Surface Stone Research Articles

Clinical study on complication of minimally invasive lithotripsy of urinary system calculus

Objective To investigate the complications of minimally invasive lithotripsy in urinary system calculi. Methods The clinical data of 136 patients with urinary calculi who were treated in our hospital from December 2014 to December 2016 were analyzed by retrospective analysis. All patients were treated with minimally invasive lithotomy. Postoperative complications and the influencing factors, and postoperative risk factors were analyzed by logistic regression. Results Of the 136 patients, 51 cases of postoperative complications, accounting for 37.5%, of which 42 (30.9%)cases of fever, 3 cases of infection(2.2%), 3(2.2%) cases of stones, 1 case of delayed bleeding (0.7%), 1 case of renal pelvis perforation (0.7%), 2 cases of peripheral organ injury (1.5%), the highest proportion of fever complications were found, and postoperative fever complications were univariate analysis. There was significant correlation between the factors such as age, diabetes mellitus, operation time, urinary culture and urinary white blood cells (P<0.05), and had no significant correlation with the factors such as gender, hydronephrosis and hypertension logistic regression analysis showed that stone surface area, stone shape and operation time, intraoperative blood loss and other factors were independent risk factors for postoperative fever of urinary tract stones (P<0.05). Conclusions The incidence of fever, infection, residual stones and other complications is easy to occur after minimally invasive lithotripsy. The surface area, shape and operation time of calculus are the independent risk factors of postoperative fever. Complications of risk factors for effective control, enhance the prognosis of patients. Key words: Urinary Calculi; Surgical Procedures, Minimally Invasive; Postoperative Complications

Stone Sculpture Wear: Alteration/Fragmentation Processes and Their Impact on Carving Traces of Tenon Heads of Chavín de Huántar, Peru

ABSTRACTThe study of the stone sculpture production process is subject to the preservation and visibility of tool traces and surface finishes. In this article it is proposed that the parameters developed in conservation for the diagnosis of surface stone alteration processes can be used as descriptors to isolate the attributes of postproduction conditions and their influence on variation in the appearance of stonework traces. It shows how the application to a case study served to determine the alterations that contribute to the deterioration of carving traces, the selection of the best-preserved areas for recording, and the retrieval of information for increasing the sample number. The results of fracturing patterns caused by a stress sector in the sculpture body are shown. Certain sets of alterations occurred together, either affecting the integrity of the carving groove or increasing the texturing finish of the polished surface.

A photoacoustic pulse-echo probe for monitoring surface stone mechanical properties: Validation tests in consolidation of Carrara marble

The present work focuses on the development and validation of a laser-based photoacoustic sensor for non-destructive monitoring of surface stone mechanical properties. The sensor is constituted of a carbon black target excited by fiber-coupled Q-Switched Nd:YAG(1064 nm) laser with variable pulse duration between 10 and 50 ns, a superimposed PVDF film transducer, and gel coupler. The high optical absorption of the target and its relatively large lateral size allowed generating planar longitudinal pressure transients of amplitude around 1 MPa using a laser pulse fluence of about 8 mJ/cm2. The probe provided an almost flat spectral response over a bandwidth of 7.5–30 MHz. Thanks to the high pulse-to-pulse laser emission stability, the pressure transients were highly reproducible in amplitude and waveform. These features and the FFT analysis of the back reflected signal were exploited to characterize the surface mechanical properties of decayed Carrara marble upon consolidation. Treatment tests were carried out using three commercial products: acrylic-siloxane polymer, a fluoroelastomer-acrylic polymer, and ethyl-silicate. The acoustic reflection and then surface sound speed spectra were measured and analyzed for the first time within a spectral window of 1–30 MHz. Surface speed spectra and dephasing derived from reflectance measurements resulted to be essential parameters for characterizing and monitoring stone consolidation. The results achieved provide evidence that the technique proposed offers significant advantages with respect to traditional approaches and can represent an effective tool in conservation-restoration of stone artifacts, wall paintings, and other.

