3,986 research outputs found
What, if anything, is a Paratrochamminoides? A key to the morphology of the Cretaceous to Cenozoic species of Conglophragmium and Paratrochamminoides (Foraminifera)
We present a review of the current taxonomical status of the genus Paratrochamminoides Soliman,
1972. We recognise five main subgroups of this genus based upon the following modes of coiling:
trochospiral, streptospiral, glomospiral, triloculine or milioline, and thalmannamminiform. Species
that display streptospiral coiling and an interiomarginal aperture are placed in the genus
Conglophragmium BermĂșdez & Rivero, 1963, whereas the genus Paratrochamminoides is here
understood to encompass all other coiling modes. The morphological characters of 23 named and
unnamed species that we recognise as belonging to Paratrochamminoides and Conglophragmium are
presented in tabular form. Of these, 22 are considered here to be valid species. Emended descriptions
are provided for both genera, and diagnoses are given for each of the species
Tubular agglutinated foraminifera as indicators of organic carbon flux
The dimensions of tubular agglutinated foraminifera such as Rhizammina and Rhabdammina respond
in a predictable manner to changes in the flux of organic carbon to the sea floor. In both the modern
western North Atlantic and in an ancient example (the K/T boundary in Gubbio), the slender,
finely-grained tubes (<100 ÎŒm diameter) dominate in oligotrophic regimes, whereas in eutrophic
regimes the abundance of tubes is higher, and the mean and standard deviation of the tube
diameter increases. Large tubes (> 500 ÎŒm) are present only when organic flux is comparatively
high. Although our observations are at present not directly calibrated to primary productivity
levels, we maintain that the potential for using tubular agglutinated foraminifera does exist
Upper Cretaceous, K/T boundary, and Paleocene agglutinated foraminifers from Hole 959D (CĂŽte d'Ivoire-Ghana Transform Margin)
Upper Cretaceous agglutinated foraminifer assemblages from Hole 959D of Ocean Drilling Program (ODP) Leg 159, CĂŽte dâIvoire-Ghana Transform Margin, reflect the subsidence history and paleoceanography of the widening equatorial Atlantic gateway. Five benthic foraminifer assemblage types are recognized: (1) Santonian and the lowermost Campanian assemblages (Cores 159-959D-65R and 64R) are characterized by the occurrence of bathyal calcareous benthic foraminifers with an increasing proportion of agglutinated foraminifers. The disappearance of calcareous foraminifers and assemblages exclusively composed of organically cemented agglutinated forms in Section 159-959D-65R-3 reflects the subsidence of the seafloor below the calcite compensation depth (CCD); (2) lower Campanian "biofacies B" assemblages (Cores 159-959D-63R through 61R) are exclusively composed of low-diversity agglutinated foraminifers, accompanied by abundant and occasionally well-preserved radiolarian assemblages; (3) middle Campanian to upper Maastrichtian deposits (Cores 159-959D-59R through 49R) contain an exclusively agglutinated Rzehakina epigona biofacies, which is well-known from middle to deep bathyal sites along the North Atlantic margins; (4) a change in agglutinated foraminifer assemblage composition toward morphologies commonly observed in present infaunal habitats and the common occurrence of the presumably infaunal genus Spiroplectammina are observed in Core 159-959D-48R. This change in agglutinated foraminifer assemblages corresponds to the Tethyan early Paleocene "Spiroplectammina event;" (5) a diversified Paleocene "Lizard Springs type" assemblage is characterized by several diverse Rzehakina, Saccamina, and Haplophragmoides species. Assemblages from Cores 159-959D-48R through 44R display high species diversity and reflect the deepest (lower bathyal to upper abyssal) paleobathymetry.
Ranges of agglutinated foraminifer marker species and occurrences of paleoceanographic events within this biostratigraphic framework are almost identical to those observed in the North Atlantic, in the Western Tethys, and along the conjugate Brazilian margin. These observations lead us to confirm that a deep-water circulation system common to the North and South Atlantic has been active at least since the Santonian
Determination of the Io heat flow. 1: Eclipse observations
The thermal emission from Io during eclipse by Jupiter yields data from which the total thermal flux from the volcanoes on the satellite surface can be estimated. Thermal infrared observations in spectral bands between 3.5 and 30 microns of five Io eclipse reappearances and one eclipse disappearance are reported and discussed. The thermal emission of the volcanoes which occurs almost all of the time was determined from the Io heat flux data. The thermal observations of Io are discussed with respect to previous thermophysical theories
When Do Stop-Loss Rules Stop Losses?
