret Garner, an opera. Music by Richard Danielpour; libretto by Toni Morrison. World première at Michigan Opera Theatre May 7, 2005. New production by the New York City Opera performed on various dates in September 2007. I wanted that haunting not to be really a suggestion of being bedeviled by the past, but to have it be incarnate, to have it actually happen that a person enters your world who is in fact—you believe, at any rate—the dead returned, and you get a second chance, a chance to do it right. Of course, you do it wrong again. —Toni Morrison Kitsch causes two tears to flow in quick succession. The first tear says: How nice to see children running on the grass! The second tear says: How nice to be moved, together with all mankind, by children running on the grass! It is the second tear that makes kitsch kitsch. —Milan Kundera Before the 1987 appearance of Toni Morrison's novel Beloved, most Americans had never heard of Margaret Garner, the fugitive slave from Kentucky who, in 1856, killed one of her children as she and her family were about to be recaptured in Ohio. It would not be correct to say that Garner became a household name as a consequence of the critical and popular acclaim that greeted Beloved, but her story, if not her identity, certainly became better known than it had been before the novel—for it was Garner's murder of her two-year-old daughter Mary that gave Morrison the idea for Beloved. Morrison has always acknowledged this inspiration, but in interviews published when the novel first appeared she was careful to note that Beloved was engaged in a project rather different from the recovery of a specific lost event. Beloved's reach extends well beyond the bounds of conventional historical fiction, taking both the murder and the task of its narration as opportunities to pose fraught questions about U.S. racial history, memory, trauma, and guilt, and to acknowledge that making art out of this volatile material is a hazardous [End Page 159] endeavor. As Morrison frequently pointed out, Beloved was an invention, and, as her blending of modernist literary techniques with plot devices drawn from gothic fiction makes clear, she had little interest in producing a fictionalized account of a historical figure or event in the manner of Truman Capote's In Cold Blood or Thomas Flanagan's The Year of the French.1 In fact, it would not be incorrect to say that it is precisely the disappearance of Margaret Garner's case from our national memory that matters most to Beloved, given its preoccupation with the difficulties of recollection and representation—of "passing on," as the novel's closing pages put it. Nevertheless (and perhaps unsurprisingly), the years since the appearance of Beloved have seen several efforts to recover the lost history of this "Modern Medea" (as Garner was styled in Kentucky artist Thomas Satterwhite Noble's 1867 painting of the murder). On the face of it, there were good reasons to make the attempt. Though practically unknown to most in the United States, black and white, for much of the twentieth century, Margaret Garner was extremely famous in her lifetime, an abolitionist cause célèbre and the inspiration for scores of essays, poems, pamphlets, and engravings that cast her variously as a nineteenth-century Medea, Virginius, or Mithridates. But as the appeals to characters from antiquity hint, Garner's murder came to the public via prefabricated narrative forms. Almost certainly as a function of its deeply unsettling aspects (some of them acknowledged only indirectly to this day), Margaret Garner's slaying of her daughter was never granted the dignity of a singular human event, an irreproducible meeting of impersonal historical forces with individual circumstance. On the contrary, the story of the woman who murdered a child rather than see it returned to slavery—for so her act was immediately interpreted in the press—was viewed by mid-nineteenth-century journalists, poets, poetasters, and visual artists (proslavery and abolitionist alike) as bringing to life ancient and familiar...

Global analysis of exon creation versus loss and the role of alternative splicing in 17 vertebrate genomes

