Blackwater Draw Locality No.1, South Bank: Report For The Summer Of 1974 .

Abstract

Recent excavations at Blackwater Draw Locality No. 1 have resulted in clarification of theMiddle Plano horizon of the Carbonaceous Silts stratum. The 1974 field session at the South Bank of Locality No. 1 involved the excavation of a large amount of faunal material, includingthat of bison, turtle, bear, horse, and rodents. The range of artifacts found in association with Bison occidentalis remains at Locality No. 1 leads to a re-examination of the validity of the “Firstview complex.”     

The edge effect: A global problem. The trouble with culturing cells in 96-well plates

BackgroundThe use of 96-well plates is ubiquitous in preclinical studies. Corner and edge wells have been observed to be more prone to evaporation compared to interior wells.MethodsMammalian cells were cultured in 96-well plates over a period of 72 h. VWR and Greiner plates were tested. MTS reagent was added, and metabolic activity was determined after 2 h.ResultsWhen using VWR plates, cells showed a highly heterogeneous pattern of cell growth. The outer wells showed 35% lower metabolic activity than the central wells. Cells grown in rows two and three also grew sub-optimally (25% and 10% reduction compared to central wells). Greiner plates showed better homogeneity. Cells grown in the outer wells showed 16% lower metabolic activity while cells in rows two and three showed reductions of 7 and 1%, respectively. This edge effect was partially mitigated by storing the plates in loosely sealed wrapping during incubation. Placing a buffer between the wells of the plate further improved homogeneity for the Greiner plates.ConclusionDifferent brands of 96-well plates show different levels of the edge effect. Some clearly are inappropriate for such studies.General significanceEach laboratory needs to determine their own optimum conditions for culturing cells empirically before continuing to use multiwell plates. Otherwise, large artifacts may arise, affecting the quality of data, with the potential of introducing type I or type II errors.     

Phantom based qualitative and quantitative evaluation of artifacts in MR images of metallic hip prostheses

PurposeTo develop methods for qualitative and quantitative evaluation of MRI artifacts near metallic prostheses, and to compare the efficiency of different artifact suppression techniques with different types of hip prostheses.MethodsThree hip prostheses of cobalt-chromium, stainless steel, and titanium were embedded in agarose gel together with a rectilinear grid. Coronal MR images of the prostheses were acquired on a 1.5T scanner. Three pulse sequences were evaluated; TSE: a high-bandwidth turbo spin echo; VAT: TSE with view angle tilting, SEMAC: TSE with both VAT and slice distortion correction (6, 10 or 16 z-phase-encoding steps). Through-plane distortions were assessed as the length of visible gridlines, in-plane artifacts as the artifact area, and total artifacts by subtraction of an ideal, undistorted image from the actual image.ResultsVAT reduced in-plane artifacts by up to 50% compared to TSE, but did not reduce through-plane artifacts. SEMAC reduced through-plane artifacts by 60–80% compared to TSE and VAT. SEMAC in-plane artifacts were from 20% higher (6 encoding steps) to 50% lower (16 steps) than VAT. Total artifacts were reduced by 60–80% in the best sequence (SEMAC, 16 steps) compared to the worst (TSE). The titanium prosthesis produced 3–4 times lower artifact scores than the other prostheses.ConclusionsA rectilinear grid phantom is useful for qualitative and quantitative evaluation of artifacts provoked by different MRI protocols and prosthesis models. VAT and SEMAC were superior to TSE with high bandwidth. A proper number of z-encoding steps in SEMAC was critical. The titanium prosthesis caused least artifacts.     

a Reexamination of Spring Deposited Lithics from Blackwater Draw Locality N0.1

Abstract

Archaeological’ excavations at Blackwater Draw Locality No. 1 from 1962 to 1964 uncovered a number of spring conduits. Several of these contained very high concentrations of Paleo-Indian lithic materials, which exhibited a high polish on their surfaces. Investigations of this phenomenon (Haynes and Agogino 1966) have suggested thatthe distributions and concentration of lithics within spring conduits. are the result of intentional discard (possibly through ritual activity) by Paleo-Indians.     

‘Draw your pelvis’ test for assessing pelvic schema in people with Parkinsonʼs disease: a validity and reliability study

Aim: Body schema (i.e., the mental representation of the body and its parts) is important for cognitive and motor functions, with the pelvis constituting a core element in such schema. Although people with Parkinson?s disease exhibit misperceptions and deficits in body schema, there are currently no published tools available for assessing pelvic schema in this population. This study aimed to develop and establish feasibility, reliability, and validity of a novel drawing test ? ‘Draw Your Pelvis’ ? for assessing pelvic schema in people with Parkinson?s disease.

