1,799 research outputs found
Basic and applied biology of the primate reproductive tract – a symposium in honor of the career of Dr Robert M Brenner: Introduction and overview
A critical period of progesterone withdrawal precedes menstruation in macaques
Macaques are menstruating nonhuman primates that provide important animal models for studies of hormonal regulation in the uterus. In women and macaques the decline of progesterone (P) at the end of the cycle triggers endometrial expression of a variety of matrix metalloproteinase (MMP) enzymes that participate in tissue breakdown and menstrual sloughing. To determine the minimal duration of P withdrawal required to induce menses, we assessed the effects of adding P back at various time points after P withdrawal on both frank bleeding patterns and endometrial MMP expression. Artificial menstrual cycles were induced by treating the animals sequentially with implants releasing estradiol (E(2)) and progesterone (P). To assess bleeding patterns, P implants were removed at the end of a cycle and then added back at 12, 24, 30, 36, 40, 48, 60, or 72 hours (h) after the initial P withdrawal. Observational analysis of frank bleeding patterns showed that P replacement at 12 and 24 h blocked menses, replacement at 36 h reduced menses but replacement after 36 h failed to block menses. These data indicate that in macaques, a critical period of P withdrawal exists and lasts approximately 36 h. In other similarly cycled animals, we withdrew P and then added P back either during (12–24 h) or after (48 h) the critical period, removed the uterus 24 h after P add back and evaluated endometrial MMP expression. Immunocytochemistry showed that replacement of P during the critical period suppressed MMP-1, -2 and -3 expression along with menses, but replacement of P at 48 h, which failed to suppress mense, suppressed MMP-1 and MMP-3 but did not block MMP-2. We concluded that upregulation of MMPs is essential to menses induction, but that after the critical period, menses will occur even if some MMPs are experimentally blocked
Unusual: The Death Penalty for Inadvertent Killing
Can a burglar who frightens the occupant of a house, causing a fatal heart attack, be executed? More generally, does the Eighth Amendment permit capital punishment of one who causes death inadvertently? This scenario is possible in the significant minority of American jurisdictions that permit capital punishment for felony murder without requiring a mental state of intent to kill or reckless indifference to human life. Thus far, Eighth Amendment death penalty jurisprudence has required a culpable mental state of recklessness for execution of accomplices in a fatal felony, but has not yet addressed the culpability required for execution of the actual killer. In this Article, we urge the recognition of a new Eighth Amendment norm against executing even actual killers who lack a culpable mental state of at least recklessness, with respect to the victim’s death. Using the methods employed by the Supreme Court for determining “evolving standards of decency,” we survey the pertinent homicide and sentencing laws of the fifty-three criminal law jurisdictions in the United States. Second, we evaluate the facts of the cases that resulted in the nearly five hundred executions that have taken place since 1973, when the post-Furman statutes became operative, and 2016, in those jurisdictions permitting execution for inadvertent killing. We did the same for the facts of the 1755 cases of all death row inmates convicted in those jurisdictions and alive at the time of the study (2016). This analysis shows that capital punishment for inadvertent killing has become “truly unusual,” and therefore, unconstitutional.
Optimal and fast rotational alignment of volumes with missing data in Fourier space
AbstractElectron tomography of intact cells has the potential to reveal the entire cellular content at a resolution corresponding to individual macromolecular complexes. Characterization of macromolecular complexes in tomograms is nevertheless an extremely challenging task due to the high level of noise, and due to the limited tilt angle that results in missing data in Fourier space. By identifying particles of the same type and averaging their 3D volumes, it is possible to obtain a structure at a more useful resolution for biological interpretation. Currently, classification and averaging of sub-tomograms is limited by the speed of computational methods that optimize alignment between two sub-tomographic volumes. The alignment optimization is hampered by the fact that the missing data in Fourier space has to be taken into account during the rotational search. A similar problem appears in single particle electron microscopy where the random conical tilt procedure may require averaging of volumes with a missing cone in Fourier space. We present a fast implementation of a method guaranteed to find an optimal rotational alignment that maximizes the constrained cross-correlation function (cCCF) computed over the actual overlap of data in Fourier space
Dynamics of glomerular ultrafiltration: VI. Studies in the primate
