Strontium isotopes measurement from bunker cave system: a contribution for the multi-proxy paleoclimate research of Central Europe

In recent years speleothem has been intensely studied due to its great potential of registering paleoclimate proxies but some considerably uncertaintiesregarding speleothem proxy interpretation still exist. In order to minimize these uncertainties, multi-proxy approach has been used. Here is presented the strontium isotope record from Bunker cave, northwest Germany. This cave was previously studied and has proved well record paleoclimate changes during Holocene for central Europe.87Sr/86Sr ratio is presented for rain water, A-horizon soil (water and leachate), C-horizon soil (water and leachate), host rock and host rock leachate, drip water and from a stalagmite (Bu4) previously dated covering the Holocene. Upper soil presented the higher values in contrast with host rock (lower values). Drip water and C-horizon presented intermediated ratios. Sr isotopesare used to track the source of 87Sr/86Sr in the Bunker system, resulting in a mixture between A-horizon soil, C-horizon soil and host rock. A decreasing trend in Bu4 indicates change in the Sr source in the system

Vibrational spectroscopy of natural cave mineral monetite CaHPO4 and the synthetic analog

Monetite is a phosphate mineral formed by the reaction of the chemicals in bat guano with calcite substrates and is commonly found in caves. The analog of the mineral monetite CaHPO4 has been synthesized and the Raman and infrared spectra of the natural monetite originating from the Murra-el-elevyn Cave, Eucla, Western Australia, compared. Monetite is characterized by a complex set of phosphate bands that arise because of two sets of pairs of phosphate units in the unit cell. Raman and infrared bands are assigned to HPO4(2-), OH stretching and bending vibrations. Infrared bands at 1346 and 1402 cm−1 are assigned to POH deformation modes. Vibrational spectroscopy confirms the presence of monetite in the cave system.

Changes in the storage and sink of carbon dioxide in subsurface atmospheres controlled by climate-driven processes: the case of the Ojo Guareña karst system

A comprehensive environmental monitoring program was conducted in the Ojo Guareña cave system (Spain), one of the longest cave systems in Europe, to assess the magnitude of the spatiotemporal changes in carbon dioxide gas (CO2) in the cave–soil–atmosphere profile. The key climate-driven processes involved in gas exchange, primarily gas diffusion and cave ventilation due to advective forces, were characterized. The spatial distributions of both processes were described through measurements of CO2 and its carbon isotopic signal (δ13C[CO2]) from exterior, soil and cave air samples analyzed by cavity ring-down spectroscopy (CRDS). The trigger mechanisms of air advection (temperature or air density differences or barometric imbalances) were controlled by continuous logging systems. Radon monitoring was also used to characterize the changing airflow that results in a predictable seasonal or daily pattern of CO2 concentrations and its carbon isotopic signal. Large daily oscillations of CO2 levels, ranging from 680 to 1900 ppm day−1 on average, were registered during the daily oscillations of the exterior air temperature around the cave air temperature. These daily variations in CO2 concentration were unobservable once the outside air temperature was continuously below the cave temperature and a prevailing advective-renewal of cave air was established, such that the daily-averaged concentrations of CO2 reached minimum values close to atmospheric background. The daily pulses of CO2 and other tracer gases such as radon (222Rn) were smoothed in the inner cave locations, where fluctuation of both gases was primarily correlated with medium-term changes in air pressure. A pooled analysis of these data provided evidence that atmospheric air that is inhaled into dynamically ventilated caves can then return to the lower troposphere as CO2-rich cave air.

