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1.
《L'Anthropologie》2021,125(4):102928
The updated examination of the symbolic ocher drawing applied on a mammoth's skull which has been discovered at the Mezhyrich Paleolithic site, has led us to suggest its new interpretation – the drawing reflects an utterly stylized reproduction of a mammoth. The style of the drawing (acute angles) as well as the specific Mezhyrich décor (chevrons, rhombus) are probably based on the V-shaped lower jaw of mammoths which might have been associated with the “female's” triangle. The drawing of a mammoth has been implemented in the manner of “flattened untwisted reproduction” of its two profile projections – that is the method to create a 3-D image on a flat surface.  相似文献   

2.
A quick new method is described for the quantification of absolute nannofossil proportions in deep-sea sediments. This method (SMS) is the combination of Spiking a sample with Microbeads and Spraying it on a cover slide. It is suitable for scanning electron microscope (SEM) analyses and for light microscope (LM) analyses. Repeated preparation and counting of the same sample (30 times) revealed a standard deviation of ±10.5%. The application of tracer microbeads with different diameters and densities revealed no statistically significant differences between counts. The SMS-method yielded coccolith numbers that are statistically not significantly different from values obtained from the filtration-method. However, coccolith counts obtained by the random settling method are three times higher than the values obtained by the SMS- and the filtration-method.  相似文献   

3.
During the last decades, many techniques have been developed to reduce sample volume and improve cooling and warming rates during embryo vitrification. The vast majority are based on the “minimum drop size” concept, in which the vitrification solution around embryos is reduced by aspiration, leaving a tiny part of volume surrounding embryos. However, novel cryodevices were aimed to remove the entire vitrification solution. This study was designed to compare the “minimum drop size” technique using Cryotop® with the nylon mesh as cryodevice on rabbit morula embryos. The outcomes assessed were the in vitro development rates (experiment 1) and the offspring rates at birth (experiment 2). Embryos were vitrified in a two-step procedure; equilibrium (10% EG + 10% Me2SO) for 2 min and vitrification (20% EG + 20% Me2SO) for 1 min. In experiment 1, embryos (n = 323) were warmed and subsequently in vitro cultured for 48 h to assess the embryo developmental capability to reach the hatching-hatched blastocyst stage. In experiment 2, embryos were transferred using the laparoscopic technique (n = 369) to assess the offspring rate at birth. In this context, rates of in vitro embryo development were similar between vitrified groups (0.73 ± 0.042% and 0.66 ± 0.047% for Cryotop® and nylon mesh device, respectively), but lower than in the fresh group (0.97 ± 0.016%, p < 0.05). In experiment 2, there were no significant differences in survival rates (offspring born/total embryos transferred) among the Cryotop® device group and fresh group (0.41 ± 0.049% and 0.49 ± 0.050%, respectively). But significantly lower value was obtained in the nylon mesh device group (0.18 ± 0.030%). These results indicate that nylon mesh is not suitable as cryodevice for rabbit morula vitrification, remaining those using the “minimum drop size” methodology as the best option.  相似文献   

4.
The relative abundance of calcareous nannofossil taxa in a sequence of samples collected from a continuous Upper Maastrichtian section in Alabama has been analyzed using statistical techniques. Results indicate that an increase of arbitrarily chosen long-ranging forms can be represented by a slowly fluctuating secular trend with a superimposed cyclical component. Provided that a number of reasonable assumptions are made, the dominant frequencies of the periodic component are within the order of magnitude of the accepted frequency of the Perihelion cycle or “Milenkovitch astronomical insolation curves” (Milenkovitch, 1938).  相似文献   

