7,080 research outputs found
The role of women in the fur trade society of the Canadian west 1700-1850.
PhDThis thesis traces the evolution of the role played by
Indian, mixed-blood and white women in the development of
fur trade society in western Canada from about 1700 to 1850.
The importance of the role played by women in the fur trade
has been generally overlooked by historians of the subject
but such a study provides many insights into the complex
interaction which took place between European and Indian as
a result of this enterprise.
The men of both the Hudson's Bay and North West Companies
formed liaisons with women from the various tribes of western
Canada. In the English company, these unions were formed
in spite of official rulings to the contrary, whereas the
Canadian company actively encouraged unions between its
servants and Indian women. Such alliances served to cement
trade ties. Indian women performed a variety of important
economic tasks vital to the functioning of the fur trade
besides fulfilling the role of wife and mother left void by
the absence of white women.
Eventually, however, the Indian wife was to become a
source of friction rather than an effective liaison between
Indian and white, and by the early nineteenth century, her
place was being taken by a growing number of mixed-blood women.
The very child of the fur trade, the mixed-blood woman's dual
heritage gave her the ideal qualifications for a fur trader's
wife. It is significant that marriages contracted A la façon
du pays during this period showed a marked tendency to become
permanent unions.
After the union of the two companies in 1821, however,
the position of native women in fur trade society was
threatened by two outside forces--the missionaries and white
women. While the missionaries' attack on fur trade morality
was to lead to a good deal of cultural dislocation, the coming
of white women presented a potent threat to the prominence
of mixed-blood women in fur trade society. The resulting
development of social and racial tension between these two
groups of women was to erupt in a divisive scandal in Red
River in 1850, which symbolized the increasing ascendancy
of white women in western Canadian societ
Effects of Dust Scattering in Expanding Spherical Nebulae
The mean intensity of planetary nebulae with an expanding atmosphere is
modeled by considering dusty and dust-free atmospheres. The bulk matter density
is determined from the adopted velocity field through the equation of
continuity. The gas is assumed to consist of hydrogen and helium and the
gas-to-dust mass ratio is taken to be . The Rayleigh phase
function is employed for atomic scattering while the full Mie theory of
scattering is incorporated for determining the dust scattering and absorption
cross-section as well as the phase function for the angular distribution of
photons after scattering. It is shown that in a dust free atmosphere, the mean
intensity increases with the increase in the expansion velocity that makes the
medium diluted. The mean intensity profile changes significantly when dust
scattering is incorporated. The increase in forward scattering of photons by
the dust particles yields into an increase in the mean intensity as compared to
that without dust. The mean intensity increases as the particle size is
increased. Thus it is shown that both the expansion of the medium and the
presence of dust play important role in determining the mean intensity of a
planetary nebulae.Comment: 18 pages, Elseveir style (cls file included), 5 postscript figures,
Accepted for publication in New Astronom
Low-Volume Magmatism Linked to Flank Deformation on Isla Santa Cruz, Galápagos Archipelago, Using Cosmogenic \u3csup\u3e3\u3c/sup\u3eHe Exposure and \u3csup\u3e40\u3c/sup\u3eAr/\u3csup\u3e39\u3c/sup\u3eAr Dating of Fault Scarps and Lavas
Isla Santa Cruz is a volcanic island located in the central Galápagos Archipelago. The island’s northern and southern flanks are deformed by E–W-trending normal faults not observed on the younger Galápagos shields, and Santa Cruz lacks the large summit calderas that characterize those structures. To construct a chronology of volcanism and deformation on Santa Cruz, we employ 40Ar/39Ar geochronology of lavas and 3He exposure dating of fault scarps from across the island. The combination of Ar–Ar dating with in situ-produced cosmogenic exposure age data provides a powerful tool to evaluate fault chronologies. The 40Ar/39Ar ages indicate that the island has been volcanically active since at least 1.62 ± 0.030 Ma (2SD). Volcanism deposited lavas over the entire island until ~ 200 ka, when it became focused along an E–W-trending summit vent system; all dated lavas \u3c 200 ka were emplaced on the southern flank. Structural observations suggest that the island has experienced two major faulting episodes. Crosscutting relationships of lavas indicate that north flank faults formed after 1.16 ± 0.070 Ma, but likely before 416 ± 36 ka, whereas the faults on the southern flank of the island initiated between 201 ± 37 and 32.6 ± 4.6 ka, based on 3He exposure dating of fault surfaces. The data are consistent with a model wherein the northeastern faults are associated with regional extension owing to the young volcano’s location closer to the Galápagos Spreading Center at the time. The second phase of volcanism is contemporaneous with the formation of the southern faults. The expression of this younger, low-volume volcanic phase was likely related to the elongate island morphology established during earlier deformation. The complex feedback between tectonic and volcanic processes responsible for southward spreading along the southern flank likely generated persistent E-W-oriented magmatic intrusions. The formation of the Galápagos Transform Fault and sea-level fluctuations may be the primary causes of eruptive and deformational episodes on Santa Cruz
Recurrent pregnancy loss : diagnostic workup after two or three pregnancy losses? A systematic review of the literature and meta-analysis
BACKGROUND
Recurrent pregnancy loss (RPL) occurs in 1–3% of all couples trying to conceive. No consensus exists regarding when to perform testing for risk factors in couples with RPL. Some guidelines recommend testing if a patient has had two pregnancy losses whereas others advise to test after three losses.