喀斯特洞穴系统中稳定同位素地球化学特征及其环境意义

洞穴次生化学沉积物作为探索区域性、全球性气候变化规律和环境变迁史最重要的“信息库”之一，取得了不少有价值的研究成果。但同时，随着高分辨、短时间尺度气候-环境变化记录研究的开展与数据的进一步积累，也发现此类研究目前存在着一些问题与局限性。事实上，洞穴次生化学沉积物环境替代指标的形成经历了一系列复杂的过程，包含的影响因数相对较多。总的来说，其形成过程从大气降雨开始，穿越土壤层、洞穴盖板层到洞穴内滴水中CO2逸出、过饱和的CaCO3结晶和水中携带的不溶物沉淀。其中在不同的气候与环境条件下水与各层（如土壤层、表层喀斯特和潜水带等）中媒介之间发生的物理化学过程决定了环境替代指标的真实涵义。但目前有关这些替代指标的形成过程及其影响因子、适用性等方面的研究工作相当薄弱，尽管包括本文作者所在课题组在内的一些学者已认识到这一工作的重要性，零星做了一点工作，但还无法形成系统的认识。 在我国西南部，缺少类似我国北方的巨厚黄土堆积，但岩溶发育，且连片分布，其面积居世界首位（东亚喀斯特片区的中心）。因此，在该地区气候环境变迁史研究中，环境记录“档案”——洞穴次生化学沉积物在该方面所起的作用具有与北方黄土一样的重要意义。该研究为利用洞穴次生化学沉积物的地球化学特征恢复古生态环境意义的研究奠定坚实的理论基础。基于此，我们选择我国西南喀斯特发育最为典型的贵州作为研究区域，通过对分布于境内不同地方100多个洞穴进行实地考察和综合评判之后，筛选出一个系列的4个喀斯特洞穴作为研究对象，分别选取一定数量采样点进行采样。在前人研究的基础上，更加深入系统地对该4个洞穴系统中的稳定同位素（碳和氧同位素）进行研究。 分别系统地采集了4个洞穴系统中的大气、植物、土壤、土壤空气、土壤水、基岩、泉水、洞穴滴水、洞穴空气、塘水、潭水和滴水对应的洞穴次生化学沉积物等，现场测试pH值、电导率（Cond.）和气温（T）等，室内分别测试了稳定同位素和其他相关指标（如各种离子浓度等），以期开展不同生态环境条件下正在形成的洞穴次生化学沉积物及其对应的洞穴滴水的地球化学特征的比较研究，揭示它们对气候环境变化的响应机制，即稳定同位素等洞穴次生化学沉积物环境替代指标的现代形成过程以及各种影响因子。 本研究主要取得以下几点认识： 1. 虽然缺乏同气候、等海拔和生物量在10~90 t/hm2之间的植被序列洞穴的对比，以及对土壤有机质和土壤微生物活性等的相关试验研究，但根据分析仍可获知，洞穴化学次生沉积物的碳同位素的生物量效应是由植物碳同位素及土壤CO2微生物分馏作用机制共同制约。也就是说，洞穴沉积物碳同位素信号所反映的信息包括植被碳同位素组成及其生物量所控制的土壤性质（如微生物等），并不一定指示地表植被的C3/C4比例变化，甚至也不一定指示乔、灌、草的比例，当然也不仅仅是植被覆盖变化的简单体现。总之，生物量效应在横向上是存在的，它至少部分控制着洞穴化学次生沉积物碳同位素的变化，在对石笋等碳同位素的高分辨率解译过程中是不容忽视的。其机理可能是，生物量的大小控制土壤性质（营养和含水量等），进而激发或抑制土壤微生物群落的生长和发育，从而影响土壤有机质的分解过程最终导致次生沉积物δ13C值的变化。 