The deterioration of Apuan white marble in contemporary architectural context

Assessment of the state of conservation of the marble slabs of the Oslo Opera House and investigation of the causes of their discoloration;.• Ongoing phenomenon of calcite grains detachment, with inter- and intra-granular corrosion, due to the atmospheric conditions to which the marble slabs are exposed;.• Presence of siloxanes and oxidized by-products of a mixture of treatments identified by micro-FTIR spectroscopy;.• No migration phenomena from the cementitious bedding mortars used for cladding towards the surface. © 2018 Elsevier Masson SAS The conservation of contemporary buildings is particularly challenging as only few information about their degradation and guidelines for their maintenance are available and at the same time, despite their architectural importance, the attention and caring procedures are nοt adequate to safeguard standards. The Oslo Opera House is a high-standing contemporary architecture (opening 2008) characterized by a large ornamental pavement mainly made of Apuan marble slabs. After a few years, large parts of the marble surface suffered from a marked yellow discoloration and dirt accumulation. In this context, the current research was carried out aiming at assessing the state of conservation of the marble slabs and investigating the causes of their discoloration, to suggest possible remediation and adequate maintenance procedures. Due to the extreme microclimatic conditions, a severe inter- and intra-granular decohesion of the calcite grains can be observed by microscopic analyses, while a surface corrosion phenomenon of the crystals is in progress. The chemical analyses of surface stone material from the slabs allow the detection of deteriorated organic by-products, as a result of the degradation of previous protective treatments, excluding the correlation of iron ions concentration with the discoloration. The state of conservation gathered so far was the starting point for the development of a tailor-made cleaning methodology of the marble cladding and a complete revision of the protective treatments and ordinary maintenance protocol.

Modelling soil solute release and transport in run‐off on a loessial slope with and without surface stones

AbstractStone covers on loessial slopes can increase the time of infiltration by slowing the velocity of the overland flow, which reduces the transport of solutes, but few mechanistic models have been tested under water‐scouring conditions. We carried out field experiments to test a previously proposed, physically based model of water and solute transport. The area of soil infiltration was calculated from the uncovered surface area, and Richards' equation and the kinematic wave equation were used to describe water infiltration and flow along slopes with stone covers. The transport of chemicals into the run‐off from the surface soil, presumably by diffusion, and their movement in the soil profile could be described by the convection–diffusion equations of the model. The simulated and measured data correlated well. The stones on the soil surface reduced the area available for infiltration but increased the Manning coefficient, eventually leading to increased water infiltration and decreased solute loss with run‐off. Our results indicated that the traditional model of water movement and solute migration could be used to simulate water transport and solute migration for stone‐covered soil on loessial slopes.

Spectroscopic characterization of historical building materials: The case study of the Biblioteca Nazionale Marciana (Venice, Italy)

AbstractThe building designed by Sansovino in 1532 as the new Mint of Venice underwent a change in its intended use, becoming in 1900 the Biblioteca Nazionale Marciana. A spectroscopic study concerning the surface stone materials of the current reading room (previously a courtyard) was attempted since the transformation lead to heavy micro‐ and macroclimatic variations.Many alterations were observed, such as blackening, cracking, incrustations, and mortars powdering. The employed techniques, such as Raman and Fourier Transform InfraRed‐Attenuated Total Reflectance spectroscopy, allowed identifying the substrate main components and their alteration phases, mainly sulfates and nitrates.These data represent important information when approaching such a famous building because every further intervention must be based on accurate scientific results.

Vegetation – environment relationships of the Hamersley Ranges, a mountainous desert of north-west Australia

Understanding environment-vegetation relationships provides important ecological insights, and here we examined such relationships for the Hamersley Ranges of North West Australia. We were particularly interested to see if such relationships were similar to those of other mountainous deserts. We used direct gradient analyses of floristic and environmental variables (constrained ordination), supplemented by identification of environmental differences between plant communities, assessment of environment-vegetation associations and partitioning of the floristic variance between environmental, climatic and spatial variables. Most communities could be differentiated from others according to environmental variables, with slope, surface stone cover, topsoil phosphorus and pH particularly good at differentiating between plant communities. There was strong association between communities and classes of landform and/or geological substrate. Gradient analysis demonstrated the primary floristic gradient was linked to a complex of several topographic, edaphic and geomorphic variables. This was interpreted as floristic change along broad topo-sequences from mountain/ridge tops to valley floors over which gradients in key environmental variables occur. Gradient analyses of other mountainous deserts have reported similar findings. A key distinction in the complex gradient identified for the Hamersley Ranges is the inclusion of topsoil phosphorus (rather than nitrogen) and time since last fire. The second most important floristic gradient was linked to soil pH and conductivity, which reflects floristic variation due to differences in geological substrate throughout the study area.

