Analysis of cerebrospinal fluid from cattle with central nervous system disorders after storage for 24 hours with autologous serum

BACKGROUND: We compared the changes in cell morphology, total and differential cell counts between cerebrospinal fluid (CSF) samples analyzed within an hour of collection (fresh sample) and after the addition of autologous serum and storage for 24 h (stored sample) in 27 cattle with central nervous system disorders. RESULTS: There was a positive linear correlation between total and differential cell counts in the fresh and the stored samples. Cell morphology was preserved in all stored samples, except for increased vacuolization of mononuclear cells and cleaved nuclei of some small mononuclear cells. In the stored CSF samples, the total nucleated cell count and monocyte percentage were decreased (P = 0.01; P = 0.03), while the lymphocyte percentage was increased (P = 0.04). Mononuclear pleocytosis diagnosed in 20 fresh samples was cytologically confirmed in 12 of the 20 stored samples. In the remaining eight stored samples, the number of total nucleated cells was within the normal range. Neutrophilic pleocytosis was confirmed in all seven stored samples. The overall agreement rate between cytologic interpretation of the fresh and the stored CSF samples was 70 % (100 % for neutrophilic pleocytosis and 60 % for mononuclear pleocytosis). CONCLUSIONS: Adding 11 % of autologous serum to CSF samples might allow delayed analysis with a good agreement rate for CSF cytological interpretation. Caution is nonetheless warranted, as animal age, anamnesis, and neurological presentation need to be considered when interpreting stored CSF without pleocytosis. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12917-015-0502-x) contains supplementary material, which is available to authorized users

Analysis of microseismic signals and temperature recordings for rock slope stability investigations in high mountain areas

Abstract. The permafrost degradation is a probable cause for the increase of rock instabilities and rock falls observed in recent years in high mountain areas, particularly in the Alpine region. The phenomenon causes the thaw of the ice filling rock discontinuities; the water deriving from it subsequently freezes again inducing stresses in the rock mass that may lead, in the long term, to rock falls. To investigate these processes, a monitoring system composed by geophones and thermometers was installed in 2007 at the Carrel hut (3829 m a.s.l., Matterhorn, NW Alps). In 2010, in the framework of the Interreg 2007–2013 Alcotra project no. 56 MASSA, the monitoring system has been empowered and renovated in order to meet project needs. In this paper, the data recorded by this renewed system between 6 October 2010 and 5 October 2011 are presented and 329 selected microseismic events are analysed. The data processing has concerned the classification of the recorded signals, the analysis of their distribution in time and the identification of the most important trace characteristics in time and frequency domain. The interpretation of the results has evidenced a possible correlation between the temperature trend and the event occurrence. The research is still in progress and the data recording and interpretation are planned for a longer period to better investigate the spatial-temporal distribution of microseismic activity in the rock mass, with specific attention to the relation of microseismic activity with temperatures. The overall goal is to verify the possibility to set up an effective monitoring system for investigating the stability of a rock mass under permafrost conditions, in order to supply the researchers with useful data to better understand the relationship between temperature and rock mass stability and, possibly, the technicians with a valid tool for decision-making

Application of the cross correlation technique to microseismic data analysis for the identification of rock weakness zones

ISSN: 1972-155

Cross-analysis of temperature and slope microseismic activity for the Matterhorn peak study site (North-Western Alps)

A microseismic and a thermometric monitoring systems were installed, in the framework of the Interreg IIIA Alcotra “PERMAdataROC” project, on the Italian side of the Matterhorn peak, close to the J.A. Carrel hut. The analysis of a one year temperature recording has evidenced the influence of the slope exposure (north vs. south) on data recorded during different periods of the year and at different depths. In particular, given the Matterhorn peak geometry, approximately a pyramid, it emerges that the thermal gradient north/south and surface/depth can make possible an increase in stress concentration on weakness surfaces that pass through the rock mass and promotes instability events. The numerical correlation between a 6-months microseismic dataset and thermal data has evidenced a temporal concentration of the microseismic activity when temperature falls rapidly. While, no particular activity emerges when temperature raises. Integration of the microseismic monitoring with a thermometric system can then contribute in investigating rock response to climate forcing. Once fully developed and tested, this technique could become a helpful tool for warning in advance when climatic conditions that can favour a rock slope instability set up

