254 research outputs found
Enumeration of distinct mechanically stable disk packings in small systems
We create mechanically stable (MS) packings of bidisperse disks using an
algorithm in which we successively grow or shrink soft repulsive disks followed
by energy minimization until the overlaps are vanishingly small. We focus on
small systems because this enables us to enumerate nearly all distinct MS
packings. We measure the probability to obtain a MS packing at packing fraction
and find several notable results. First, the probability is highly
nonuniform. When averaged over narrow packing fraction intervals, the most
probable MS packing occurs at the highest and the probability decays
exponentially with decreasing . Even more striking, within each
packing-fraction interval, the probability can vary by many orders of
magnitude. By using two different packing-generation protocols, we show that
these results are robust and the packing frequencies do not change
qualitatively with different protocols.Comment: 4 pages, 3 figures, Conference Proceedings for X International
Workshop on Disordered System
The role of the right temporoparietal junction in perceptual conflict: detection or resolution?
The right temporoparietal junction (rTPJ) is a polysensory cortical area that plays a key role in perception and awareness. Neuroimaging evidence shows activation of rTPJ in intersensory and sensorimotor conflict situations, but it remains unclear whether this activity reflects detection or resolution of such conflicts. To address this question, we manipulated the relationship between touch and vision using the so-called mirror-box illusion. Participants' hands lay on either side of a mirror, which occluded their left hand and reflected their right hand, but created the illusion that they were looking directly at their left hand. The experimenter simultaneously touched either the middle (D3) or the ring finger (D4) of each hand. Participants judged, which finger was touched on their occluded left hand. The visual stimulus corresponding to the touch on the right hand was therefore either congruent (same finger as touch) or incongruent (different finger from touch) with the task-relevant touch on the left hand. Single-pulse transcranial magnetic stimulation (TMS) was delivered to the rTPJ immediately after touch. Accuracy in localizing the left touch was worse for D4 than for D3, particularly when visual stimulation was incongruent. However, following TMS, accuracy improved selectively for D4 in incongruent trials, suggesting that the effects of the conflicting visual information were reduced. These findings suggest a role of rTPJ in detecting, rather than resolving, intersensory conflict
The Formation and Evolution of the First Massive Black Holes
The first massive astrophysical black holes likely formed at high redshifts
(z>10) at the centers of low mass (~10^6 Msun) dark matter concentrations.
These black holes grow by mergers and gas accretion, evolve into the population
of bright quasars observed at lower redshifts, and eventually leave the
supermassive black hole remnants that are ubiquitous at the centers of galaxies
in the nearby universe. The astrophysical processes responsible for the
formation of the earliest seed black holes are poorly understood. The purpose
of this review is threefold: (1) to describe theoretical expectations for the
formation and growth of the earliest black holes within the general paradigm of
hierarchical cold dark matter cosmologies, (2) to summarize several relevant
recent observations that have implications for the formation of the earliest
black holes, and (3) to look into the future and assess the power of
forthcoming observations to probe the physics of the first active galactic
nuclei.Comment: 39 pages, review for "Supermassive Black Holes in the Distant
Universe", Ed. A. J. Barger, Kluwer Academic Publisher
Gravitational Radiation from Post-Newtonian Sources and Inspiralling Compact Binaries
The article reviews the current status of a theoretical approach to the
problem of the emission of gravitational waves by isolated systems in the
context of general relativity. Part A of the article deals with general
post-Newtonian sources. The exterior field of the source is investigated by
means of a combination of analytic post-Minkowskian and multipolar
approximations. The physical observables in the far-zone of the source are
described by a specific set of radiative multipole moments. By matching the
exterior solution to the metric of the post-Newtonian source in the near-zone
we obtain the explicit expressions of the source multipole moments. The
relationships between the radiative and source moments involve many non-linear
multipole interactions, among them those associated with the tails (and
tails-of-tails) of gravitational waves. Part B of the article is devoted to the
application to compact binary systems. We present the equations of binary
motion, and the associated Lagrangian and Hamiltonian, at the third
post-Newtonian (3PN) order beyond the Newtonian acceleration. The
gravitational-wave energy flux, taking consistently into account the
relativistic corrections in the binary moments as well as the various tail
effects, is derived through 3.5PN order with respect to the quadrupole