2. 贵州喀斯特地区δ13CSOC与源植物的δ13C差值最大达8‰以上，其主要受土壤水热条件、质地和pH值控制。由此可见，δ13CSOC动态总体上反映了植被破坏历史。不过由于未进行具体年限测定，植被受破坏的具体时间未知。因此，今后除了需对SOC含量等问题进行系统的研究外，14C定年以及喀斯特地区更多土壤剖面等的工作也有待进一步开展。 3. 洞穴水在下渗过程中普遍发生了混合作用，致使从上（地表）到下（洞穴）δ13CDIC值变化幅度变小。除了QXD和JJD中δ13CDIC值偏重的滴水外，基岩对滴水碳同位素组成的影响都相对较小，而各洞穴中滴水（沉积物）等碳同位素组成与洞穴上覆植被等有关，是生态环境的真实记录。LFD中各种洞穴水δ13CDIC值之间基本上都达到或接近同位素平衡，且与洞穴系统的生态环境有很好的相关关系（非常显著的时间变化）；QXD和JJD之间的洞穴水（除土壤水外）δ13CDIC动态极为相似，即同一洞穴同期不同滴水点滴水δ13CDIC存在很大差异，可能与上覆土壤受到严重破坏导致基岩贡献率相对较高有关，而其中的几个滴水与相应沉积物的同位素不平衡可能是沉积速率太慢或沉积间断所致；XND尽管土壤水与JJD的有相似的特征，但其洞穴滴水平均δ13CDIC之间基本一致且与相应沉积物接近同位素平衡。因此，4个洞穴中，LFD可能是最为适合进行高分辨率和短时间尺度（如季节甚至月份）研究的洞穴。另外，对于文中出现的滴水（上）δ13CDIC偏重于滴水（下）的现象以及土壤中水气平衡的影响因素等还有待今后进一步研究。 4. 研究的4个洞穴系统大气降雨尽管主要受东亚季风控制，但来源不完全一致，还不同程度地受西南夏季风等影响。LFD和QXD受东亚季风影响程度相对高于XND和JJD，西南季风的影响程度恰好相反。 5. 尽管地表蒸发作用对表层（10cm以上）土壤水δ18O有一定的控制作用，但是较深（如10cm以下）土壤水基本不受影响；同位素示踪结果显示，土壤水和洞穴滴水对大气降水均有响应，但响应时间不一，可能与上覆物质（植被、土壤和基岩等）结构构造等控制的水文学特征和有效大气降水量等有关；喀斯特土壤的高度异质性导致土壤水运移机制的不同，从而影响混合作用的过程，最终导致洞穴系统同期土壤水δ18O存在一定差异；雨水在下渗过程中的不同来源水混合作用，是不同类型水δ18O时间上变化幅度不同的主要原因；同一洞穴不同滴水δ18O之间的差异可能与水文学特征不同有关；水化学性质（如SIC）控制沉积物的沉积过程从而影响同位素平衡。 由此可见，利用研究的4个洞穴系统中洞穴次生化学沉积物中氧同位素恢复和重建古降水量的高分辨率短时间变化是可行的。但我们也应注意到，在利用洞穴次生化学沉积物恢复和重建古降水量之前有必要寻找合适的方法（如利用Hendy法则等）判断是否达到同位素平衡。不是所有点沉积物都真实地记录着滴水（大气降水）同位素信号的，尤其在QXD和JJD中，一半左右的滴水点沉积物没有达到同位素平衡。这些均显示出在高分辨率短时间尺度古气候研究中，了解沉积物的形成过程对于准确解译洞穴过去环境变化具有重要意义。