5.
《Marine Micropaleontology》2002,45(2):175-190
The Upper Pliensbachian–Lower Toarcian Somma section (Central Italy), which displays alternation of limestone–marl lithotypes, was investigated for its calcareous nannofossil and CaCO3 contents. In order to evaluate the contribution of calcareous phytoplankton to the carbonate fraction of rocks a new method was applied combining a recently developed technique for nannofossil absolute quantification and measurements of nannofossil size. Our study suggests that nannofossils did not produce the bulk of carbonate mud in the studied section, although they contribute to different extents to the pelagic carbonate fraction. The contribution of both coccoliths and (mainly) the Incertae sedis Schizosphaerella to the carbonate fraction was important only in periods of reduced accumulation rates and/or during clay deposition. The highest estimated carbonate production by nannofossils in the studied section is around 83% of the total carbonate content, but in a sample containing only 12.8 wt% CaCO3. The observed limestone–marl alternations therefore result from cyclical export of carbonate mud from the shallow Latium–Abruzzi carbonate platform to the Umbria–Marche Basin and, only subordinately, from changes in nannoplankton productivity.  相似文献   

6.
《Comptes Rendus Palevol》2016,15(8):918-926
We describe a new species of mastodonsauroid temnospondyl from Algeria, Stanocephalosaurus amenasensis nov. sp., on the basis of two exquisite skulls from a Lagerstätte found in the lowermost formation of the Zarzaïtine Series, Illizi Basin, in the area of “La Reculée”, In Amenas region, Algeria. The new species is characterized by subtriangular nostrils with concave lateral borders; small orbits; postfrontals posteriorly very wide; very elongate parietals; smoothly concave posterior margin of the skull; ovoid anterior palatal vacuities; very posteriorly pointed choanae; oval interpterygoid fenestrae; and a short anterior extension of the cultriform process of the parasphenoid. S. amenasensis is different than the Algerian taxa previously erected by Lehman (1971)–“Parotosaurus lapparenti” and “Wellesaurus bussoni”–which we consider nomina dubia. It enlarges the distribution of the genus in northern Gondwana and supports the Early-Middle Triassic age of the lowermost formation of the Zarzaïtine Series. It also suggests that the local palaeoclimate was very seasonal and these aquatic amphibians died massively in a dewatering sebkha.  相似文献   

7.
Floral nectaries are closely associated with biotic pollination, and the nectar produced by corolla nectaries is generally enclosed in floral structures. Although some Swertia spp. (Gentianaceae), including S. bimaculata, evolved a peculiar form of corolla nectaries (known as “gland patches”) arranged in a conspicuous ring on the rotate corolla and that completely expose their nectar, little is known about the pollination of these plants. Two hypotheses were made concerning the possible effects of gland patches: visual attraction and visitor manipulation. The floral traits, mating system, and insect pollination of S. bimaculata were examined, and the pollination effects of gland patches were evaluated. A comparative study was made using Swertia kouitchensis, a species with fimbriate nectaries. Swertia bimaculata flowers were protandrous, with obvious stamen movement leading to herkogamy in the female phase and to a significant reduction in nectary–anther distance. The species is strongly entomophilous and facultatively xenogamous. The daily reward provided per flower decreased significantly after the male phase. The most effective pollinators were large dipterans, and the visiting proportion of Diptera was significantly higher in S. bimaculata than in S. kouitchensis. Most visitors performed “circling behavior” in S. bimaculata flowers. Removing or blocking the nectaries caused no reduction in visiting frequency but a significant reduction in visit duration, interrupting the circling behavior. The circling behavior was encouraged by nectar abundance and promoted pollen dispersal. Visitor species with small body size had little chance to contact the anthers or stigma, revealing a filtration effect exerted by the floral design. These results rejected the “visual attraction” hypothesis and supported the “visitor manipulation” hypothesis. The nectary whorl within a flower acted like a ring‐shaped track that urged nectar foragers to circle on the corolla, making pollination in S. bimaculata flowers more orderly and selective than that in classically generalist flowers.  相似文献   