Association of alternative splicing (AS) with accelerated rates of exon evolution in some organisms has recently aroused widespread interest in its role in evolution of eukaryotic gene structure. Previous studies were limited to analysis of exon creation or lost events in mouse and/or human only. Our multigenome approach provides a way for (1) distinguishing creation and loss events on the large scale; (2) uncovering details of the evolutionary mechanisms involved; (3) estimating the corresponding rates over a wide range of evolutionary times and organisms; and (4) assessing the impact of AS on those evolutionary rates. We use previously unpublished independent analyses of alternative splicing in five species (human, mouse, dog, cow, and zebrafish) from the ASAP database combined with genomewide multiple alignment of 17 genomes to analyze exon creation and loss of both constitutively and alternatively spliced exons in mammals, fish, and birds. Our analysis provides a comprehensive database of exon creation and loss events over 360 million years of vertebrate evolution, including tens of thousands of alternative and constitutive exons. We find that exon inclusion level is inversely related to the rate of exon creation. In addition, we provide a detailed in-depth analysis of mechanisms of exon creation and loss, which suggests that a large fraction of nonrepetitive created exons are results of ab initio creation from purely intronic sequences. Our data indicate an important role for alternative splicing in creation of new exons and provide a useful novel database resource for future genome evolution research.

Paleomagnetism of Ar‐Ar dated lava flows from the Ceboruco‐San Pedro volcanic field (western Mexico): Evidence for the Matuyama‐Brunhes transition precursor and a fully reversed geomagnetic event in the Brunhes chron

We report a detailed paleomagnetic and rock magnetic study of 17 independent lava flows belonging to the Trans‐Mexican Volcanic Belt; 175 oriented samples were collected in the Ceboruco‐San Pedro volcanic field. These sites were previously dated by means of a state‐of‐the‐art 40Ar‐39Ar geochronological method and span from 819 to 2 ka. Rock magnetic experiments, which included continuous susceptibility and hysteresis measurements, point to simple magnetic mineralogy. In most cases, the remanence is carried by Ti‐poor titanomagnetite of pseudosingle‐domain magnetic structure. Fourteen flows give normal magnetic polarities, while two are reversely magnetized; only one cooling unit yields intermediate paleodirections. The paleodirections of the flow dated at 819 ± 25 ka correspond to a VGP latitude of 18°N. This anomalous field behavior apparently recorded prior to the Matuyama‐Brunhes (M‐B) reversal may coincide with the transitionally magnetized lavas on La Palma, Canary Islands (40Ar‐39Ar age of 822.2 ± 8.7 ka), and with an event featured in several marine sediment records. Thus this geomagnetic event, defined as M‐B precursor, is probably global in extent. Two independent lava flows, dated at 623 ± 91 and 614 ± 16 ka, yield reverse paleodirections. Age uncertainties make it difficult to claim the discovery of a new geomagnetic event. It is possible that these lavas erupted during the worldwide observable Big Lost event (40Ar‐39Ar age of 580.2 ± 7.8 ka), which has probably been longer and more complex than it is generally believed for geomagnetic excursions.

Ar/Ar ages from transitionally magnetized lavas on La Palma, Canary Islands, and the geomagnetic instability timescale

A detailed study of 43 lava flows comprising two stratigraphic sequences exposed along the north and south walls of Barranco de los Tilos on the island of La Palma, Canary Islands, reveals a complex, temporally segmented record of geodynamo behavior that contains no less than three distinct geomagnetic events. The Matuyama‐Brunhes (M‐B) reversal is recorded in five transitionally magnetized lava flows from the north (TN) section. The isochrons obtained from three of the lower four M‐B lavas are defined by 14 incremental heating experiments that, together with a previous age determination, yielded a weighted mean of 798.4 ± 6.2 ka (all uncertainties ±2σ). In addition, a 780.3 ± 10.3 ka isochron was determined for the overlying transitionally magnetized flow, indicating that it was erupted during a distinctly younger portion of the transition. Near the base of the south (TS) section one finds a sequence of weakly magnetized flows associated with virtual geomagnetic pole (VGP) positions in the southwest Indian Ocean between latitudes 56°S and 65°S, suggesting instability of the geomagnetic field beyond that of typical secular variation. 40Ar/39Ar isochrons from three of these flows, defined by 11 separate incremental heating experiments, gave a weighted mean of 822.2 ± 8.7 ka. This anomalous field behavior recorded 24 ± 11 kyr prior to the M‐B reversal may coincide with an event featured in several marine sediment records. Directly above two normal polarity flows (40Ar/39Ar isochrons of 751.9 ± 18.1 ka and 675.0 ± 15.7 ka) are nine transitionally magnetized lavas having magnetization directions associated with low to midlatitude VGPs spanning 23°–60°N. These flows are then capped by a single flow possessing normal polarity. Based on 12 incremental heating experiments, 40Ar/39Ar isochrons of five of these nine lavas, along with the uppermost flow, gave a weighted mean age of 580.2 ± 7.8 ka for this period of transitional to normal field behavior. From these same transitional lavas, Quidelleur et al. [1999] reported three unspiked K‐Ar ages with a weighted mean of 602 ± 24 ka and proposed a new event called the “La Palma” excursion. However, the 40Ar/39Ar age presented here is three times more precise than the K‐Ar age and is indistinguishable at the 95% confidence level from the 40Ar/39Ar age of a lava from the Snake River Plain, Idaho, that originally defined the Big Lost event. Transitional field behavior of similar age observed in astronomically dated marine cores further establishes that the Big Lost event recorded at La Palma was indeed global in extent. Rigorous temporal and geomagnetic constraints for several additional periods of geomagnetic field instability during the last several million years will comprise a geomagnetic instability timescale that can be factored confidently into models of the dynamo process.