岩溶洞穴系统稳定碳同位素演化的地球化学过程及其环境意义

稳定碳同位素作为环境替代指标己经在不同的载体上得到了广泛运用，例如树轮。泥炭、碳酸盐岩等。目前岩溶学者也逐渐开始运用洞穴次生化学沉积物中的稳定碳同位素探讨古气候环境的变迁史，例如植被的更替、大气CO。的浓度变化等。然而由于缺乏该指标在岩溶洞穴系统中形成机理的研究，使得该环境替代指标的运用非常有限。本论文在贵州岩溶地区选择了上覆植被分别为原始森林。灌丛草坡、草坡和石漠化的凉风洞、七星们、犀牛洞、将军们作为研究对象，对岩溶洞穴系统稳定碳同位素的时空演化规律进行了详细的分析，得出以下几点认识：一．洞穴系统稳定碳同位素对地表气候环境的响应通过对4个不同生境洞穴系统的研究，认为洞穴系统稳定碳同位素可以很好地将原始森林植被同其它植被类型区分开；但是不能很好地区分植被退化的过渡类型如灌丛、草坡以及石漠化等。表明石笋的δ13C值在一定情况下可以用来探讨地表植被的变化。但要做更精确的反演需要在加深机理方面的研究。通过同一洞穴不同滴水点的对比研究，发现不同滴水点沉积物的稳定碳同位素存在差异，并且差异还比较大。表明用石笋的δ13C值对古气候环境进行重建时需要慎重考虑滴水点的详细情况。在这种情况下，应该对稳定碳同位素的地球化学过程进行详细研究，尤其应该结合水化学数据对水的运移途径进行深入研究，才能合理地运用稳定碳同位素对洞顶的植被情况进行正确的反演。洞穴滴水和塘中水DICδ13C值和月累积降雨量成相反的变化趋势；地表泉水、土壤水DICδ13C值。土壤CO2、土壤呼吸δ13C值和月累积降雨量的变化在多数时候具有一致的变化趋势。总体而言，洞穴系统水样DICδ13C值对月平均气温的响应不是很明显。只有洞穴塘中水DICδ13C值和月平均气温成相反的变化规律；土壤呼吸CO2δ13C值对月均温响应较为明显：月平均温度越高，土壤呼吸CO2δ13C值越偏轻，反映了温度较高的时候土壤层中的生物活动较强烈。二．岩溶洞穴系统稳定碳同位素的时间演化犀牛洞、将军洞。七星洞10月份植被δ13C值样品的δ13C值比7月份样品的δ13C值偏重。犀牛洞和将军洞土壤空气CO。的δ13C值在8月份出现了一个峰值，以前在清镇红枫湖生态站草地土壤剖面所作的工作8月份的值也同样偏重。在6月份时，凉风洞和七星洞存在一个较为明显的低值，与微生物和植物的强烈呼吸作用有关。土壤呼吸气CO2的δ13C值在6月份出现了明显的低值，和土壤CO。的变化趋势一致。4个洞穴空气CO2的δ13C值在8、9月份有一个低值。七星洞和外界的连通性最好，其洞穴空气CO2δ13C值随时间的变化最不明显，而凉风洞与夕十界的连通性最差，洞穴空气CO2δ13C值的变化幅度最大。土壤水DIC的δ13C值8月份存在一个峰值，在9月份的时候存在一个低值。七星洞地表泉水DIC的δ13C值自6月份开始有逐渐偏重的趋势，到8月份达到一个不甚明显的峰，这个峰值在凉风洞的表层泉中也略有体现。和土壤水比较，地表泉水的不同点在于低值不出现在9月份，而是出现在10月份，相对而言滞后1个月。原因可能是表层泉水所到达的深度比土壤水深；土壤强烈呼吸作用的响应要比土壤水慢。各个洞穴的滴7RDICδ13C值随时间退推移出现了不同的变化规律，可能与滴水的来源和途径不同有关。4个洞穴塘中水DIC的δ13C值统一在7月份达到了最低值；之后DIC的δ13C值逐渐偏重。三．岩溶洞穴系统稳定碳同位素的空间演化植被样不同部位的δ13C值总体上逐渐偏重的顺序是皮一叶一枝一根～干，说明植物不同部位的稳定碳同位素存在差异。随着凉风洞一七星洞一犀牛4同一将军洞的顺序，植被δ13C值逐渐变重；反映了地表植被由C3植物向C3＋C4植物的过渡，指示了生态环境由原始森林→石漠化方向的退化。土壤有机碳的δ13C值基本继承地表植物δ13C值的特征。没有发生植被更替上壤剖面上有机碳的δ13C值随着深度的增加逐渐偏重；植被发生了变化的土壤剖面则可能出现与正常规律相反的变化情况。土壤剖面上CO2的δ13C值自地表；句下逐渐变轻，在一定深度后大致趋于稳定；土壤呼吸CO2δ13C值位于土壤CO2δ13C值的变化范围；土壤呼吸CO2δ13C值的变化规律和植被δ13C值的变化在空间上具有一致性。土壤水DIC的δ13C值比土壤CO2值偏重；泉水DIC的δ13C值比土壤水DIC的δ13C值偏重，原因是泉水可能己经渗入到基岩层之后再出露到地表，已经混入了部分基岩无机碳的成分。四个研究洞穴系统盖板基岩的δ13C值变化范围大约在2－3‰之间。凉风洞和犀牛洞不同滴水点滴水的δ13C值相对比较稳定，七星们和将军洞的变化比较大。洞穴塘中水DIC的δ13C值和洞穴滴水相比明显偏重，原因为洞穴塘中水经历了强烈的蒸发作用；满后水比滴前水整体偏重。从洞日往内洞穴空气CO2的δ13C值逐渐偏轻，并且洞穴空气CO2δ13C值继承了洞穴水样DICδ13C值的变化趋势。洞穴化学次生沉积物的δ13值：同一个洞穴中不同滴水点化学沉积物的δ13C值存在差异，但是和滴水DIC的δ13C值相对应，反映了沉积物δ13C值对洞穴滴水DICδ13C值的继承，沉积物δ13C值比滴水DICδ13C值偏重。最新鲜沉积物和比较老的沉积物之间的对比偏轻1-2‰，沉积物中的δ13C值有可能发生沉积期后的变化。