8.
《L'Anthropologie》2022,126(1):102993
Analyzing lithic industries of Lower Pleistocene and beginning of Middle Pleistocene times allows to define three groups not clearly chronological but which reflect the cognitive evolution of prehistoric Men who knapped them and the constraints of the environment: - “Archaic Oldowan” industries in which raw flakes are dominant and no small tools retouched on flakes or debris are present; - “Classical Oldowan” industries in which raw flakes are dominant and small tools retouched on flakes and debris – especially scrapers – are present; - “Acheulean industries”, in which bifaces are present – generally in small proportions – and small retouched tools are increasingly standardized.  相似文献   

9.
Cone-beam breast Computed Tomography (bCT) is an X-ray imaging technique for breast cancer diagnosis, in principle capable of delivering a much more homogeneous dose spatial pattern to the breast volume than conventional mammography, at dose levels comparable to two-view mammography. We present an investigation of the three-dimensional dose distribution for a cone-beam CT system dedicated to breast imaging. We employed Monte Carlo simulations for estimating the dose deposited within a breast phantom having a hemiellipsoidal shape placed on a cylinder of 3.5 cm thickness that simulates the chest wall. This phantom represents a pendulant breast in a bCT exam with the average diameter at chest wall, assumed to correspond to a 5-cm-thick compressed breast in mammography. The phantom is irradiated in a circular orbit with an X-ray cone beam selected from four different techniques: 50, 60, 70, and 80 kVp from a tube with tungsten anode, 1.8 mm Al inherent filtration and additional filtration of 0.2 mm Cu. Using the Monte Carlo code GEANT4 we simulated a system similar to the experimental apparatus available in our lab. Simulations were performed at a constant free-in-air air kerma at the isocenter (1 μGy); the corresponding total number of photon histories per scan was 288 million at 80 kVp. We found that the more energetic beams provide a more uniform dose distribution than at low energy: the 50 kVp beam presents a frequency distribution of absorbed dose values with a coefficient of variation almost double than that for the 80 kVp beam. This is confirmed by the analysis of the relative dose profiles along the radial (i.e. parallel to the “chest wall”) and longitudinal (i.e. from “chest wall” to “nipple”) directions. Maximum radial deviations are on the order of 25% for the 80 kVp beam, whereas for the 50 kVp beam variations around 43% were observed, with the lowest dose values being found along the central longitudinal axis of the phantom.  相似文献   

10.
PurposeTo propose a “staggered overlap” technique in volumetric modulated arc therapy (VMAT) for craniospinal irradiation (CSI) and compare the dose distribution and plan robustness with “overlap” technique and “gradient optimization” approach.Methods and Materials6 patients previously treated in our clinic were retrospectively selected. 9 VMAT plans of each patient were optimized with “staggered overlap”, “overlap” and “gradient optimization” in overlapping region of 3 cm, 6 cm, and 9 cm separately. For the “staggered overlap” plan, adjacent field sets were intentionally overlapped by staggering field edges in an appropriate step size to avoid sharp dose gradient. Evaluation metrics including V95%, D2%, D98%, conformity number (CN) and homogeneity index (HI) were employed to evaluate the dose distribution. Moreover, shifts of the upper spinal field isocenter in each direction were performed to simulate junction errors for robustness analysis.ResultsThe CN and HI of VMAT plans with “staggered overlap” were 0.82 (0.811–0.822) and 0.113 (0.112–0.114), while they were 0.778 (0.776–0.782) and 0.131 (0.130–0.131) for plans with “gradient optimization”. In the robustness study, <3% dose deviations were found for 5 mm shifts in lateral and vertical directions with all techniques. In cranial-caudal direction, “overlap” technique created hot spots (D2% > 170%) and cold spots (D98% < 44%) in the junction region with 10 mm shifts. The dose deviations were decreased to 22% for plans with “staggered overlap” and 9 cm overlapping region.Conclusion“Staggered overlap” technique provides better plan quality as compared to “gradient optimization” approach and makes the plan more robust against junction errors as compared to “overlap” technique.  相似文献   