A Review ofXiongnu Tombs in Mongolia

본 논문에서는 2(X)(년 이후 집중적인 조사가 이루어진 봉콜지역 흉노시대 분묘에 대한조사 현황을살펴보고 흉노무덩의구조와편년을비롯한분묘관련연구성과를검토하였다. 봉콜 전역에서는 대략 기원전 1세기 전 중반부터 기원후 1세기에 해당하는 적석목곽이 기본 구조인흉노무덩이 발견된다 각무덩군간의거리가상당하지만，봉골전역의흉노무덩은지상에노출된 외부 형태와 지하의 매장주체부 구조가 거의 유사하다 대형 흉노무덩의 경우 칠마차 칠목관과 급은제 목관 장식， 비 단을 비 롯한 각종 직물， 급은제 장신구， 동복과 각종 청동 용기， 동경， 급은제 pj- 규 장식을 비롯한여러 벌의 마구류， 각종 생활용기(대형 용， 호， 동잔， 성발) 풍 부장유울에서 거의 통일한 구성을 보여주고 있으며 소형 흉노 무덩 역시 대형 무덩에 비해 소략하기는 하기만 각종 장신구 마구 토기(심발 호) 동 일관된 부장 양상이 확인된다 봉골 전역에 걸쳐 흉노시대 분묘의 구조와부장품의 구성이 동일하다는 점은 당시 무덩의 조성에 중앙의 강력한통제가있었음을시사한다 흉노 무덩은 외부 적석 구조에 따라 원형(고리형)과 방형으로 나면다 원형은 묘도가 없는데 비해， 방형은 일부 유적을 제외한 대부분의 무덩에서 묘도를 갖추고 있다 초대형을 제외한 대부분의 흉노무덩에서는 별도의 봉분을 확인할 수 없는 반면， 대형 또는초대형 무덩은 ‘뀐자형의 테두리를 띠라석축벽이부가되어약간의 봉분구조를갖추고있다 매장주체부는목관이나목곽의사용。1 일반적인데 2중목곽은 대형의 ‘뀐’자형 평연 구조를 갖춘 흉노 무덩에서 주로 확인된다 특히 배장묘 를 갖춘 2중목곽의 초대형 무덩은 규모 부장품의 동급과수량 변에서도 다른무덩과는 뚜렷한 써를보이고있는 바 최고계층의묘제로사용되었을것으로추정된다This paper reviews the recent archaeological investigation on Xiongnu tombs in Mongolia that took place since 2000, and examines the research on the structure and chronology ofXiongno tombs. In the 21th century, manyXiongnu tombs, dated from 1st century BCE to 1st century CE, were discovered and excavated in Mongolia. Despite the considerable distance between the burial groups, the Xiongnu tombs throughout Mongolia are similar in the appearance on the ground and the internal structures. In case oflarge Xiongnu tombs, coff&igrave;n walls were covered with felt rug or silk, and decorated with gold or silver ornaments. Inside or outside the coff&igrave;n, ritual grave goods of similar composition are found that include animal bones, pottery, ornaments, horse equipment, bronze mirrors, lacquer wares, bronze cooking pots, jade decorations and various weapons. The small Xiongnu tombs are also relativε， ly simple compared to large tombs, but various grave goods such as jewelry, harnesses, and earthenware can be found. The fact that the tomb structure and the composition of grave goods are the same throughout Mongolia indicates a strong central control of the tomb composition during the Xiongnu era Most Xiongnu tombs have two types of surface stone structure: square and roughly circular. The circ ar tombs do not have dromos, whereas the square tombs mostly have a long rectangular dromos or entry chamber on the south side. In most of the Xiongnu tombs the mound cannot be identif&igrave;ed, but large or extra-large tombs have a mound structure with a stone wall along the outline. Inside the large tomb there is usually a single or a double (exterior and interior) wooden chamber holding the coff&igrave;n at the bottom of a burial pit. In particular, extra-large tombs with -shaped outline, which have many satellite burials near the main tomb, are remarkably different in size of structure and quantity of grave goods from the others. Such tombs are thought to have belonged t。e aristocratic cl잉s of the Xiongnu.

