Airborne non-contact and contact broadband ultrasounds for frequency attenuation profile estimation of cementitious materials.

In this paper, the study of frequency-dependent ultrasonic attenuation in strongly heterogeneous cementitious materials is addressed. To accurately determine the attenuation over a wide frequency range, it is necessary to have suitable excitation techniques. We have analysed two kinds of ultrasound techniques: contact ultrasound and airborne non-contact ultrasound. The mathematical formulation for frequency-dependent attenuation has been established and it has been revealed that each technique may achieve similar results but requires specific different calibration processes. In particular, the airborne non-contact technique suffers high attenuation due to energy losses at the air-material interfaces. Thus, its bandwidth is limited to low frequencies but it does not require physical contact between transducer and specimen. In contrast, the classical contact technique can manage higher frequencies but the measurement depends on the pressure between the transducer and the specimen. Cement specimens have been tested with both techniques and frequency attenuation dependence has been estimated. Similar results were achieved at overlapping bandwidth and it has been demonstrated that the airborne non-contact ultrasound technique could be a viable alternative to the classical contact technique.

Optimized ultrasonic attenuation measures for non-homogeneous materials.

In this paper the study of frequency-dependent ultrasonic attenuation in strongly heterogeneous materials is addressed. To determine the attenuation accurately over a wide frequency range, it is necessary to have suitable excitation techniques. Three kinds of transmitted signals have been analysed, grouped according to their bandwidth: narrowband and broadband signals. The mathematical formulation has revealed the relation between the distribution of energy in their spectra and their immunity to noise. Sinusoidal and burst signals have higher signal-to-noise ratios (SNRs) but need many measurements to cover their frequency range. However, linear swept-frequency signals (chirp) improve the effective bandwidth covering a wide frequency range with a single measurement and equivalent accuracy, at the expense of a lower SNR. In the case of highly attenuating materials, it is proposed to use different configurations of chirp signals, enabling injecting more energy, and therefore, improving the sensitivity of the technique without a high time cost. Thus, if the attenuation of the material and the sensitivity of the measuring equipment allows the use of broadband signals, the combination of this kind of signal and suitable signal processing results in an optimal estimate of frequency-dependent attenuation with a minimum measurement time.

Ultrasonic characterization of GRC with high percentage of fly ash substitution.

New applications of non-destructive techniques (NDT) with ultrasonic tests (attenuation and velocity by means of ultrasonic frequency sweeps) have been developed for the characterization of fibre-reinforced cementitious composites. According to new lines of research on glass-fibre reinforced cement (GRC) matrix modification, two similar GRC composites with high percentages of fly ash and different water/binder ratios will be studied. Conventional techniques have been used to confirm their low Ca(OH)(2) content (thermogravimetry), fibre integrity (Scanning Electron Microscopy), low porosity (Mercury Intrusion Porosimetry) and good mechanical properties (compression and four points bending test). Ultrasound frequency sweeps allowed the estimation of the attenuation and pulse velocity as functions of frequency. This ultrasonic characterization was correlated successfully with conventional techniques.

[Cesarean section in a patient with acute myocardial infarction during pregnancy]. / Cesárea en una paciente con infarto agudo de miocardio durante la gestación.

Maternal heart disease during pregnancy is the main cause of obstetric morbidity and mortality. We report the case of a 40-year-old woman with a history of myocardial infarction and percutaneous transluminal coronary angioplasty. The patient suffered a second heart attack and received pharmacologic treatment. After admission, she was seen to be 29 weeks pregnant. Delivery was by cesarean section under progressive epidural block without complications. We review the medical, obstetric, and anesthetic implications of myocardial infarction during pregnancy. The management of such patients should be multidisciplinary and decisions about delivery should be taken based on obstetric considerations.

Cesárea en una paciente con infarto agudo de miocardio durante la gestación / Cesarean section in a patient with acute myocardial infarction during pregnancy

La enfermedad cardiaca maternal durante el embarazo es la primera causa de morbimortalidad no obstétrica. Presentamos el caso de una mujer de 40 años con antecedente de infarto de miocardio que recibió angioplastia coronaria transluminal percutánea. La paciente sufrió un segundo episodio de infarto y recibió tratamiento farmacológico. Durante el ingreso se descubrió que se encontraba en la semana 29 de gestación. El parto se realizó por cesárea bajo bloqueo epidural progresivo sin complicaciones. Este artículo realiza una revisión del infarto de miocardio durante el embarazo y sus implicaciones médicas, obstétricas y anestésicas, concluyendo que el manejo de dichas pacientes ha de ser multidisciplinar y que la decisión sobre el parto ha de tomarse en base a indicaciones obstétricas

Maternal heart disease during pregnancy is the main cause of obstetric morbidity and mortality. We report the case of a 40-year-old woman with a history of myocardial infarction and percutaneous transluminal coronary angioplasty. The patient suffered a second heart attack and received pharmacologic treatment. After admission, she was seen to be 29 weeks pregnant. Delivery was by cesarean section under progressive epidural block without complications. We review the medical, obstetric, and anesthetic implications of myocardial infarction during pregnancy. The management of such patients should be multidisciplinary and decisions about delivery should be taken based on obstetric considerations