A microseismic-based procedure for the detection of rock slope instabilities

The accumulation and spatial location of damage can lead to the progressive formation of macroscale discontinuities and the possible collapse of portions of rock slopes. Since rock fracturing is accompanied by the generation and transmission of elastic waves that travel through the affected material, an analysis procedure that is able to interpret data, recorded by means of a microseismic monitoring system, is presented in the paper. The procedure is made up of three main parts: the identification and grouping of similar events, the hypocenter location of grouped events and the cross-analysis of the spatial distribution of the source events with the structural setting of the investigated area. The application of this methodology to a dataset recorded by a monitoring system installed on the Matterhorn mountain has pointed out that this approach, which can allow the identification of similar signals arriving in different time periods from different or common areas, can contribute to recognizing areas subjected to a common rupture mechanism, which can concern one single fracture or a set of neighbouring fractures. If signals that are generated over time from a certain area have a waveform with similar characteristics, the rupture mechanism that causes the signals is the same. At this regard, a good knowledge of the local structural setting of the slope and of the characteristics of some documented rockfall events can contribute in supporting the above statement and help focus on areas where failures are kinematically possible

A heterogeneous multi-velocity model for the location of microseismic events in rock slopes

The development of faults in rock fractured material is coupled with the propagation of microcracks and the generation of elastic waves, which can be detected by a suitable microseismic monitoring system. As a consequence, an accurate re-location of microseismic events can give some important indications on the presence of weakness surfaces and on the possible evolution of a monitored area. Respect to the location of seismic events, the computation of the hypocenter of microseismic events requires an accurate knowledge of the velocity model, due to the different scale of the problem. In fact, the possible presence of an irregular topography (e.g mountain peak) and the spatial variability of the mass average characteristics in the subsurface require that a changing value of velocity in space can be assigned. In the present paper a new tool for heterogeneous multi-velocity model computation coupled with the location software NonLinLoc is described and applied to the case of the Matterhorn Peak (North Western Italian Alps), where a microseismic monitoring system was installed in the frame of the Interreg IIIA ALCOTRA “PERMAdataROC” project. A comparison among results obtained for the re-location of a set of hammer strokes - which were used to test the correct working of the microseismic network - with a homogeneous, a heterogeneous bi-value and a heterogeneous multi-value velocity models is here presented and discussed. In particular, obtained results evidence the importance of a correct distribution of microseismic sensors in space and the improvement in location quality when a heterogeneous multi-velocity model is used

A Procedure to Determine the Optimal Sensor Positions for Locating AE Sources in Rock Samples

Within a research work aimed to better understand frost weathering mechanisms of rocks, laboratory tests have been designed to specifically assess a theoretical model of crack propagation due to ice segregation process in water-saturated and thermally microcracked cubic samples of Arolla gneiss. As the formation and growth of microcracks during freezing tests on rock material is accompanied by a sudden release of stored elastic energy, the propagation of elastic waves can be detected, at the laboratory scale, by acoustic emission (AE) sensors. The AE receiver array geometry is a sensitive factor influencing source location errors, for it can greatly amplify the effect of small measurement errors. Despite the large literature on the AE source location, little attention, to our knowledge, has been paid to the description of the experimental design phase. As a consequence, the criteria for sensor positioning are often not declared and not related to location accuracy. In the present paper, a tool for the identification of the optimal sensor position on a cubic shape rock specimen is presented. The optimal receiver configuration is chosen by studying the condition numbers of each of the kernel matrices, used for inverting the arrival time and finding the source location, and obtained for properly selected combinations between sensors and sources positions

Application of a multiplet-location coupled technique to microseismic data for identification of rock slope active surfaces

In rock slope analysis, formation and growth of microcracks are usually coupled with the propagation of elastic waves that can be detected by a suitable microseismic monitoring system. The correct analysis and interpretation of the recorded activity can provide information on the size and the type of the rupture mechanisms. A combination of the coherency computation and the source location techniques, typically used in seismic signal processing, is here proposed to this aim. The application to a microseismic dataset recorded by the microseismic monitoring system installed on the Matterhorn Peak, has evidenced the effectiveness of this approach. In particular the coherency has allowed to identify a set of similar appearing events, while the location of the corresponding hypocenters has evidenced the alignment of the sources on a planar surface, whose orientation is closed to the orientation of a discontinuity system resulting from a morphostructural surve