Detecting Terrain Stoniness From Airborne Laser Scanning Data †

Three methods to estimate the presence of ground surface stones from publicly available Airborne Laser Scanning (ALS) point clouds are presented. The first method approximates the local curvature by local linear multi-scale fitting, and the second method uses Discrete-Differential Gaussian curvature based on the ground surface triangulation. The third baseline method applies Laplace filtering to Digital Elevation Model (DEM) in a 2 m regular grid data. All methods produce an approximate Gaussian curvature distribution which is then vectorized and classified by logistic regression. Two training data sets consisted of 88 and 674 polygons of mass-flow deposits, respectively. The locality of the polygon samples is a sparse canopy boreal forest, where the density of ALS ground returns is sufficiently high to reveal information about terrain micro-topography. The surface stoniness of each polygon sample was categorized for supervised learning by expert observation on the site. The leave-pair-out (L2O) cross-validation of the local linear fit method results in the area under curve A U C = 0 . 74 and A U C = 0 . 85 on two data sets, respectively. This performance can be expected to suit real world applications such as detecting coarse-grained sediments for infrastructure construction. A wall-to-wall predictor based on the study was demonstrated.

Complementary approaches to the identification of bison processing for storage at the Kutoyis complex, Montana

Identifying sources of variability in carcass processing activities is central to the construction of inferences about primary consumption as well as production of storable and transportable by-products. In the northwestern Plains of North America, bison harvesting and processing underwent important changes in scale and intensity in the millennium before European contact. Recent studies of surface stone architecture dating to this time period point to band- and supra-band investment in the planning and construction of elaborate hunting facilities. Site-scale butchering and carcass processing, on the other hand, are good indicators of the degree to which hunting families foresaw the need to secure foodstuffs for future consumption and trade. This report discusses the results of a magnetic survey, excavations, and faunal analysis undertaken at the Kutoyis Site (24GL366), a Late Prehistoric-period hunting complex located in Montana, to characterize processing activities associated with large-scale communal bison hunting. Positive magnetic readings across the site's floodplain, discovery of processing features, and patterned bone fragmentation across the site suggest an investment in the production of storable and transportable by-products such as pemmican, and support architectural and environmental evidence of economic intensification.

Evaluation of RUSLE and PESERA models for predicting soil erosion losses in the first year after wildfire in NW Spain

The accelerated erosion that occurs after wildfire in forest ecosystems is a major factor affecting the sustainability of these environments. Soil erosion prediction models are crucial for estimating fire impacts and for planning post-fire soil stabilization measures. We evaluated the performance of the Revised Universal Soil Loss Equation (RUSLE) and the Pan-European Soil Erosion Risk Assessment (PESERA) models by comparing the soil losses predicted by the models and the soil losses measured in the first year after wildfires in NW Spain. Two alternative RUSLE approaches were also considered: i) the use of reduction coefficients for R and C factors and ii) the application of a soil erodibility reduction factor to take into account soil surface stone cover. The RUSLE model overestimated the observed erosion rates in all cases. The PESERA model performed reasonably well in predicting soil losses, but needs a better characterization of soil burn severity in the soil inputs (crusting and erodibility) because of the high sensitivity of the model to these parameters.In both cases, there is an urgent need for an appropriate assessment of the impact on soil burn severity in the erosional process. This seems critical if these models are to be used for post-fire soil stabilization activities planning.

Laboratory frost sorting by needle ice: a pilot experiment on the effects of stone size and extent of surface stone cover

AbstractSorted patterned ground is ubiquitous where gravelly fine soil experiences freeze–thaw cycles, but experimental studies have rarely been successful in reproducing such patterns. This article reports an attempt to reproduce miniature sorted patterns by repeating needle‐ice formation, which simulates frost sorting in regions dominated by diurnal freeze–thaw cycles. Six full‐scale laboratory models were tested. They consisted of near‐saturated volcanic fine soil topped by small stones of uniform size; the models explored a range of stone size (~6, ~12, ~17 and ~22 mm) and surface abundance (20, 40 and 60% cover). The stones were placed in a grid on the surface. These models were subjected to 20–30 temperature excursions between 10 °C and −5 °C in 12 hours. The evolution of surface patterns were visually traced by photogrammetry. A data logging system continuously monitored vertical soil displacements, soil temperatures and moistures at different depths. All experimental runs displayed needle‐ice formation (2–3 cm in height) and resulting displacement of stones. The soil domains tended to heave faster and higher than the stones, leading to outward movement of the former and concentration of the stones. In plan view, smaller stones showed relatively fast and long‐lasting movements, while larger stones stabilized after the first five cycles. The 20% stone cover produced stone islands, whereas the 40% cover resulted in sorted labyrinths (a circle‐island complex) that may represent incipient sorted circles. The average diameter or spacing of these forms are 12–13 cm, being comparable to those in the field. The experiments imply that needle‐ice activity promotes rapid formation of sorted patterns, although the formation of well‐defined sorted circles may require hundreds of diurnal frost heave cycles. Copyright © 2014 John Wiley &amp; Sons, Ltd.