OBJECTIVE AND RATIONALE
The aim of this systematic review was to evaluate the current evidence on the prevalence of abnormal test results for RPL amongst patients with two versus three or more pregnancy losses. We also aimed to contribute to the debate regarding whether the investigations for RPL should take place after two or three or more pregnancy losses.
SEARCH METHODS
Relevant studies were identified by a systematic search in OVID Medline and EMBASE from inception to March 2019. A search for RPL was combined with a broad search for terms indicative of number of pregnancy losses, screening/testing for pregnancy loss or the prevalence of known risk factors. Meta-analyses were performed in case of adequate clinical and statistical homogeneity. The quality of the studies was assessed using the Newcastle-Ottawa scale.
OUTCOMES
From a total of 1985 identified publications, 21 were included in this systematic review and 19 were suitable for meta-analyses. For uterine abnormalities (seven studies, odds ratio (OR) 1.00, 95% CI 0.79–1.27, I2 = 0%) and for antiphospholipid syndrome (three studies, OR 1.04, 95% CI 0.86–1.25, I2 = 0%) we found low quality evidence for a lack of a difference in prevalence of abnormal test results between couples with two versus three or more pregnancy losses. We found insufficient evidence of a difference in prevalence of abnormal test results between couples with two versus three or more pregnancy losses for chromosomal abnormalities (10 studies, OR 0.78, 95% CI 0.55–1.10), inherited thrombophilia (five studies) and thyroid disorders (two studies, OR 0.52, 95% CI: 0.06–4.56).
WIDER IMPLICATIONS
A difference in prevalence in uterine abnormalities and antiphospholipid syndrome is unlikely in women with two versus three pregnancy losses. We cannot exclude a difference in prevalence of chromosomal abnormalities, inherited thrombophilia and thyroid disorders following testing after two versus three pregnancy losses. The results of this systematic review may support investigations after two pregnancy losses in couples with RPL, but it should be stressed that additional studies of the prognostic value of test results used in the RPL population are urgently needed. An evidenced-based treatment is not currently available in the majority of cases when abnormal test results are present
Molecular line profiles as diagnostics of protostellar collapse: modelling the `blue asymmetry' in inside-out infall
The evolution of star-forming core analogues undergoing inside-out collapse
is studied with a multi-point chemodynamical model which self-consistently
computes the abundance distribution of chemical species in the core. For
several collapse periods the output chemistry of infall tracer species such as
HCO+, CS, and N2H+, is then coupled to an accelerated Lambda-iteration
radiative transfer code, which predicts the emerging molecular line profiles
using two different input gas/dust temperature distributions. We investigate
the sensitivity of the predicted spectral line profiles and line asymmetry
ratios to the core temperature distribution, the time-dependent model
chemistry, as well as to ad hoc abundance distributions. The line asymmetry is
found to be strongly dependent on the adopted chemical abundance distribution.
In general, models with a warm central region show higher values of blue
asymmetry in optically thick HCO+ and CS lines than models with a starless core
temperature profile. We find that in the formal context of Shu-type inside-out
infall, and in the absence of rotation or outflows, the relative blue asymmetry
of certain HCO+ and CS transitions is a function of time and, subject to the
foregoing caveats, can act as a collapse chronometer. The sensitivity of
simulated HCO+ line profiles to linear radial variations, subsonic or
supersonic, of the internal turbulence field is investigated in the separate
case of static cores.Comment: Accepted to MNRAS; 20 pages, 13 fig
Testing the blast wave model with Swift GRBs
The complex structure of the light curves of Swift GRBs has made the
identification of breaks, and the interpretation of the blast wave caused by
the burst, more difficult than in the pre-Swift era. We aim to identify breaks,
which are possibly hidden, and to constrain the blast wave parameters; electron
energy distribution, p, density profile of the circumburst medium, k, and the
continued energy injection index, q. We do so by comparing the observed
multi-wavelength light curves and X-ray spectra of our sample to the
predictions of the blast wave model.