Stop-loss rules-predetermined policies that reduce a portfolio's exposure after reaching a certain threshold of cumulative losses-are commonly used by retail and institutional in- vestors to manage the risks of their investments, but have also been viewed with some skep- ticism by critics who question their e±cacy. In this paper, we develop a simple framework for measuring the impact of stop-loss rules on the expected return and volatility of an arbitrary portfolio strategy, and derive conditions under which stop-loss rules add or subtract value to that portfolio strategy. We show that under the Random Walk Hypothesis, simple 0/1 stop-loss rules always decrease a strategy's expected return, but in the presence of momen- tum, stop-loss rules can add value. To illustrate the practical relevance of our framework, we provide an empirical analysis of a stop-loss policy applied to a buy-and-hold strategy in U.S. equities, where the stop-loss asset is U.S. long-term government bonds. Using monthly returns data from January 1950 to December 2004, we find that certain stop-loss rules add 50 to 100 basis points per month to the buy-and-hold portfolio during stop-out periods. By computing performance measures for several price processes, including a new regime- switching model that implies periodic "flights-to-quality", we provide a possible explanation for our empirical results and connections to the behavioral finance literature.Investments; Portfolio Management; Risk Management; Performance Attribution; Behavioral Finance
Agglutinated foraminifera from neritic to bathyal facies in the Palaeogene of Spitsbergen and the Barents Sea
Late Palaeocene to Early Eocene foraminiferal assemblages have been analysed from an
exploratory well (7119/7-1) drilled in the TromsĂž Basin (southwestern Barents Sea) and from
two onshore sections, Basilikaelva and Kovalskifjella, exposed in the Central Tertiary Basin of
Spitsbergen. The assemblages reveal marked differences in taxonomic composition and
diversity, reflecting inner neritic to middle bathyal conditions. Within this depth range, four
foraminiferal biofacies (FB) are distinguished:
FB 1 occurs in the Kolthoffberget Member (of the Firkanten Formation, Late Palaeocene)
sampled in the Basilikaelva section. The member consists of interbedded shales, siltstones
and sandstones deposited in a transitional delta front - prodelta environment, according to
current sedimentological interpretation. The foraminiferal assemblages are entirely
agglutinated, show extremely low species diversities and strong dominance of
Reticulophragmium arcticum followed by Labrospira aff. turbida.
FB 2 is recognised in the Basilika Formation (Late Palaeocene) exposed in the
Kovalskifjella section. The formation consists of silty claystones deposited in a prodelta shelf
setting. The foraminiferal assemblages show an increased species diversity, and consist
mainly of agglutinated taxa with a strongly subordinate calcareous component. The two
most abundant species are R. arcticum and L. aff. turbida. Species of Verneuilinoides and
Trochammina occur in significant numbers while tubular taxa are rare.
FB 3 is found in the Lower Eocene clay interval composing the upper part of the Torsk
Formation in well 7119/7-1. It contains entirely agglutinated assemblages with
comparatively high diversities. The dominant species are Recurvoides aff. turbinatus and
Budashevaella multicamerata, while Reticulophragmium amplectens is typical and common in
these strata. Tubular forms referred to Rhizammina occur locally in significant quantities. The
diversity and composition of the assemblages suggest an outer neritic to upper bathyal
environment.
FB 4 is developed in Palaeocene claystones comprising the lower part of the Torsk
Formation in well 7119/7-1. In this interval the species diversity, as well as the frequency of
tubular forms (referred to Rhizammina, Bathysiphon and Hyperammina) attains maximum
values. Other common to dominant taxa include Spiroplectammina spectabilis,
Haplophragmoides walteri, Ammosphaeroidina pseudopauciloculata, and Recurvoides sp. These
wholly agglutinated assemblages are interpreted as reflecting upper to middle bathyal
conditions
Ash grains of the 1991 Mt. Pinatubo eruption as a tracer in Rose Bengal stained deep sea agglutinated foraminifera: How old is Freddy?
The use of volcanic ash particles (including dark-coloured grains) by agglutinated foraminifera that survived the 1991 eruption of Mt Pinatubo volcano provides a useful tracer to help determine growth rates and longevity in the deep sea. In the case of a specimen of Cyclammina pusilla Brady, the rate of chamber addition in this Rose Bengal stained sub-adult individual is three chambers over a timespan of five and one-half years
Conclude to Exclude: The Exclusionary Rule\u27s Role in Civil Forfeiture Proceedings
The United States Supreme Court established the exclusionary rule in order to deter law enforcement officers from conducting illegal searches and seizures. By excluding illegally seized evidence, the Court looked to provide American citizens with a remedy to uphold their Fourth Amendment rights. Traditionally, the exclusionary rule excluded only illegally obtained evidence in criminal proceedings. In One 1958 Plymouth Sedan v. Commonwealth of Pennsylvania, however, the Court applied the exclusionary rule to civil forfeiture proceedings because the forfeiture statute was quasi-criminal in nature: like a criminal proceeding, its object was to penalize the commission of an offense.