26Al/10Be dating of an aeolian dust mantle soil in western New South Wales, Australia

Aeolian dust mantle soils are an important element of many landscapes in south-eastern Australia, though the age of these aeolian deposits has not been radiometrically determined. At Fowlers Gap in western New South Wales, surface cobbles of silcrete and quartz overlie a stone-free, aeolian dust mantle soil, which has a thickness of about 1.6m. The clay-rich aeolian dust deposit in turn lies upon a buried silcrete and quartz stone layer. Modelling in-situ cosmogenic 26Al and 10Be concentrations measured in both the surface quartz stones and in the buried quartz layer of rocks, reveals that each has experienced a complex exposure-burial history. Due to the absence of quartz stones or sand at intermediate depths, our cosmogenic 26Al and 10Be modelling was not able to determine a definitive mechanism of stone pavement formation and stone burial. Various scenarios of stone formation, transport, burial and exhumation were tested that constrain the age of the deposit to range from 0.9±0.2Ma to 1.8±0.2Ma, based largely on different assumptions taken for the time-dependency of the net sedimentation rate. This corresponds with the initiation of the Simpson Desert dune fields and the deflation of lakes in central Australia, which probably responded to the shift to longer-wavelength, larger-amplitude Quaternary glacial cycles at around 1Ma. Sensitivity analyses were carried out to identify those parameters which better constrained model outputs. Within model errors, which largely are the result of analytical errors in measured 26Al and 10Be concentrations, all three competing theories of colluvial wash, upward displacement of stones, and cumulic pedogenesis are possible mechanisms for the formation of the surface stone pavement.

Observations of surface stone movement on the Goreibitsu Pass in Fukushima Prefectur

Observations of surface stone movement on the Goreibitsu Pass in Fukushima Prefectur

Soil erodibility in Europe: A high-resolution dataset based on LUCAS

The greatest obstacle to soil erosion modelling at larger spatial scales is the lack of data on soil characteristics. One key parameter for modelling soil erosion is the soil erodibility, expressed as the K-factor in the widely used soil erosion model, the Universal Soil Loss Equation (USLE) and its revised version (RUSLE). The K-factor, which expresses the susceptibility of a soil to erode, is related to soil properties such as organic matter content, soil texture, soil structure and permeability. With the Land Use/Cover Area frame Survey (LUCAS) soil survey in 2009 a pan-European soil dataset is available for the first time, consisting of around 20,000 points across 25 Member States of the European Union. The aim of this study is the generation of a harmonised high-resolution soil erodibility map (with a grid cell size of 500m) for the 25 EU Member States. Soil erodibility was calculated for the LUCAS survey points using the nomograph of Wischmeier and Smith (1978). A Cubist regression model was applied to correlate spatial data such as latitude, longitude, remotely sensed and terrain features in order to develop a high-resolution soil erodibility map. The mean K-factor for Europe was estimated at 0.032thahha−1MJ−1mm−1 with a standard deviation of 0.009thahha−1MJ−1mm−1. The yielded soil erodibility dataset compared well with the published local and regional soil erodibility data. However, the incorporation of the protective effect of surface stone cover, which is usually not considered for the soil erodibility calculations, resulted in an average 15% decrease of the K-factor. The exclusion of this effect in K-factor calculations is likely to result in an overestimation of soil erosion, particularly for the Mediterranean countries, where highest percentages of surface stone cover were observed.