The X-Ray/Gamma-ray spectrometer on the near Earth Asteroid Rendezvous mission

The X-ray/Gamma-ray Spectrometer on the Near Earth Asteroid Rendezvous spacecraft is a remote sensing instrument designed to develop elemental composition maps of the surface of the asteroid 433 Eros. This mapping operation will occur during about 10 months of orbital operations commencing in early 1999. Solar excited x-ray fluorescence in the 1 to 10 keV range will be used to measure the surface abundances of Mg, Al, Si, Ca, Ti, and Fe with spatial resolutions down to 2 km. Characteristic gamma-ray emissions in the 0.1 to 10 Mev range will be used to measure cosmic-ray excited elements O, Si, Fe, H and naturally radioactive elements K, Th, U to a depth of order 10 cm. The asteroid pointing portion of the x-ray spectrometer consists of three gas-filled proportional counters with an energy resolution of 850 eV full-width at half-maximum (FWHM) @ 5.9 keV. Two sunward looking x-ray detectors monitor the incident solar flux, one of which is the first flight of a new, miniature Si-PIN solid-state detector which achieves 600 eV FWHM @ 5.9 keV. The gamma-ray spectrometer consists of a NaI(Tl) scintillator situated in an active Bismuth Germanate (BGO) cup shield which confines the field of view, eliminates the need for a costly boom, and enables recovery of lost events in the central detector. The NaI(Tl) and BGO detectors achieve energy resolutions of 8.7% and 14% FWHM @ 0.662 MeV, respectively. A data processing unit using an RTX2010 provides the spacecraft interface and produces 256-channel spectra for x-ray detectors and 1024-channel spectra for integral, coincident, and anticoincident gamma-ray modes. We present an overview of the instrument and discuss design parameters and trade-offs.

The Effect of Live Time in Components of a Positron Tomograph on Image Quantification

The livetime of several PET systems has been characterized in terms of a paralysing time after each coincidence event. If part of the deadtime is due to light collection and position encoding in a crystal array, the system deadtime is a function of the singles-to-coincidence-count ratio which in turn depends on the object size and radioisotope distribution. In this case it is necessary to make an independent measurement of the detector livetime. Since both detectors must be live to record a coincidence event, the detector contribution to system livetime is more pronounced in tomographs using position encoding schemes. Since dead detectors cannot contribute random events, the randoms rate will be less if deadtime is caused by the detectors rather than by the coincidence circuit. After analysing the sources of lost events at each stage in the encoding process we propose that, rather than using empi rical estimates, hardware be used to compute these losses.

One-coordinate X-ray detector

One-coordinate X-ray detector OD-1 has 1024 channels with a channel size of 0.1 mm. The counting rate of good events at the 50% level of lost events is 150 kHz. The detector can be used for multisnap recording of X-ray pictures, that allows to obtain the radiographs for moving objects.