formalism. The binary's orbital phase, whose prior knowledge is crucial for
searching and analyzing the signals from inspiralling compact binaries, is
deduced from an energy balance argument.Comment: 109 pages, 1 figure; this version is an update of the Living Review
article originally published in 2002; available on-line at
http://www.livingreviews.org
The quest for the solar g modes
Solar gravity modes (or g modes) -- oscillations of the solar interior for
which buoyancy acts as the restoring force -- have the potential to provide
unprecedented inference on the structure and dynamics of the solar core,
inference that is not possible with the well observed acoustic modes (or p
modes). The high amplitude of the g-mode eigenfunctions in the core and the
evanesence of the modes in the convection zone make the modes particularly
sensitive to the physical and dynamical conditions in the core. Owing to the
existence of the convection zone, the g modes have very low amplitudes at
photospheric levels, which makes the modes extremely hard to detect. In this
paper, we review the current state of play regarding attempts to detect g
modes. We review the theory of g modes, including theoretical estimation of the
g-mode frequencies, amplitudes and damping rates. Then we go on to discuss the
techniques that have been used to try to detect g modes. We review results in
the literature, and finish by looking to the future, and the potential advances
that can be made -- from both data and data-analysis perspectives -- to give
unambiguous detections of individual g modes. The review ends by concluding
that, at the time of writing, there is indeed a consensus amongst the authors
that there is currently no undisputed detection of solar g modes.Comment: 71 pages, 18 figures, accepted by Astronomy and Astrophysics Revie
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Medicinal plants used by women in Mecca: urban, Muslim and gendered knowledge
Background: This study explores medicinal plant knowledge and use among Muslim women in the city of Mecca,
Saudi Arabia. Ethnobotanical research in the region has focused on rural populations and male herbal healers in
cities, and based on these few studies, it is suggested that medicinal plant knowledge may be eroding. Here, we
document lay, female knowledge of medicinal plants in an urban centre, interpreting findings in the light of the
growing field of urban ethnobotany and gendered knowledge and in an Islamic context.
Methods: Free-listing, structured and semi-structured interviews were used to document the extent of medicinal
plant knowledge among 32 Meccan women. Vernacular names, modes of preparation and application, intended
therapeutic use and emic toxicological remarks were recorded. Women were asked where they learnt about
medicinal plants and if and when they preferred using medicinal plants over biomedical resources. Prior informed consent was always obtained. We compared the list of medicinal plants used by these Meccan women with medicinal plants previously documented in published literature.
Results: One hundred eighteen vernacular names were collected, corresponding to approximately 110 plants, including one algae. Of these, 95 were identified at the species level and 39 (41%) had not been previously cited in Saudi Arabian medicinal plant literature. Almost one half of the plants cited are food and flavouring plants. Meccan women interviewed learn about medicinal plants from their social network, mass media and written sources, and combine biomedical and medicinal plant health care. However, younger women more often prefer biomedical resources and learn from written sources and mass media.
Conclusions: The fairly small number of interviews conducted in this study was sufficient to reveal the singular body of medicinal plant knowledge held by women in Mecca and applied to treat common ailments. Plant availability in local shops and markets and inclusion in religious texts seem to shape the botanical diversity used by the Meccan women interviewed, and the use of foods and spices medicinally could be a global feature of urban ethnobotany. Ethnobotanical knowledge among women in Islamic communities may be changing due to access to mass media and biomedicine. We recognise the lack of documentation of the diversity of medicinal plant knowledge in the Arabian Peninsula and an opportunity to better understand gendered urban and rural knowledge
Rituximab in B-Cell Hematologic Malignancies: A Review of 20 Years of Clinical Experience