Methodenentwicklung zur Spurenanalyse organischer Biomarker in Speläothemen und Tropfwasser mittels Flüssigchromatographie-(HR-)Massenspektrometrie

Speläotheme und Tropfwasser spielen eine wichtige Rolle bei der Erforschung von Naturerscheinungen. Während sich bisherige Studien größtenteils auf anorganische Proxies konzentrieren, wächst das Interesse an organischen Biomarkern, vor allem Lipidbiomarkern.rnAufgrund dessen wurde eine neue Methode entwickelt, um Fettsäuren mit einer geradzahligen Kettenlänge C12-C20 in Speläothem- und Tropfwasserproben zu bestimmen. Dabei kam eine Festphasenextraktion mit anschließender HPLC-MS Messung zum Einsatz. Die Methode wurde auf mehrere Proben aus der Herbstlabyrinth-Adventhöhle angewendet. Die benötigte Probenmenge wurde im Vergleich zu früheren Studien von etwa 4 L auf 60-100 mL bei Tropfwasser und von 10-100 g auf ca. 0,5-3,5 g bei Stalagmitproben reduziert. Es konnte eine interne Variation der Analyten festgestellt werden. Korrelationen der Fettsäuren ließen vermuten, dass C12-C18 von der gleichen Quelle stammen, während C20 teilweise andere Quellen besitzt. Korrelationen mit δ13C verdeutlichten, dass es einen Zusammenhang zwischen der Vegetationsdichte und dem Vorkommen der Fett-säuren in dem Probenmaterial gibt. Vergleiche mit Mg Konzentrationen zeigten, dass die Niederschlagsmenge zwar den Transport der Fettsäuren mit dem Tropfwasser beeinflusst, allerdings nicht ihre ermittelte Konzentration in Stalagmitproben. Die ermittelten Ergebnisse ließen darauf schließen, dass eindeutigere Vegetations-Proxies als die Fettsäuren gefunden werden müssen. Ein erstmaliges non-target screening verdeutlichte, dass Lignine und Tannine als charakteristische Biomarker eingesetzt werden können.rn

Late pleistocene to holocene composite speleothem O-18 and C-13 chronologies from south island, new Zealand-did a global younger dryas really exist?