We can successfully interpret all of the bursts in our sample of 10, except
two, within this framework and we can estimate, with confidence, the electron
energy distribution index for 6 of the sample. Furthermore we identify jet
breaks in a number of the bursts. A statistical analysis of the distribution of
p reveals that, even in the most conservative case of least scatter, the values
are not consistent with a single, universal value. The values of k suggest that
the circumburst density profiles are not drawn from only one of the constant
density or wind-like media populations.Comment: 14 pages, accepted by MNRAS after minor changes, including extension
of discussion (section 4.3
A projected Nesterov-Kaczmarz approach to stellar population-kinematic distribution reconstruction in Extragalactic Archaeology
In this paper, we consider the problem of reconstructing a galaxy's stellar
population-kinematic distribution function from optical integral field unit
measurements. These quantities are connected via a high-dimensional integral
equation. To solve this problem, we propose a projected Nesterov-Kaczmarz
reconstruction (PNKR) method, which efficiently leverages the problem structure
and incorporates physical prior information such as smoothness and
non-negativity constraints. To test the performance of our reconstruction
approach, we apply it to a dataset simulated from a known ground truth density,
and validate it by comparing our recoveries to those obtained by the widely
used pPXF software.Comment: 34 pages, 8 figure
Sliding mode control of quantum systems
This paper proposes a new robust control method for quantum systems with
uncertainties involving sliding mode control (SMC). Sliding mode control is a
widely used approach in classical control theory and industrial applications.
We show that SMC is also a useful method for robust control of quantum systems.
In this paper, we define two specific classes of sliding modes (i.e.,
eigenstates and state subspaces) and propose two novel methods combining
unitary control and periodic projective measurements for the design of quantum
sliding mode control systems. Two examples including a two-level system and a
three-level system are presented to demonstrate the proposed SMC method. One of
main features of the proposed method is that the designed control laws can
guarantee desired control performance in the presence of uncertainties in the
system Hamiltonian. This sliding mode control approach provides a useful
control theoretic tool for robust quantum information processing with
uncertainties.Comment: 18 pages, 4 figure
A 700 year record of Southern Hemisphere extratropical climate variability
Annually dated ice cores from West and East Antarctica provide proxies for past changes in atmospheric circulation over Antarctica and portions of the Southern Ocean, temperature in coastal West and East Antarctica, and the frequency of South Polar penetration of El Niño events. During the period AD 1700–1850, atmospheric circulation over the Antarctic and at least portions of the Southern Hemisphere underwent a mode switch departing from the out-of-phase alternation of multi-decadal long phases of EOF1 and EOF2 modes of the 850 hPa field over the Southern Hemisphere (as defined in the recent record by Thompson and Wallace, 2000; Thompson and Solomon, 2002) that characterizes the remainder of the 700 year long record. From AD 1700 to 1850, lower-tropospheric circulation was replaced by in-phase behavior of the Amundsen Sea Low component of EOF2 and the East Antarctic High component of EOF1. During the first phase of the mode switch, both West and East Antarctic temperatures declined, potentially in response to the increased extent of sea ice surrounding both regions. At the end of the mode switch, West Antarctic coastal temperatures rose and East Antarctic coastal temperatures fell, respectively, to their second highest and lowest of the record. Polar penetration of El Niño events increased during the mode switch. The onset of the AD 1700–1850 mode switch coincides with the extreme state of the Maunder Minimum in solar variability. Late 20th-century West Antarctic coastal temperatures are the highest in the record period, and East Antarctic coastal temperatures close to the lowest. Since AD 1700, extratropical regions of the Southern Hemisphere have experienced significant climate variability coincident with changes in both solar variability and greenhouse gase
Species by Environment Interactions Affect Pyrrolizidine Alkaloid Expression in Senecio jacobaea, Senecio aquaticus, and Their Hybrids
We examined the effects of water and nutrient availability on the expression of the defense pyrrolizidine alkaloids (PAs) in Senecio jacobaea and S. aquaticus. Senecio jacobaea, and S. aquaticus are adapted to different natural habitats, characterized by differing abiotic conditions and different selection pressures from natural enemies. We tested if PA concentration and diversity are plastic over a range of water and nutrient treatments, and also whether such plasticity is dependent on plant species. We also tested the hypothesis that hybridization may contribute to PA diversity within plants, by comparing PA expression in parental species to that in artificially generated F1 hybrids, and also in later generation natural hybrids between S. jacobaea and S. aquaticus. We showed that total PA concentration in roots and shoots is not dependent on species, but that species determines the pattern of PA diversification. Pyrrolizidine alkaloid diversity and concentration are both dependent on environmental factors. Hybrids produce a putatively novel PA, and this PA is conserved in natural hybrids, that are backcrossed to S. jacobaea. Natural hybrids that are backcrossed several times to S. jacobaea are with regard to PA diversity significantly different from S. jacobaea but not from S. aquaticus, while F1 hybrids are in all cases more similar to S. jacobaea. These results collectively suggest that PA diversity is under the influence of natural selection
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