Materials and methods: Twenty people with idiopathic Parkinson?s disease (Hoehn &Yahr stages I–III; M age: 65.75?±?10.13) volunteered and were asked to manually draw a picture of their pelvis. Drawings were assessed and scored by 13 blinded raters over two sessions. Intra- and inter-rater reliability and content and criterion validity were investigated.

Results: The ‘Draw Your Pelvis’ test is shown to be feasible and quick to administer, with excellent inter-rater reliability for consistency (0.954–0.968) and absolute agreement (0.946–0.961). It also demonstrates good-excellent (0.614–0.950) intra-rater reliability, and is content valid.

Conclusions: The ‘Draw Your Pelvis’ test holds potential for clinicians and researchers in assessing pelvic schema and its deficits in people with Parkinson?s disease. In addition, this test could be used for investigating the effect of therapeutic interventions on body schema in this population. Future studies should explore this test in additional populations.     

Iterative image reconstruction using modified non-local means filtering for limited-angle computed tomography

PurposeLimited-angle CT imaging is an effective technique to reduce radiation. However, existing image reconstruction methods can effectively reduce streak artifacts but fail to suppress those artifacts around edges due to incomplete projection data. Thus, a modified NLM (mNLM) based reconstruction method is proposed.MethodsSince the artifacts around edges mainly exist in local position, it is possible to restore the true pixels in artifacts using pixels located in artifacts-free regions. In each iteration, mNLM is performed on image reconstructed by ART followed by positivity constraint. To solve the problem caused by ART-mNLM that there is undesirable information that may appear in the image, ART-TV is then utilized in the following iterative process after ART-mNLM iterates for a number of iterations. The proposed algorithm is named as ART-mNLM/TV.ResultsSimulation experiments are performed to validate the feasibility of algorithm. When the scanning range is [0, 150°], our algorithm outperforms the ART-NLM and ART-TV with more than 40% and 29% improvement in terms of SNR and with more than 58% and 49% reduction in terms of MAE. Consistently, reconstructed images from real projection data also demonstrate the effectiveness of presented algorithm.ConclusionThis paper uses mNLM which benefits from redundancy of information across the whole image, to recover the true value of pixels in artifacts region by utilizing pixels from artifact-free regions, and artifacts around the edges can be mitigated effectively. Experiments show that the proposed ART-mNLM/TV is able to achieve better performances compared to traditional methods.     

Three Human Skeletons From The Pk Burial Sheridan County,Wyoming

Abstract

Fragmentary skeletal material from a burial found near the Big Horn Mountains of north-central Wyoming was determined to constitute the remains of three individuals. The few artifacts in association provide little basis for an assessment of cultural affiliation, however, cranial characteristics suggest a close relationship to previously studied Siouan populations.

In February, 1962 Mr. Donald C. Grey of Sheridan, Wyoming submitted skeletal material recovered from the PK Burial Site in Sheridan County, Wyoming to Dr. William M. Bass for identification. Assistance in the analysis of the material was given by Mr. Donald C. Lacy, a graduate studentinphysicalanthropology. According to Mr. Grey (personal communication February 14, 1962), the PK Burial Site was discovered during the summer of 19 59 by a University of Illinois geology student, a member of a summer field crew based at Sheridan College, Sheridan, Wyoming. He discovered a human skull (See Fig. 1: a, b, and c) exposed in the side of a small hilltop overlooking a rodeo corral on a ranch west of Sheridan. The site is located in the foothills of the Big Horn Mountains.     

生物竞争排斥对油藏微生物群落结构变化影响

【目的】海上S油田采用生物竞争排斥技术治理油藏硫化氢产出取得一定成效,本研究通过揭示该技术对油藏环境中微生物群落结构的影响,尝试研究硫化氢治理过程中产生效果差异的因素。【方法】采用高通量测序分析等方法对加入硝酸盐、亚硝酸盐等药剂后,治理效果低效井、高效井及未治理井中不同微生物群落结构变化进行分析。【结果】与低效井和未治理井相比,高效井中的反硝化菌和石油降解菌种类和丰度明显增加,其中石油降解菌增加24.14%,反硝化细菌增加5.23%;Fe²⁺、Zn²⁺等离子的存在对不同井间治理效果差异和微生物群落变化具有一定影响。【结论】海上油田硫化氢治理中,生物竞争排斥技术不仅可以明显降低硫化氢产出,同时对油藏微生物群落环境也影响显著,微生物群落结构分析可作为硫化氢治理效果评价的重要指标,为海上油田硫化氢治理工作提供技术支持。     

The Use of Computer Programs for Mapping Archaeological Data

Abstract

Drawing table methods of mapping artifacts prohibit extensive experimentation with artifact distribution patterns. A digital computer may be used to map efficiently and economically. A program for plotting artifacts by geological levels is presented. Preparation of the data and use of the program is explained.     