11.
Respiratory rate, an important antecedent of patient deterioration, is inadequately recorded by hospital staff, partially due to the absence of a reliable automated technique for measuring it. The ECG has been proposed by several authors in recent years as a source of reliable respiratory information. Most algorithms proposed use either respiratory sinus arrhythmia (RSA) or the R-peak amplitude (RPA) modulation of the ECG. In this paper, we propose a novel method for estimating respiratory rate from the ECG which fuses frequency information from the two methods. The method was evaluated on data from 40 young and elderly subjects and validated against a “gold standard” respiratory rate obtained from simultaneously recorded respiration data. The fusion method outperformed the RSA and RPA methods, giving a mean absolute error of 0.81 bpm for the young subject population and 0.84 bpm for the elderly, using 1-min windows of data. Unlike other algorithms, the technique does not underperform at the lower or higher respiratory rates.  相似文献   

12.
The protein complexes of the mitochondrial respiratory chain associate in defined ways forming supramolecular structures called respiratory supercomplexes or respirasomes. In plants, additional oxidoreductases participate in respiratory electron transport, e.g. the so-called “alternative NAD(P)H dehydrogenases” or an extra terminal oxidase called “alternative oxidase” (AOX). These additional enzymes were previously reported not to form part of respiratory supercomplexes. However, formation of respiratory supercomplexes might indirectly affect “alternative respiration” because electrons can be channeled within the supercomplexes which reduces access of the alternative enzymes towards their electron donating substrates. Here we report an investigation on the supramolecular organization of the respiratory chain in thermogenic Arum maculatum appendix mitochondria, which are known to have a highly active AOX for heat production. Investigations based on mild membrane solubilization by digitonin and protein separation by blue native PAGE revealed a very special organization of the respiratory chain in A. maculatum, which strikingly differs to the one described for the model plant Arabidopsis thaliana: (i) complex I is not present in monomeric form but exclusively forms part of a I + III2 supercomplex, (ii) the III2 + IV and I + III2 + IV supercomplexes are detectable but of low abundance, (iii) complex II has fewer subunits than in A. thaliana, and (iv) complex IV is mainly present as a monomer in a larger form termed “complex IVa”. Since thermogenic tissue of A. maculatum at the same time has high AOX and I + III2 supercomplex abundance and activity, negative regulation of the alternative oxidase by supercomplex formation seems not to occur. Functional implications are discussed.  相似文献   

13.
14.
Benthic foraminiferal composition assemblages and their temporal changes, ecological indices and foraminiferal densities are used to compare three coastal environments with different physicogeographical features in the Aegean Sea (coastal environment of Avdira–Vistonikos Gulf and Kitros–Thermaikos Gulf and open lagoonal environment of Vravron–South Evoikos Gulf). Three main foraminiferal assemblages have been recognized: a) “Assemblage A”; high degree of similarity between living and dead foraminiferal species, dominated by Ammonia beccarii, Elphidium spp. and relatively abundant and diverse miliolids, b) “Assemblage B1”; intermediate degree of similarity between live and dead assemblages, characterized by highly-abundant and well-diversified foraminiferal assemblages including the algal symbiont bearing Peneroplis pertusus together with Ammonia tepida and several small epiphytic rotaliids and miliolids, and c) “Assemblage B2”; absence of living individuals, strongly dominated by the opportunistic species A. tepida. Our results suggest a good comparison between living and dead assemblages from different coastal environments in the Aegean Sea, however the prevailing environmental conditions (vegetation cover, hydrodynamics, fresh water influx) have a strong impact on the taphonomic processes.  相似文献   