Influencia de la aprotinina en el sangrado postoperatorio de la artroplastia total de rodilla / Effect of aprotinin on postoperative bleeding in total knee replacement

Objetivo. Estudiar el efecto de la administración de aprotinina sobre el sangrado postoperatorio de la artroplastia total de rodilla. Material y método. Estudio retrospectivo sobre 64 pacientes divididos en un grupo de casos (30 pacientes) que recibió una dosis de aprotinina de 2 x 106 unidades inhibidoras de kalicreína (KIU), y un grupo de control (34 pacientes) que no recibió ninguna dosis del fármaco. Se estudiaron la hemoglobina, el hematocrito y el número de plaquetas en hemogramas preoperatorio y postoperatorio (entre las 6 y 12 horas y a las 24 horas de la intervención). Se registró el volumen de sangre obtenido por los drenajes de Redon. Se contabilizó el número de concentrado de hematíes transfundidos en cada caso. Resultados. Los pacientes a los que se administró aprotinina tuvieron un menor descenso de los valores de hemoglobina y hematocrito y un menor volumen de sangre recogido en los drenajes de Redon que el grupo control. Durante el postoperatorio se transfundió a menos pacientes del grupo de casos que del grupo de control. Las diferencias entre los valores estudiados de ambos grupos resultaron estadísticamente significativas. Conclusión. La administración de aprotinina contribuye a reducir el descenso de hemoglobina y hematocrito, así como las pérdidas en los drenajes y la administración de hemoderivados en el postoperatorio de la artroplastia total de rodilla

Aim. To study the effect of the administration of aprotinin on postoperative bleeding in total knee replacement (TKR). Materials and methods. A retrospective study was performed on 64 patients divided into a treatment group (30 patients) that received a dose of aprotinin of 2x106 inhibitory units of kalicrein and a control group (34 patients) that did not receive any drug. Different variables were studied: hemoglobin, hematocrit, and platelets in preoperative and postoperative (6-12 hs and 24 hs) hemograms. The volume of blood in Redon high-vacuum drainage was registered. The number of packed red blood cell concentrate (pRBC) units transfused were also registered. Results. The patients that received aprotinin had a smaller decrease of hemoglobin and hematocrit than the patients in the control group. The volume of blood collected in the Redon drainage for these patients was also smaller than in the control group. During the postoperative period fewer patients in the treated group received transfusions than in the control group. The differences in the variables studied in both groups were statistically significant. Conclusion. The administration of aprotinin helps reduce the fall in hemoglobin and hematocrit, the blood losses into drainage and the administration of transfusions during the postoperative period in TKR

On estimating the center frequency of ultrasonic pulses.

In this paper we propose a new technique for estimating the center frequency of the ultrasound pulse from records of backscattering noise. We start by considering that the conventional maximum frequency method can be seen as a filtering (differentiator) of the pulse spectrum magnitude followed by a searching for the zero-crossing value. The new approach replaces the differentiator by a Hilbert transformer. We show in the paper that the proposed method has less variance than the maximum frequency method. In particular, we analyse the performance assuming that the real cepstrum method is used for extracting pulse spectrum magnitude. We give an upper bound for the variance reduction when practical criteria are applied for fitting the cepstrum cut-off frequency. The analytical work is verified by real and simulated data.

The os coxae of a digging form of the northern water vole, Arvicola terrestris (Rodentia, Arvicolidae).

Data on the morphology, relative growth and sexual dimorphism of the os coxae of a digging form of the northern water vole Arvicola terrestris (A.t. monticola) are given. Two hundred ninety-nine specimens (146 males and 153 females) caught in the Aran Valley (Spanish Pyrenees) were analyzed. The specimens were distributed into six classes of relative age, according to the skull morphology, kind of coat, moulting state, weight and sexual state. The morphological features of the os coxae in these specimens are similar to those described in other species of Arvicolidae. The hormonal effect upon the pelvis in adult females during pregnancy and parturition leads to the appearance of marked intersexual differences in the obturator foramen length, the pubis length, the pelvis length and, specially, in the pelvis height and the pubis width. By means of Becker's and Dunmire's procedures both sexes can be correctly discriminated in a 78.87 and a 76.4% respectively. Conjugating the variation patterns obtained with Becker's index and the pelvis height, we have obtained a more effective method of sexual differentiation (an 85.51% of correct discrimination).

[A new Typhloceras from Catalonia (author's transl)]. / Un Typhloceras nouveau de Catalogne (Siphonaptera, Hystrichopsyllidae).

T. favosus claramuntae, parasitic on the shrew Crocidura russula russula is described from Isle Meda Gran, Girona (Spain). This subspecies can be separated by morphology and chaetotaxy of sternit VIII. Only the male is actually known.

[Contribution to study of Ixodidae (Acarina, Ixodoidea) in Cantabric Mountains (Spain) (author's transl)]. / Contribution à l'étude des Ixodidae (Acarina, Ixodoidea) des Monts Cantabriques (Espagne)

Five Ixodidae species parasites of small mammals have been identified in North-western Spain and particularly on the cantabrique Mountains. The authors mention that among these species there are Ixodes acuminatus (Neumann, 1901) and Ixodes trianguliceps (Birula, 1895), which according to their own knowledge, have never been noticed in the Iberian Peninsula so far.