Oxygen and carbon data from eight stalagmites from northwest South Island are combined to produce composite records of delta(18)O and delta(13)C from 23.4 ka to the present. The chronology is anchored by 43 thermal ionization mass spectrometry (TIMS) uranium series ages. Delta O-18 values are interpreted as having a first order positive relationship to temperature, but also to be influenced by precipitation in a complex manner. Delta C-13 is interpreted as responding negatively to increases in atmospheric CO, concentration, biological activity and precipitation amount. Six climatic phases are recognized. After adjustment of 1.2parts per thousand for the ice volume effect, the delta(18)O record between 23 and 18 ka varies around -3.72parts per thousand compared to the Holocene average of -3.17parts per thousand. Late-glacial warming commenced between 18.2 and 17.8 ka and accelerated after 16.7 ka, culminating in a positive excursion between 14.70 and 13.53 ka. This was followed by a significant negative excursion between 13.53 and 11.14 ka of up to 0.55parts per thousand depth that overlapped the Antarctic Cold Reversal (ACR) and spanned the Younger Dryas (YD). Positive delta(18)O excursions at 11.14 ka and 6.91-6.47 ka represent the warmest parts of the Holocene. The mid-Holocene from 6 to 2 ka was marked by negative excursions that coincide with increased glacial activity in the South Island. A short positive excursion from 0.71 to 0.57 ka was slightly later than the Medieval Warm Period of Europe. Delta C-13 values were high until 17.79 ka after which there was an abrupt decrease to 17.19 ka followed by a steady decline to a minimum at 10.97 ka. Then followed a general increase, suggesting a drying trend, to 3.23 ka followed by a further general decline. The abrupt decrease in delta-values after 17.79 ka probably corresponds to an increase in atmospheric CO2 concentration, biological activity and wetness at the end of the Last Glaciation, but the reversal identified in the delta(18)O record from 13.53 to 11.14 ka was not reflected in delta(13)C changes. The lowest delta(13)C values coincided with the early Holocene climatic suboptimum when conditions were relatively wet as well as mild. Major trends in the delta(18)O(c) record are similar to the Northern Hemisphere, but second order detail is often distinctly different. Consequently, at the millennial scale, a more convincing case can be made for asymmetric climatic response between the two hemispheres rather than synchronicity. (C) 2004 Elsevier B.V. All rights reserved.

Petrologia das fraturas associadas a feições típicas de dissolução hipogênica na Formação Salitre, Bacia de Irecê, Bahia, Brasil

The recognition of karst reservoirs in carbonate rocks has become increasingly common. However, most karst features are small to be recognized in seismic sections or larger than expected to be investigated with borehole data. One way forward has been the study of analogue outcrops and caves. The present study investigates lithofacies and karst processes, which lead to the generation of the largest system of caves in South America. The study area is located in the Neoproterozoic Una Group in central-eastern Brazil. This province comprises several systems of carbonate caves (Karmann and Sanchéz, 1979), which include the Toca da Boa Vista and Barriguda caves, considered the largest caves in South America (Auler and Smart, 2003). These caves were formed mainly in dolomites of the Salitre Formation, which was deposited in a shallow marine environment in an epicontinental sea (Medeiros and Pereira, 1994). The Salitre Formation in the cave area comprises laminated mud/wakestones, intraclastic grainstones, oncolitic grainstones, oolitic grainstones, microbial laminites, colunar stromatolites, trombolites and fine siliciclastic rocks (marls, shales, and siltites). A thin layer and chert nodules also occur at the top of the carbonate unit. Phosphate deposits are also found. Our preliminary data indicate that folds and associated joints control the main karstification event at the end of the Brasiliano orogeny (740-540 Ma). We recognized five lithofacies in the cave system: (1) Bottom layers of grainstone with cross bedding comprise the main unit affected by speleogenesis, (2) thin grainstone layers with thin siltite layers, (3) microbial laminites layers, (4) layers of columnar stromatolites, and a (5) top layer of siltite. Levels (1) to (3) are affected by intense fracturing, whereas levels (4) and (5) seal the caves and have little fracturing. Chert, calcite and gipsite veins cut across the carbonate units and play a major role in diagenesis. Our preliminary study indicate that hypogenic spelogenesis is the main process of karst development and contributed significantly to the generation of secondary porosity and permeability in the carbonate units.

Evidence of homing following translocation of long‐tailed bats (Chalinolobus tuberculatus) at Grand Canyon Cave, New Zealand

Homing behaviour in the New Zealand long-tailed bat (Chalinolobus tuberculatus), a temperate insectivorous species, was investigated at Grand Canyon Cave, central North Island. A pilot study of nine adult male bats was conducted to determine whether use of the cave was regular enough for a homing study. Eight bats returned to the cave over the 3 week monitoring period, six on the night of the following release. Nine additional bats carrying radio transmitters were then released at three sites (three at each site) c.5, 10 and 20km due east of the border of, and outside the population's known familiar area respectively. All but one of these nine was subsequently detected at the cave. Results suggest that adult long-tailed bats are able to return home following displacement both inside and outside their familiar area. Implications of these findings for translocations of bats and the possessions of a potential long distance navigation system by this species are discussed.

