1,514 research outputs found
Witnessing the active assembly phase of massive galaxies since z = 1
We present an analysis of ~60 000 massive (stellar mass M_star > 10^{11}
M_sun) galaxies out to z = 1 drawn from 55.2 deg2 of the United Kingdom
Infrared Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) and the Sloan
Digital Sky Survey (SDSS) II Supernova Survey. This is by far the largest
survey of massive galaxies with robust mass estimates, based on infrared
(K-band) photometry, reaching to the Universe at about half its present age. We
find that the most massive (M_star > 10^{11.5} M_sun) galaxies have experienced
rapid growth in number since z = 1, while the number densities of the less
massive systems show rather mild evolution. Such a hierarchical trend of
evolution is consistent with the predictions of the current semi-analytic
galaxy formation model based on Lambda CDM theory. While the majority of
massive galaxies are red-sequence populations, we find that a considerable
fraction of galaxies are blue star-forming galaxies. The blue fraction is
smaller in more massive systems and decreases toward the local Universe,
leaving the red, most massive galaxies at low redshifts, which would support
the idea of active 'bottom-up' formation of these populations during 0 < z < 1.Comment: Accepted for publication in MNRAS; replaced with revised version
(minor changes in results and wordings); MNRAS online early version availabl
Existence of Heavy Fermions in the Antiferromagnetic Phase of CeIn3
We report the pressure-dependent optical conductivity spectra of a heavy
fermion (HF) compound CeIn3 below the Neel temperature of 10 K to investigate
the existence of the HF state in the antiferromagnetic (AFM) phase. The peak
due to the interband transition in the hybridization gap between the conduction
band and nearly localized 4f states (c-f hybridization) appears at the photon
energy of about 20 meV not only in the HF regime but also in the AFM regime.
Both the energy and intensity of the c-f hybridization peak continuously
increase with the application of pressure from the AFM to the HF regime. This
result suggests that the c-f hybridization, as well as the heavy fermions,
exists even in the AFM phase of CeIn3.Comment: 5 pages, 3 figure
Pion Mass Effects in the Large Limit of \chiPT
We compute the large effective action of the non-linear
sigma model including the effect of the pion mass to order
. This action is more complex than the one corresponding
to the chiral limit not only because of the pion propagators but also because
chiral symmetry produce new interactions proportional to .
We renormalize the action by including the appropriate counter terms and find
the renormalization group equations for the corresponding couplings. Then we
estudy the unitarity propierties of the scattering amplitudes. Finally our
results are applied to the particular case of the linear sigma model and also
are used to fit the pion scattering phase shifts.Comment: FT/UCM/18/9
Cyborg Activism: Exploring the reconfigurations of democratic subjectivity in Anonymous
This article develops the concept of cyborg activism as novel configuration of democratic subjectivity in the Information Age by exploring the online collectivity Anonymous as a prototype. By fusing elements of human/machine and organic/digital the cyborg disrupts modern logics of binary thinking. Cyborg activism emerges as the reconfiguration of equality/hierarchy, reason/emotion, and nihilism/idealism. Anonymous demonstrates how through the use of contingent and ephemeral digital personae hierarchies in cyborg activism prove more volatile than in face-to-face settings. Emotions appear as an essential part of a politics of passion, which enables pursuing laughter and joy, expressing anger, and experiencing empowerment as part of a reasoned, strategic politics. Anonymous’ political content reconfigures nihilist sentiments, frustration, and political disenchantment on the one hand with idealist world views on the other. This enables the cohabitation and partial integration of a great diversity of political claims rooted in various ideologies
Evolution of cooperation driven by zealots
Recent experimental results with humans involved in social dilemma games
suggest that cooperation may be a contagious phenomenon and that the selection
pressure operating on evolutionary dynamics (i.e., mimicry) is relatively weak.
I propose an evolutionary dynamics model that links these experimental findings
and evolution of cooperation. By assuming a small fraction of (imperfect)
zealous cooperators, I show that a large fraction of cooperation emerges in
evolutionary dynamics of social dilemma games. Even if defection is more
lucrative than cooperation for most individuals, they often mimic cooperation
of fellows unless the selection pressure is very strong. Then, zealous
cooperators can transform the population to be even fully cooperative under
standard evolutionary dynamics.Comment: 5 figure
Analyticity, Crossing Symmetry and the Limits of Chiral Perturbation Theory
The chiral Lagrangian for Goldstone boson scattering is a power series
expansion in numbers of derivatives. Each successive term is suppressed by
powers of a scale, , which must be less than of order where is the Goldstone boson decay constant and is the
number of flavors. The chiral expansion therefore breaks down at or below . We argue that the breakdown of the chiral expansion is
associated with the appearance of physical states other than Goldstone bosons.