Characterization of displacement forces and image artifacts in the presence of passive medical implants in low-field (<100 mT) permanent magnet-based MRI systems,and comparisons with clinical MRI systems

PurposeTo investigate the displacement forces and image artifacts associated with passive medical implants for recently-developed low-field (<100 mT) MRI systems, and to compare these with values from higher field strengths used for clinical diagnosis.MethodsSetups were constructed to measure displacement forces in a permanent magnet-based Halbach array used for in vivo MRI at 50 mT, and results compared with measurements at 7 T. Image artifacts were assessed using turbo (fast) spin echo imaging sequences for four different passive medical implants: a septal occluder, iliac stent, pedicle screw and (ferromagnetic) endoscopic clip. Comparisons were made with artifacts produced at 1.5, 3 and 7 T. Finally, specific absorption rate (SAR) simulations were performed to determine under what operating conditions the limits might be approached at low-field.ResultsDisplacement forces at 50 mT on all but the ferromagnetic implant were between 1 and 10 mN. Image artifacts at 50 mT were much less than at clinical field strengths for all passive devices, and with the exception of the ferromagnetic clip. SAR simulations show that very long echo train (>128) turbo spin echo sequences can be run with short inter-pulse times (5–10 ms) within SAR limits.ConclusionsThis work presents the first evaluation of the effects of passive implants at field strengths less than 100 mT in terms of displacement forces, image artifacts and SAR. The results support previous claims that such systems can be used safely and usefully in challenging enviroments such as the intensive care unit.     

The extent of representation,the relationships of artifacts and the anthropology of art

This paper provides an account of the potential roles that artifacts can occupy and distinguishes their occurrence as instruments of representation from other types of relationship of artifact use. When artifacts are employed as instruments of representation there is a deliberately constructed causal connection between the artifact and what it represents. This is in contrast to relationships of association in which the artifact takes on features of the context of its occurrence. Anthropological studies of artifact use in the native societies of Africa, America, the Indian Subcontinent and the Pacific are reviewed by comparing “dominant functions” that artifacts can serve.     

Impact of motion induced artifacts on automatic registration of lung tumors in Tomotherapy

PurposeTomotherapy MV-CT acquisitions of lung tumors lead to artifacts due to breathing-related motion. This could preclude the reliability of tumor based positioning. We investigate the effect of these artifacts on automatic registration and determine conditions under which correct positioning can be achieved.Materials and methodsMV-CT and 4D-CT scans of a dynamic thorax phantom were acquired with various motion amplitudes, directions, and periods. For each acquisition, the average kV-CT image was reconstructed from the 4D-CT data and rigidly registered with the corresponding MV-CT scan in a region of interest. Different kV–MV registration strategies have been assessed.ResultsAll tested registration methods led to acceptable registration errors (within 1.3 ± 1.2 mm) for motion periods of 3 and 6 s, regardless of the motion amplitude, direction, and phase difference. However, a motion period of 5 s, equal to half the Tomotherapy gantry period, induced asymmetric artifacts within MV-CT and significantly degraded the registration accuracy.ConclusionsAs long as the breathing period differs from 5 s, positioning based on averaged images of the tumor provides information about its daily baseline shift, and might therefore contribute to reducing margins, regardless of the registration method.     

Bayesian penalized-likelihood reconstruction algorithm suppresses edge artifacts in PET reconstruction based on point-spread-function

PurposeThe Bayesian penalized-likelihood reconstruction algorithm (BPL), Q.Clear, uses relative difference penalty as a regularization function to control image noise and the degree of edge-preservation in PET images. The present study aimed to determine the effects of suppression on edge artifacts due to point-spread-function (PSF) correction using a Q.Clear.MethodsSpheres of a cylindrical phantom contained a background of 5.3 kBq/mL of [¹⁸F]FDG and sphere-to-background ratios (SBR) of 16, 8, 4 and 2. The background also contained water and spheres containing 21.2 kBq/mL of [¹⁸F]FDG as non-background. All data were acquired using a Discovery PET/CT 710 and were reconstructed using three-dimensional ordered-subset expectation maximization with time-of-flight (TOF) and PSF correction (3D-OSEM), and Q.Clear with TOF (BPL). We investigated β-values of 200–800 using BPL. The PET images were analyzed using visual assessment and profile curves, edge variability and contrast recovery coefficients were measured.ResultsThe 38- and 27-mm spheres were surrounded by higher radioactivity concentration when reconstructed with 3D-OSEM as opposed to BPL, which suppressed edge artifacts. Images of 10-mm spheres had sharper overshoot at high SBR and non-background when reconstructed with BPL. Although contrast recovery coefficients of 10-mm spheres in BPL decreased as a function of increasing β, higher penalty parameter decreased the overshoot.ConclusionsBPL is a feasible method for the suppression of edge artifacts of PSF correction, although this depends on SBR and sphere size. Overshoot associated with BPL caused overestimation in small spheres at high SBR. Higher penalty parameter in BPL can suppress overshoot more effectively.     