Rituximab is a human/murine, chimeric anti-CD20 monoclonal antibody with established efficacy, and a favorable and well-defined safety profile in patients with various CD20-expressing lymphoid malignancies, including indolent and aggressive forms of B-cell non-Hodgkin lymphoma. Since its first approval 20 years ago, intravenously administered rituximab has revolutionized the treatment of B-cell malignancies and has become a standard component of care for follicular lymphoma, diffuse large B-cell lymphoma, chronic lymphocytic leukemia, and mantle cell lymphoma. For all of these diseases, clinical trials have demonstrated that rituximab not only prolongs the time to disease progression but also extends overall survival. Efficacy benefits have also been shown in patients with marginal zone lymphoma and in more aggressive diseases such as Burkitt lymphoma. Although the proven clinical efficacy and success of rituximab has led to the development of other anti-CD20 monoclonal antibodies in recent years (e.g., obinutuzumab, ofatumumab, veltuzumab, and ocrelizumab), rituximab is likely to maintain a position within the therapeutic armamentarium because it is well established with a long history of successful clinical use. Furthermore, a subcutaneous formulation of the drug has been approved both in the EU and in the USA for the treatment of B-cell malignancies. Using the wealth of data published on rituximab during the last two decades, we review the preclinical development of rituximab and the clinical experience gained in the treatment of hematologic B-cell malignancies, with a focus on the well-established intravenous route of administration. This article is a companion paper to A. Davies, et al., which is also published in this issue
FCR (Fludarabine, Cyclophosphamide, Rituximab) regimen followed by 90yttrium ibritumomab tiuxetan consolidation for the treatment of relapsed grades 1 and 2 follicular lymphoma: a report of 9 cases
<p>Abstract</p> <p>Background</p> <p>This retrospective analysis is focused on the efficacy and safety of radioimmunotherapy (RIT) with Zevalin<sup>® </sup>in nine patients with recurrent follicular lymphoma (FL) who were treated in a consolidation setting after having achieved complete remission or partial remission with FCR.</p> <p>Methods</p> <p>The median age was 63 yrs (range 46-77), all patients were relapsed with histologically confirmed CD20-positive (grade 1 or 2) FL, at relapse they received FCR every 28 days: F (25 mg/m<sup>2</sup>x 3 days), C (1 gr/m<sup>2 </sup>day 1) and R (375 mg/m<sup>2 </sup>day 4) for 4 cycles. Who achieved at least a partial remission, with < 25% bone marrow involvement, was treated with <sup>90</sup>Yttrium Ibritumomab Tiuxetan 11.1 or 14.8 MBq/Kg up to a maximum dose 1184 MBq, at 3 months after the completion of FCR. The patients underwent a further restaging at 12 weeks after <sup>90</sup>Y-RIT with total body CT scan, FDG-PET/CT and bilateral bone marrow biopsy.</p> <p>Results</p> <p>Nine patients have completed the treatment: FCR followed by <sup>90</sup>Y-RIT (6 patients at 14.8 MBq/Kg, 3 patients at 11.1 MBq/Kg). After FCR 7 patients obtained CR and 2 PR; after <sup>90</sup>Y-RIT two patients in PR converted to CR 12 weeks later. With median follow up of 34 months (range 13-50) the current analysis has shown that overall survival (OS) is 89% at 2 years, 76% at 3 years and 61% at 4 years. The most common grade 3 or 4 adverse events were hematologic, one patient developed herpes zoster infection after 8 months following valacyclovir discontinuation; another patient developed fungal infection.</p> <p>Conclusions</p> <p>Our experience indicate feasibility, tolerability and efficacy of FCR regimen followed by <sup>90</sup>Y-RIT in patients relapsed with grades 1 and 2 FL with no unexpected toxicities. A longer follow up and a larger number of patients with relapsed grades 1 and 2 FL are required to determine the impact of this regimen on long-term duration of response and PFS.</p
Contrasting effects of hemiparasites on ecosystem processes: can positive litter effects offset the negative effects of parasitism?
Hemiparasites are known to influence community structure and ecosystem functioning, but the underlying mechanisms are not well studied. Variation in the impacts of hemiparasites on diversity and production could be due to the difference in the relative strength of two interacting pathways: direct negative effects of parasitism and positive effects on N availability via litter. Strong effects of parasitism should result in substantial changes in diversity and declines in productivity. Conversely, strong litter effects should result in minor changes in diversity and increased productivity. We conducted field-based surveys to determine the association of Castillejaoccidentalis with diversity and productivity in the alpine tundra. To examine litter effects, we compared the decomposition of Castilleja litter with litter of four other abundant plant species, and examined the decomposition of those four species when mixed with Castilleja. Castilleja was associated with minor changes in diversity but almost a twofold increase in productivity and greater foliar N in co-occurring species. Our decomposition trials suggest litter effects are due to both the rapid N loss of Castilleja litter and the effects of mixing Castilleja litter with co-occurring species. Castilleja produces litter that accelerates decomposition in the alpine tundra, which could accelerate the slow N cycle and boost productivity. We speculate that these positive effects of litter outweigh the effects of parasitism in nutrient-poor systems with long-lived hemiparasites. Determining the relative importance of parasitism and litter effects of this functional group is crucial to understand the strong but variable roles hemiparasites play in affecting community structure and ecosystem processes
Explaining variability in ciclosporin exposure in adult kidney transplant recipients
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