Because of crossing symmetry, some ``isospin'' channels will deviate from their
low energy behavior well before they approach the scale at which their low
energy amplitudes would violate unitarity. We argue that the estimates of
``oblique'' corrections from technicolor obtained by scaling from QCD are
untrustworthy.Comment: harvmac, 18 pages (3 figures), HUTP-92/A025, BUHEP-92-18, new version
fixes a TeX problem in little mod
Ovarian cancer symptom awareness and anticipated delayed presentation in a population sample
Background: While ovarian cancer is recognised as having identifiable early symptoms, understanding of the key determinants of symptom awareness and early presentation is limited. A population-based survey of ovarian cancer awareness and anticipated delayed presentation with symptoms was conducted as part of the International Cancer Benchmarking Partnership (ICBP). Methods: Women aged over 50 years were recruited using random probability sampling (n = 1043). Computer-assisted telephone interviews were used to administer measures including ovarian cancer symptom recognition, anticipated time to presentation with ovarian symptoms, health beliefs (perceived risk, perceived benefits/barriers to early presentation, confidence in symptom detection, ovarian cancer worry), and demographic variables. Logistic regression analysis was used to identify the contribution of independent variables to anticipated presentation (categorised as < 3 weeks or ≥ 3 weeks). Results: The most well-recognised symptoms of ovarian cancer were post-menopausal bleeding (87.4%), and persistent pelvic (79.0%) and abdominal (85.0%) pain. Symptoms associated with eating difficulties and changes in bladder/bowel habits were recognised by less than half the sample. Lower symptom awareness was significantly associated with older age (p ≤ 0.001), being single (p ≤ 0.001), lower education (p ≤ 0.01), and lack of personal experience of ovarian cancer (p ≤ 0.01). The odds of anticipating a delay in time to presentation of ≥ 3 weeks were significantly increased in women educated to degree level (OR = 2.64, 95% CI 1.61 – 4.33, p ≤ 0.001), women who reported more practical barriers (OR = 1.60, 95% CI 1.34 – 1.91, p ≤ 0.001) and more emotional barriers (OR = 1.21, 95% CI 1.06 – 1.40, p ≤ 0.01), and those less confident in symptom detection (OR = 0.56, 95% CI 0.42 – 0.73, p ≤ 0.001), but not in those who reported lower symptom awareness (OR = 0.99, 95% CI 0.91 – 1.07, p = 0.74). Conclusions: Many symptoms of ovarian cancer are not well-recognised by women in the general population. Evidence-based interventions are needed not only to improve public awareness but also to overcome the barriers to recognising and acting on ovarian symptoms, if delays in presentation are to be minimised
Silicon Mie Resonators for Highly Directional Light Emission from monolayer MoS2
Controlling light emission from quantum emitters has important applications
ranging from solid-state lighting and displays to nanoscale single-photon
sources. Optical antennas have emerged as promising tools to achieve such
control right at the location of the emitter, without the need for bulky,
external optics. Semiconductor nanoantennas are particularly practical for this
purpose because simple geometries, such as wires and spheres, support multiple,
degenerate optical resonances. Here, we start by modifying Mie scattering
theory developed for plane wave illumination to describe scattering of dipole
emission. We then use this theory and experiments to demonstrate several
pathways to achieve control over the directionality, polarization state, and
spectral emission that rely on a coherent coupling of an emitting dipole to
optical resonances of a Si nanowire. A forward-to-backward ratio of 20 was
demonstrated for the electric dipole emission at 680 nm from a monolayer MoS2
by optically coupling it to a Si nanowire
Structure of visible and dark matter components in spiral galaxies at redshifts z = 0.5-0.9
We have constructed self-consistent light and mass distribution models for
four disk galaxies at redshifts z = 0.48, 0.58, 0.81 and 0.88, using the HST
archive WFPC2 observations and rotation curves measured by Vogt et al. (1996)
and Rigopoulou et al. (2002). The models consist of three components: a bulge,
a disk and a dark matter halo. Similarly to the sample studied in Paper I (Tamm
& Tenjes, 2003), light distribution of the galaxies in the outer parts is
clearly steeper than a simple exponential disk. After applying k-corrections,
calculated mass-to-light ratios for galactic disks within the maximum disk
assumption are M/L_B = 0.9, 7.4, 4.3 and 1.4, respectively. Together with the
galaxies from Paper I, the mean = 2.5 at ~0.9, indicating no
significant evolution of M/L_B with redshift. Central densities of dark matter
halos for an isothermal model are 0.008, 0.035, 0.013, and 0.022 in units
M_sun/pc^3, respectively. Together with the galaxies from Paper I, the DM
central density of the four galaxies at mean readshift ~0.9 is rho(0) =
(0.012-0.028) M_sun/pc^3, also showing no significant evolution with redshift.Comment: 11 pages, 10 figures, Astron. Astrophys. accepte
Defining the challenges and opportunities for using patient-derived models in prostate cancer research
BackgroundThere are relatively few widely used models of prostate cancer compared to other common malignancies. This impedes translational prostate cancer research because the range of models does not reflect the diversity of disease seen in clinical practice. In response to this challenge, research laboratories around the world have been developing new patient-derived models of prostate cancer, including xenografts, organoids, and tumor explants.MethodsIn May 2023, we held a workshop at the Monash University Prato Campus for researchers with expertise in establishing and using a variety of patient-derived models of prostate cancer. This review summarizes our collective ideas on how patient-derived models are currently being used, the common challenges, and future opportunities for maximizing their usefulness in prostate cancer research.ResultsAn increasing number of patient-derived models for prostate cancer are being developed. Despite their individual limitations and varying success rates, these models are valuable resources for exploring new concepts in prostate cancer biology and for preclinical testing of potential treatments. Here we focus on the need for larger collections of models that represent the changing treatment landscape of prostate cancer, robust readouts for preclinical testing, improved in vitro culture conditions, and integration of the tumor microenvironment. Additional priorities include ensuring model reproducibility, standardization, and replication, and streamlining the exchange of models and data sets among research groups.ConclusionsThere are several opportunities to maximize the impact of patient-derived models on prostate cancer research. We must develop large, diverse and accessible cohorts of models and more sophisticated methods for emulating the intricacy of patient tumors. In this way, we can use the samples that are generously donated by patients to advance the outcomes of patients in the future
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