The forfeiture statute upon which the Plymouth decision was based has since become inapplicable to modern forfeiture proceedings, thus bringing Plymouth\u27s viability into question. Additionally, following Plymouth, the Court adopted a balancing test that weighs the benefits of deterrence against the costs to society in determining whether to apply the exclusionary rule. The Court\u27s cost-benefit analysis, however, has never extended the exclusionary rule beyond the criminal trial context. Because of this, lower state and federal courts have questioned which approach-- Plymouth or the cost-benefit analysis--they should apply in the context of civil forfeiture proceedings.
In United States v. Marrocco, a recent Seventh Circuit case, Judge Easterbrook distinguished Plymouth, stating that the forfeiture statute before the court was civil and not intended as punishment for the commission of a crime. In Marrocco, the forfeiture proceeding did not necessitate a conviction of a criminal offense. Thus, it would appear that the Seventh Circuit would employ the cost-benefit analysis to determine whether the exclusionary rule would be applied in the context of civil forfeiture. The evolution of forfeiture statutes since Plymouth, combined with the Supreme Court\u27s cost-benefit analysis--which has never extended the exclusionary rule beyond the criminal trial context--poses a serious threat to the application of the exclusionary rule in civil forfeiture proceedings. In weighing the benefits of deterrence against the costs, the Supreme Court has consistently focused on criminal prosecution as the sole objective of law enforcement; however, the changing objectives of law enforcement agencies have led forfeiture to become ingrained into mainstream police practices. Because of this, regardless of whether Plymouth is overturned or the cost-benefit analysis is used, the exclusionary rule should be applied because civil forfeiture\u27s unique role in modern policing would result in a high level of deterrence that would not be outweighed by the minimal costs associated with the relatively government-friendly proceeding
Conclude to Exclude: The Exclusionary Rule\u27s Role in Civil Forfeiture Proceedings
The United States Supreme Court established the exclusionary rule in order to deter law enforcement officers from conducting illegal searches and seizures. By excluding illegally seized evidence, the Court looked to provide American citizens with a remedy to uphold their Fourth Amendment rights. Traditionally, the exclusionary rule excluded only illegally obtained evidence in criminal proceedings. In One 1958 Plymouth Sedan v. Commonwealth of Pennsylvania, however, the Court applied the exclusionary rule to civil forfeiture proceedings because the forfeiture statute was quasi-criminal in nature: like a criminal proceeding, its object was to penalize the commission of an offense.
The forfeiture statute upon which the Plymouth decision was based has since become inapplicable to modern forfeiture proceedings, thus bringing Plymouth\u27s viability into question. Additionally, following Plymouth, the Court adopted a balancing test that weighs the benefits of deterrence against the costs to society in determining whether to apply the exclusionary rule. The Court\u27s cost-benefit analysis, however, has never extended the exclusionary rule beyond the criminal trial context. Because of this, lower state and federal courts have questioned which approach-- Plymouth or the cost-benefit analysis--they should apply in the context of civil forfeiture proceedings.
In United States v. Marrocco, a recent Seventh Circuit case, Judge Easterbrook distinguished Plymouth, stating that the forfeiture statute before the court was civil and not intended as punishment for the commission of a crime. In Marrocco, the forfeiture proceeding did not necessitate a conviction of a criminal offense. Thus, it would appear that the Seventh Circuit would employ the cost-benefit analysis to determine whether the exclusionary rule would be applied in the context of civil forfeiture. The evolution of forfeiture statutes since Plymouth, combined with the Supreme Court\u27s cost-benefit analysis--which has never extended the exclusionary rule beyond the criminal trial context--poses a serious threat to the application of the exclusionary rule in civil forfeiture proceedings. In weighing the benefits of deterrence against the costs, the Supreme Court has consistently focused on criminal prosecution as the sole objective of law enforcement; however, the changing objectives of law enforcement agencies have led forfeiture to become ingrained into mainstream police practices. Because of this, regardless of whether Plymouth is overturned or the cost-benefit analysis is used, the exclusionary rule should be applied because civil forfeiture\u27s unique role in modern policing would result in a high level of deterrence that would not be outweighed by the minimal costs associated with the relatively government-friendly proceeding
Exploring the diffeomorphism invariant Hilbert space of a scalar field
As a toy model for the implementation of the diffeomorphism constraint, the
interpretation of the resulting states, and the treatment of ordering
ambiguities in loop quantum gravity, we consider the Hilbert space of spatially
diffeomorphism invariant states for a scalar field. We give a very explicit
formula for the scalar product on this space, and discuss its structure.
Then we turn to the quantization of a certain class of diffeomorphism
invariant quantities on that space, and discuss in detail the ordering issues
involved. On a technical level these issues bear some similarity to those
encountered in full loop quantum gravity.Comment: 20 pages, no figures; v3: corrected typos, added reference, some
clarifications added; version as published in CQ
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