Case Study: Interacting with Volumetric Medical Datasets in Networked CAVE Environments

Virtual Reality (VR) is widely used in visualizing medical datasets. This interest has emerged due to the usefulness of its techniques and features. Such features include immersion, collaboration, and interactivity. In a medical visualization context, immersion is important, because it allows users to interact directly and closelywith detailed structures in medical datasets. Collaboration on the other hand is beneficial, because it gives medical practitioners the chance to share their expertise and offer feedback and advice in a more effective and intuitive approach. Interactivity is crucial in medical visualization and simulation systems, because responsiveand instantaneous actions are key attributes in applications, such as surgical simulations. In this paper we present a case study that investigates the use of VR in a collaborative networked CAVE environment from a medical volumetric visualization perspective. The study will present a networked CAVE application, which has been built to visualize and interact with volumetric datasets. We will summarize the advantages of such an application and the potential benefits of our system. We also will describe the aspects related to this application area and the relevant issues of such implementations.

A flow system for the on-line quantitative measurement of the retention of dosage forms on biological surfaces using spectroscopy and image analysis

Measuring the retention, or residence time, of dosage forms to biological tissue is commonly a qualitative measurement, where no real values to describe the retention can be recorded. The result of this is an assessment that is dependent upon a user's interpretation of visual observation. This research paper outlines the development of a methodology to quantitatively measure, both by image analysis and by spectrophotometric techniques, the retention of material to biological tissues, using the retention of polymer solutions to ocular tissue as an example. Both methods have been shown to be repeatable, with the spectrophotometric measurement generating data reliably and quickly for further analysis.

Growth rates in modern speleothems from Santana Cave, Brazil, by the Pb-210-method

The Santana Cave is located at the Upper Ribeira Touristic State Park (PETAR-Parque Estadual Turistico do Alto Ribeira) in southern São Paulo State, Brazil. This paper describes Pb-210 activity concentration data in soda straw stalactites samples collected at Salao das Flores in Santana Cave that is a fossil tributary of the cave river. Non-expensive alpha counting following some analytical steps for extracting and depositing Pb-210 were used for providing the Pb-210 data. In the analyzed samples, Pb-210 values of increasingly older samples fitted an exponential curve, thus suggesting that the production of Pb-210 has been constant with time. Also, the near-ideal fit indicated that the growth was uniform and there was no break in the continuous growth. The soda straw growth rates were determined from the best fit to the exponential curve through the Pb-210 activity concentration. The results of the measurements allowed estimate a longitudinal rate corresponding to 1.3 mm/yr and a lateral rate of 0.01 mm/yr, which permitted calculate times of 70 years and 317-498 years for their formation, respectively. The lateral growth rate is compatible with values from studies of chemical weathering rates held under laboratory and natural conditions. (C) 2011 Elsevier Ltd. All rights reserved.

AN ANATOMICAL STUDY OF THE LATEROTRIGEMINAL VENOUS SYSTEM

The middle cranial fossa of 100 cadavers were dissected under stereoscopic loupe in order to identify and systematize the venous vessels located along the lateral margin of the trigeminal cave. The author found that at the sensitive root and trigeminal ganglion level a dural venous canal was present in most individuals examined and that the upper side of this canal communicated with the superior petrosal sinus. However, at the level of the lateral border of the intracranial segment of the mandibular nerve, venous lacunae were found to prevail, and these lacunae communicated with several other venous formations in the peritrigeminal region. The author concludes that the venous vascularization of this area constitutes a major risk in surgical interventions made in the middle cranial fossa. In addition, it is a relevant factor in the hemodynamics of the intracranial circulation.

Design and evaluation of an advanced virtual reality system for visualization of dentistry structures

This paper presents the development of an application created to assist the teaching of dental structures, generate rich content information and different manners of interaction. An ontology was created to provide semantics informations for virtual models. We also used two devices gesture-based interaction: Kinect and Wii Remote. It was developed a system which use intuitive interaction, and it is able to generate three dimensional images, making the experience of teaching / learning motivating. The projection environment used by the system was called Mini CAVE. © 2012 IEEE.