15.
The steroid hormone-receptor complex concentrations measured by “differential dissociation” techniques have to be corrected to obtain the true concentrations of receptor binding sites (Bs). For the calculation of Bs, the parameters kn (product of the equilibrium association constant and the concentration of binding sites of the “nonspecific” component) and f (fraction of the nonspecific binding measured in the experimental estimates of bound ligand by a given technique), previously proposed by Blondeau and Robel (J. P. Blondeau and P. Robel, 1975, Eur. J. Biochem.55, 375–384) are important. A new parameter of interest, ? [? = knf(kn + 1)], is discussed. The measurement of this parameter ? for three “differential dissociation” techniques allows the comparison of their efficiency and their reliability under various conditions for hormone receptor measurement in cytosol. Charcoal and hydroxylapatite methods are more efficient than the Sephadex G-25 filtration method. It is demonstrated that the “isotopic dilution” correction generally used for the estimation of the background of a given technique may be incorrect whatever the method of correction. A new method, the “double concentration measurement,” is developed. This method is simple, rapid, and precise. It requires two receptor binding measurements at two different saturating concentrations of ligand. This method allows the measurement of the estradiol receptor binding activity from calf uterine cytosol, with an error of less than 5% in samples containing the receptor either free or previously complexed with radioactive hormone, even in the presence of very high concentrations (≤0.5 μm) of radioactive steroid.  相似文献   

16.
It is unknown whether phenotypic plasticity in fitness‐related traits is associated with salinity–sodicity tolerance. This study compared growth and allocation phenotypic plasticity in two species with low salinity–sodicity tolerance (Chenopodium acuminatum and C. stenophyllum) and two species with high salinity–sodicity tolerance (Suaeda glauca and S. salsa) in a pot experiment in the Songnen grassland, China. While the species with low tolerance had higher growth and allocation plasticity than the highly tolerant species, the highly tolerant species only adjusted their growth traits and maintained higher fitness (e.g., plant height and total biomass) in response to increased soil salinity–sodicity, with low biomass allocation plasticity. Most plasticity is “apparent” plasticity (ontogenetic change), and only a few traits, for example, plant height:stem diameter ratio and root:shoot biomass ratio, represent “real” plasticity (real change in response to the environment). Our results show that phenotypic plasticity was negatively correlated with saline–sodic tolerance and could be used as an index of species sensitivity to soil salinity–sodicity.  相似文献   

17.
Accurate determination of age is essential for the comprehensive assessment and management of exploited shark populations. Enhancement of growth bands is necessary to accurately and efficiently determine age. However, most traditional techniques do not describe an efficiency of a series of procedures and the detailed protocol for different‐sized sharks. We describe a simple and highly successful technique for ageing vertebrae of blue shark (Prionace glauca) that we refer to as “burn method”, derived from the “break and burn method” and “shadowing method”—a simple procedure requiring an alkaline treatment to clean the vertebral centra and a burning treatment to enhance growth band visualization. We described optimal times for sharks of precaudal length of 50, 100, 150, and 200 cm as 44.9, 88.7, 134.0, 183.5 s of alkaline treatment, and 6.8, 8.9, 10.2, and 11.5 min of burning treatment; both longer and shorter exposure times resulted in higher failed sample frequencies. Using our burn method, it is possible to do ageing a sample from a wide angle, with the reader able to obtain information on growth bands from different perspectives. To critique different technique efficiencies, the index of average percent error (IAPE) and mean coefficient of variation (CV) are compared for independent readers using the burn method and other techniques (silver nitrate impregnation and the unstained shadowing methods). The precision of the burn method (IAPE, 4.1%; CV, 5.7%) was similar to that of silver nitrate impregnation (IAPE, 5.8%; CV, 8.2%) and unstained shadowing method (IAPE, 8.3%; CV, 11.8%). For younger specimens, the IAPE and CV of the burn method were lower than those of the other techniques, but, compared with other ageing methods, precision decreased for older sharks. We demonstrate that the burn method to be accurate for age determination of blue sharks, especially for specimens with less than 10 bands, but recommend simultaneous use of other methods, such as thin sectioning (the most common for structure‐based ageing) and bomb carbon dating, to accurately determine the age of older individuals.  相似文献   