Dynamics of glomerular ultrafiltration: VI. Studies in the primate. Pressures and flows were measured in accessible surface glomeruli of the squirrel monkey under conditions of normal hydropenia. Mean glomerular capillary hydrostatic pressure and the mean glomerular transcapillary hydrostatic pressure difference (ΔP) averaged approximately 45 mm Hg and 35 mm Hg, respectively. These findings are in close accord with recent direct estimates in the rat. The net driving force for ultrafiltration was found to decline from a maximum value of about 12 mm Hg at the afferent end of the glomerular capillary network essentially to zero by the efferent end, indicating that, in the monkey as in the rat, filtration pressure equilibrium is achieved under normal hydropenic conditions. The monkey differs from the rat in one important respect, however, in that, as has long been recognized, the monkey tends to have higher systemic total plasma protein concentrations (CA) than the rat. This is of interest since monkey, like man, is found to have lower filtration fractions than the rat. Since ΔP is found to be essentially similar in monkey and rat, and since, at filtration pressure equilibrium, filtration fraction is determined by ΔP and CA, these observed differences in filtration fraction between rodent and primate must therefore be due to these differences in CA
New Insights on the Sequence Stratigraphic Architecture of the Dakota Formation in Kansas–Nebraska–Iowa from a Decade of Sponsored Research Activity
The Cretaceous Dakota Formation in the areas of Kansas, Nebraska, and Iowa contains a rich and well-preserved microflora of fossil palynomorphs. A comprehensive listing of these taxa is presented in this publication as part of a continuing effort to develop a refined biostratigraphic scheme for mid-Cretaceous terrestrial deposits in North America. The Dakota Formation in this region contains four distinctive Albian-Cenomanian palynostratigraphic zones that are used to partition the unit into successive depositional cycles, and each zone records deposition in fluvial-estuarine environments. The late Albian Kiowa-Skull Creek depositional cycle at the base of the Dakota Formation is recognized throughout the study area, and is also recognized in other parts of the Cretaceous North American Western Interior basin. The overlying newly recognized latest Albian "Muddy-Mowry Cycle" is formally defined for the first time in this paper and correlates with depositional cycles recognized by other workers in other parts of the Western Interior basin. The Cenomanian lower Greenhorn Cycle is already widely recognized by many other workers throughout the Western Interior basin. Laterally extensive thin zones of pervasive carbonate mineral cementation are noted in fluvial-estuarine deposits in the Dakota Formation. They are believed to have formed as synsedimentary cements that precipitated below estuarine marine-flooding surfaces in settings related to discharging paleoground waters. The existence of these early diagenetic cementation zones has important implications for the recognition of diagenetic barriers and baffles to modern fluid flow in the Dakota Formation. New stable isotopic data on these authigenic cements are reported in this paper and add to a body of published data on the δ18O of mid-Cretaceous paleoprecipitation in North America
Технологическая подготовка производства детали типа «Звездочка» на станках с ЧПУ
Целью выпускной квалификационной работы является совершенствование технологического процесса изготовления детали типа "Звездочка". В выпускной квалификационной работе рассмотрены четыре раздела: технологический, конструкторский, финансовый менеджмент и социальная ответственность. В технологическом разделе приведен проектный вариант технологического процесса изготовления детали и приведены необходимые расчеты. В конструкторском разделе представлено сконструированное станочное приспособление для фрезерного станка с ЧПУ. В разделе финансового менеджмента определена себестоимость проектирование технологического процесса.The goal of the final qualifying work is the improvement of the technological process of manufacturing the "Zvezdochka" type parts. In the final qualifying work, four sections were considered: technological, design, financial management and social responsibility. In the technological section, the design version of the technological process for manufacturing the part is given and the necessary calculations are given. In the design section, the machine tool for the CNC milling machine is presented. In the section of financial management, the cost of designing the process is determined
The collateral network concept: Remodeling of the arterial collateral network after experimental segmental artery sacrifice
ObjectiveA comprehensive strategy to prevent paraplegia after open surgical or endovascular repair of thoracoabdominal aortic aneurysms requires a thorough understanding of the response of the collateral network to extensive segmental artery sacrifice.MethodsTen Yorkshire pigs underwent perfusion with a low-viscosity acrylic resin. With the use of cardiopulmonary bypass, 2 animals each were perfused in the native state and immediately, 6 hours, 24 hours, and 5 days after sacrifice of all segmental arteries (T4–L5). After digestion of surrounding tissue, the vascular cast of the collateral network underwent analysis of arterial and arteriolar diameters and the density and spatial orientation of the vasculature using light and scanning electron microscopy.ResultsWithin 24 hours, the diameter of the anterior spinal artery had increased significantly, and within 5 days the anterior spinal artery and the epidural arterial network had enlarged in diameter by 80% to 100% (P < .0001). By 5 days, the density of the intramuscular paraspinous vessels had increased (P < .0001), a shift of size distribution from small to larger arterioles was seen (P = .0002), and a significant realignment of arterioles parallel to the spinal cord had occurred (P = .0005).ConclusionsWithin 5 days after segmental artery occlusion, profound anatomic alterations in the intraspinal and paraspinous arteries and arterioles occurred, providing the anatomic substrate for preservation of spinal cord blood flow via collateral pathways
- …