Landscape Engineering and Organizational Complexity among Late Prehistoric Bison Hunters of the Northwestern Plains

Studies of hunter-gatherer sociopolitical organization consistently exclude terrestrial big-game hunters—pedestrian bison hunters, in particular—from discussions of emerging complexity. To an important extent, this exclusion stems both from the ethology of bison and its consequences for mobile hunters and from the character of their archaeological record, which lacks conventional indicators of organizational complexity such as high-status burials and long-term storage facilities. However, this record exhibits stone architecture of monumental proportions. We argue that evidence of emerging sociopolitical complexity is embodied in the hunters’ ability to (1) invest extensively on landscape engineering to amass communal bison wealth for consumption, storage, and exchange, and (2) produce and reproduce ritual wealth among individuals and restricted sectors of the group. Through a multiscalar research design that integrates thousands of surface stone features with data recovered from kill site excavation, ethn...

Evaluation of soil conservation measures on a highly erodible soil in the Free State province, South Africa

Soil erosion is a problem in South Africa, and is exacerbated by poor land use practices and erodible soils. Several methods are available to address the problem and a runoff trial was conducted over four rainfall seasons on an erodible, duplex soil. Various geotextiles and physical measures were evaluated. The treatments comprised jute matting, a synthetic geotextile, woven palm mats, micro-basins, surface stone rows and bare soil as the control. Runoff was recorded by a datalogger, with sediment load manually sampled after each rainfall event. All the treatments performed better than the bare soil, but there were several variations. Runoff was on average 38–63% less than that produced by the bare soil, whereas sediment load was on average 16–72% less. Re-establishment of vegetation cover was up to twice that of the bare plot. Approximation of soil loss showed reduction from an annual rate of over 50 t ha−1 to between 1 and 7 t ha−1 for most treatments. While many land users or communities may not be able to obtain or afford relatively expensive geotextiles, more basic treatments, requiring a lower level of inputs, are available as a cost-effective means of addressing the problem of excessive soil loss.

Comparative study of pulsed laser cleaning applied to weathered marble surfaces

The removal of unwanted matter from surface stones is a demanding task in the conservation of cultural heritage. This paper investigates the effectiveness of near-infrared (IR) and ultraviolet (UV) laser pulses for the cleaning of surface deposits, iron oxide stains and different types of graffiti (black, red and green sprays and markers, and black cutting-edge ink) on dolomitic white marble. The performance of the laser techniques is compared to common cleaning methods on the same samples, namely pressurized water and chemical treatments. The degree of cleaning achieved with each technique is assessed by means of colorimetric measurements and X-ray microfluorescence. Eventual morphological changes induced on the marble substrate are monitored with optical and electronic microscopy. It is found that UV pulsed laser ablation at 266nm manages to clean all the stains except the cutting-edge ink, although some degree of surface erosion is produced. The IR laser pulses at 1064nm can remove surface deposits and black spray acceptably, but a yellowing is observed on the stone surface after treatment. An economic evaluation shows that pulsed laser cleaning techniques are advantageous for the rapid cleaning of small or inaccessible surface areas, although their extensive application becomes expensive due to the long operating times required.

The Italian National Guidelines for the fire safety of facades

Traditionally, the facades' design buildings where once only focused on architectural or aesthetic purposes (in addition, of course, of whether protective issues). Nowadays, thanks to the technological development of the construction works and the use of new types of materials, the facades' design should also address fire safety related aspects.In Europe and especially in Italy – where the types of building facades are built with windows of small surface and natural stone coverings – the green building/sustainability movement has resulted in the development of new concepts in facade or curtain wall design that intended to enhance the energy efficiency of building facades. These new building surfaces are covered by extensive panelling fitted with insulating materials or by wide glass surfaces, capable of carry out the most diverse purposes including, just to name a few: energy reduction, climate comfort, recovery of electricity through photovoltaic panels that convert sunlight into electricity, large space for advertising purpose.One of the main fire safety goal for a building design is to restrict the vertical fire spread so that the smoke and flames are limited to the fire origin floor. The new building facade and curtain wall topologies could overwhelms concerns for fire safety, therefore the Italian National fire service has released a Fire Code Guideline in order to address the fire safety design for an high rise building facade. This paper aims to show the guideline contents and the related fire safety facades concerns.

表面礫移動の連続観測装置の試作と福島県御霊櫃峠における観測

表面礫移動の連続観測装置の試作と福島県御霊櫃峠における観測