18.
This paper presents the activity of the theme A “Modeling and simulation in biomedical research” within the GdR STIC Santé. This group has organized four scientific meetings and has managed one action, together with the theme B “Biomedical Signal and Image Processing”, during the period 2011–2012. The meetings have focused on modeling of the cardiorespiratory control, on the modeling and physiopathology of cardiovascular system and on Complex Systems in Biology and Medicine (co-organized with the GDR “Dynamique et Contrôle des Systèmes Complexes” – DYCOEC). The fourth one represents the official start of the “VPH-France” network that has been labeled by the Réseau National de Systèmes Complexes (RNSC). The SIGnal-processing and Modeling methods to Undertake Neonatal care during Development (SIGMUND) action has concerned seven hospitals and five CIC-IT (Clinical Technological Innovation Center) and has brought to the development of a regional project (Care-Premi) including three of the seven hospitals. The future works will focus: on strengthening the interactions with other topics of this GDR and with other GDRs, on application of modeling to solve real clinical heath problems, on the better acceptation of modeling by the industrial community.  相似文献   

19.
Organic residues are an important factor that directly affects fruiting tree seedlings' health at earlier stages. It provides a suitable environment for seedling growth by providing better nutrient ions, water, and aeration. However, low organic contents and high shrinkage of most organic materials mostly deteriorate ideal potting media characteristics. Low aeration, high water, and nutrients leaching decrease seedling growth and cause a significant loss of valuable resources. That is why the current study was conducted to screen out the best indigenous materials based on particle size to produce good characteristics bearing potting media. For that, eight different ingredients, i.e., “sugarcane”, “coconut coir”, “wheat straw”, “rice straw”, “corn cob”, “leaf litter”, “farmyard manure”, and “sunflower heads” were collected. Initially, all the materials were air-dried and processes as per requirement. After grinding, three particles size (fine = < 2 mm, medium = 3 mm and coarse = 5 mm) were separated by sieving. Results showed that decreasing particle size in “rice straw”, “corn cob”, “farmyard manure,” and “sunflower head” decreased leachate pH. Higher EC in leachates was negatively correlated with particle size in all potting media ingredients. Except for farmyard manure, fine particle size increases the water-holding ability of potting media ingredients. However, air-filled porosity was associated with a decrease in particle size of potting media in gradients. In conclusion, farmyard manure, “sunflower heads”, “leaf litter” and “sugarcane” should be incorporated while making a combination for potting media. More investigations are suggested by mixing different particle size ingredients to prepare potting media.  相似文献   

20.
The complete late Campanian–Maastrichtian succession of the South Atlantic reference DSDP Site 525A has been investigated to establish a detailed record of calcareous nannofossil biohorizons. A complete holostratigraphy of the core is presented for this interval and allows for global correlations to other Tethyan and Boreal reference sections for that interval. The new study allows for proposing a new time scale with a tie of Tethyan and Boreal nannofossil zonations. A new subzonation is proposed for the late Campanian UC16 Zone in the Tethyan Realm and the last occurrences of Uniplanarius trifidus and Zeugrhabdotus praesigmoides are demonstrated as markers of the Campanian–Maastrichtian boundary. The difference between cumulative first and last occurrences reflects the turnover dynamics of calcareous nanoplankton in the South Atlantic and highlights 6 major events. Five of them appear well related to major changes in sea-surface temperatures whereas the sixth event is likely the expression of a global decrease in primary productivity in the late Maastrichtian. Surprisingly, the turnover dynamics in calcareous nannoplankton appears completely unrelated to that observed in planktic foraminifera which shows only 4 major events with different timings. The two groups thus seem to have responded either very differently to similar environmental constraints or to different direct environmental constraints in the photic zone, although caused by the same global changes in climate.  相似文献   

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