210 research outputs found
Pottery is king: bevel rim bowls and power in early urban societies of the ancient Near East
This thesis is about how material objects, specifically ceramics, are used to create and perpetuate political power of the ruling class. My research will demonstrate how bevel rim bowls were a form of structural violence in the Uruk/Protoliterate period Mesopotamia by forcing the people to create the very vessels they needed to obtain their rations. These vessels were widely used throughout the region, and as of yet their exact function is unknown. The Uruk period in Mesopotamia was a time of great change. Large urban centers were being formed and people were coming together in a new way to live in cities. A ceramic analysis of the bowls found in the region will help to determine their social and political importance
Expression of variant forms of the MUC1 gene correlates with the invasiveness of breast cancer cells
Enhancing the top signal at Tevatron using Neural Nets
We show that Neural Nets can be useful for top analysis at Tevatron. The main
features of and background events on a mixed sample are projected in
a single output, which controls the efficiency and purity of the
signal.Comment: 11 pages, 6 figures (not included and available from the authors),
Latex, UB-ECM-PF 94/1
On the relationship of first-episode psychosis to the amphetamine-sensitized state: a dopamine D2/3 receptor agonist radioligand study.
Schizophrenia is characterized by increased behavioral and neurochemical responses to dopamine-releasing drugs. This prompted the hypothesis of psychosis as a state of "endogenous" sensitization of the dopamine system although the exact basis of dopaminergic disturbances and the possible role of prefrontal cortical regulation have remained uncertain. To show that patients with first-episode psychosis release more dopamine upon amphetamine-stimulation than healthy volunteers, and to reveal for the first time that prospective sensitization induced by repeated amphetamine exposure increases dopamine-release in stimulant-naïve healthy volunteers to levels observed in patients, we collected data on amphetamine-induced dopamine release using the dopamine D2/3 receptor agonist radioligand [11C]-(+)-PHNO and positron emission tomography. Healthy volunteers (n = 28, 14 female) underwent a baseline and then a post-amphetamine scan before and after a mildly sensitizing regimen of repeated oral amphetamine. Unmedicated patients with first-episode psychosis (n = 21; 6 female) underwent a single pair of baseline and then post-amphetamine scans. Furthermore, T1 weighted magnetic resonance imaging of the prefrontal cortex was performed. Patients with first-episode psychosis showed larger release of dopamine compared to healthy volunteers. After sensitization of healthy volunteers their dopamine release was significantly amplified and no longer different from that seen in patients. Healthy volunteers showed a negative correlation between prefrontal cortical volume and dopamine release. There was no such relationship after sensitization or in patients. Our data in patients with untreated first-episode psychosis confirm the "endogenous sensitization" hypothesis and support the notion of impaired prefrontal control of the dopamine system in schizophrenia
CRYSTAL-CHEMISTRY AND INTRACRYSTALLINE RELATIONSHIPS OF ORTHO-PYROXENE IN A SUITE OF HIGH-PRESSURE ULTRAMAFIC NODULES FROM THE NEWER VOLCANICS OF VICTORIA, AUSTRALIA
A suite of orthopyroxenes from spinel lherzolite xenoliths associated with basanites occurring in the Victorian (Australia) post-Pliocene 'Newer Volcanics' province was investigated by means of a crystal chemical methodology which provides accurate site occupancy and site configuration parameters.
The M1 configuration is essentially constrained by Al(IV) rather than Fe2+. In addition, Fe3+, Cr3+ and Ti4+ are confined to M1 (Molin, 1989) and Al(IV) to TB. M2 is controlled by Fe(M2)2+ half arrow right over half arrow left constrained by (Fe2+ + Ca)M2 > 0.14 atoms per formula unit (p.fu.). Cation substitution in TB and M2 constrains the sum of the volumes of the respective polyhedra V(TB) + V(M2) to remain essentially constant. Therefore, M2 favours the retention of the large Fe2+ up to melting-point, causing nonideality of this iron-depleted orthopyroxene. As a consequence, the investigated orthopyroxene can be considered an ultimate Fe2+ carrier during partial mantle melting
Kinetics of Fe2+-Mg order-disorder in orthopyroxene: experimental studies and applications to cooling rates of rochs
We determined the forward rate constant (K+)
for the Fe2+\u2013Mg order\u2013disorder between the M2 and
M1 sites of orthopyroxene (OPx), which is described by
the homogeneous reaction Fe2+ (M2) + Mg(M1) M
Mg(M2) + Fe2+ (M1), by both ordering and disordering
experiments at isothermal condition and also by
continuous cooling experiments. The rate constant was
determined as a function of temperature in the range of
550\u2013750C, oxygen fugacity between quartz\u2013fayalite\u2013
iron and Ni\u2013NiO buffers, and at compositions of 16 and
50 mol% ferrosilite component. The K+ value derived
from disordering experiment was found to be larger than
that derived from ordering experiment at 550C, while at
T>580C, these two values are essentially the same. The
fO2 dependence of the rate constant can be described by
the relation K+ a (fO2)n with n=5.5\u20136.5, which is
compatible with the theoretically expected relation. The
Arrhenius relation at the WI buffer condition is given by
ln\uf0CoK\ufe
e \ubc
41511 12600XFe
T \uf0K
e
\ufe 28:26
\ufe 5:27 XFe; min1
where Co represents the total number of M2 + M1 sites
occupied by Fe2+ and Mg per unit volume of the crystal.
The above relation can be used to calculate the cooling
rates of natural OPx crystals around the closure temperature
(Tc) of Fe\u2013Mg ordering, which are usually below
300C for slowly cooled rocks. We determined the
Fe\u2013Mg ordering states of several OPx crystals ( Fs50)
from the Central Gneissic Complex (Khtada Lake),
British Columbia, which yields Tc 290C. Numerical
simulation of the change of Fe2+-Mg ordering in OPx as
a function of temperature using the above expression of
rate constant and a non-linear cooling model yields
quenched values of ordering states that are in agreement
with the observed values for cooling rates of 11\u201317C/
Myr below 300C. The inferred cooling rate is in
agreement with the available geochronological constraints
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