Effect of number of views on cross-sectional Compton imaging: A fundamental study with backprojection

IntroductionWe have been developing a medical imaging technique using a Compton camera, which is expected to reconstruct three-dimensional images. If the number of views is not sufficient, star-shaped artifacts (streak artifacts) could arise in cross-sectional images. Therefore, we estimated the point spread function (PSF) of cross-sectional Compton images and the effect of the number of views by Monte Carlo simulations and experimental studies.Materials and methodsA cross-sectional Compton image was reconstructed using a dataset comprising 719 view directions and PSF was analyzed using a radial distribution. The peak height, full width at half maximum (FWHM), background (BG), and residual sum of squares (RSS) were calculated from the obtained PSF. In addition, RSSs were plotted against the number of views to estimate the required number to suppress star-shaped artifacts.ResultsThere was no correlation found between the number of views and both FWHM (16 mm) and peak/BG ratio (∼1 × 10⁴). RSSs were reduced with the number of views and approached the minimum asymptotically. Correlation was observed between the required number of views and the number of Compton events used for image reconstruction.ConclusionWe determined the PSF of cross-sectional Compton images and the effect of the number of views on the images. The required number of views to suppress the star-shaped artifact is related to the square root of the number of Compton events used to reconstruct the image. From this study, we concluded that 21 or more views are required for clinical purposes.     

On the Ewald Artifacts in Computer Simulations. The Test-Case of the Octaalanine Peptide With Charged Termini

Abstract

The treatment of electrostatic interactions in molecular simulations is of fundamental importance. Ewald and related methods are being increasingly used to the detriment of cutoff schemes, which are known to produce several artifacts. A potential drawback of the Ewald method is the spatial periodicity that is imposed to the system, which could produce artifacts when applied in the simulation of liquids. In this work we analyze the octaalanine peptide with charged termini in explicit solvent, for which severe effects due to the use of Ewald sums were predicted using continuum electrostatics. Molecular Dynamics simulations for a total of 158 nanoseconds were performed in cells of different sizes. From the comparison of the results of different system sizes, no significant periodicity-induced artifacts were observed. It is argued that in current biomolecular simulations, the incomplete sampling is likely to affect the results to a larger extent than the artifacts induced by the use of Ewald sums.     

Scapula Skin-Dressing And Fiber-Processing Tools

Abstract

Information from ethnographic and archaeological literature supports the interpretation that some bison scapula tools were used for dressing skins. Sim!lar scapula artifacts may have been used for processing bark fiber used in making cordage or weaving. References to possible scapula processing tools from the Plains Northwest Coast, Great Lakes Riverine Area, and the Southeast are summarized. Specimens made of deer and elk scapulae probably represent functionally similar tool types. These artifacts may be more common than the available reports on Plains sites indicate, and archaeologists should exercise care when identifying scapula tools. We cannot assume that all scapula artifacts represent hoes or hoe fragments.     

A Human Skeleton From The Pryor Creek Burial, 24YL404, Yellowstone County,Montana

Abstract

An adult human skeleton, found associated with artifacts of both Indian and White manufacture near Billings, Yellowstone County, Montana, is thought on the basis of cranial measurements and morphological features to be a prehistoric Crow Indian.     

Two Nebraska Culture Storage Pits from Doniphan County,Kansas

Abstract

The materials from two Nebraska culture storage pits located in Doniphan County, Kansas are described. Comparisons made with the pottery and stone artifacts from previously-described Nebraska culture sites show a considerable resemblance.     

The Effects of Frost Heaving on Objects in Soils,II: Laboratory Experiments

Abstract

Recent laboratory studies of frost heaving of artifacts in soils are relevant to archaeologists, geomorphologists, and Arctic and Alpine specialists. Investigations were undertaken to determine the susceptibility to frost heave of artifacts with differing effective heights (the vertical dimension of buried objects). To this end, wooden dowels oriented from 0 to 90 degrees from the horizontal and vertically oriented wooden parallelepipeds of different lengths were emplaced in saturated soil and alternately frozen and thawed. These studies show that differential frost heaving occurred; objects with larger angles from the horizontal and vertically oriented objects with greater lengths experience greater upward movement due to frost heaving. Moreover, in addition to being frost heaved upwards, artifacts oriented at differing angles tend to rotate towards the vertical with each freeze-thaw cycle.

The significance of the results is twofold. First, statistical models generated from the data provide a quantitative assessment of the role of effective height in frost heaving of artifacts. Secondly, the results are important in modeling the mechanics of the frost heaving process because the distribution of component forces may be inferred.