A XVIII century polychrome porcelain, of complex layered structure has been analysed by using several techniques. The studied porcelain shard was a fragment of a flooring tile from the “Casita del Labrador”, a small palace located in Aranjuez, near Madrid. The high spatial resolution of the α-PIXE technique, an appropriate choice of the beam energies and the use of an external micro-beam have allowed to determine the composition of the constituent layers almost free from interferences, which was not possible with other analytical techniques. The nature of the pigments in particular is now well understood. PIXE analysis was confirmed by traditional, although destructive, XRD, XRF and SEM-EDS analyses.

This paper deals with the implementation of five multivariable adaptive, as well as classical, control strategies in an industrial grinding plant. The extended horizon, pole-placement, model reference, direct Nyquist Array and sequential loop closing algorithms were studied and implemented at CODELCO-Andina's copper grinding plant, with each of them delivering good performance. The 2×2 system chosen to be controlled has the percentage of solids (percentage of +65 mesh) fed to the hydrocyclones and the level of the sump as output variables, and the water flow added to the sump and the pump speed as input variables. The adaptive extended horizon algorithm performs the best, although all five strategies considerably improve the actual operation of the plant which consists of only one control loop. After a comparison amongst the control strategies, a brief economic impact analysis is performed to support the claim that multivariable control algorithms substantially improve the operation of the grinding plant, maintaining the percentage of solids (percentage over mesh 65) around a pre-specified value (optimal for practical purposes); thus obtaining interesting economic benefits.

This paper presents results following the application of a sub-optimal control scheme, both through simulation and in situ, from the operation of Section C of the CODELCO-Andina copper concentrator plant. The algorithm permits the determination of the necessary control action at each instant of time in order to maximize a defined plant performance index. The main objective of the algorithm is to maximize the mineral tonnage processed by the section, subject to it not exceeding a predetermined value establishes! for the operation conditions of the mills, while at the same time maintaining constant the mass fraction over 65 mesh (212 [microns]) in the overflow of the hydrocyclones, at a value within the operational requirements of the flotation stage. The performance index is defined in terms of; the percentage of pulp solids fed to the hydrocyclones of each line of ball mills, penalty functions to prevent electric power to the ball mills ,falling below the lower limit (so as not to enter the overload region), the tonnage processed in the section, and, since water is a scarce resource, a term considering the water added to each sump is also included. The scheme is first studied and adjusted in a simulator of a concentrator plant similar to that used in the industrial application. For plant implementation, a PC software program, denoted CONMOL, is developed in TurboPascal for Windows. This software allows plant applications to be carried out through a communications interface. Finally, the results of two tests performed on Section C of the CODELCO-Andina copper concentrator plant are shown where the control is applied over 3 and 5.5 hours respectively.

Particle size measurement, specially in product streams, is fundamental to control of a grinding circuit. In this paper, the design of a soft-sensor in an actual grinding plant is addressed, with the purpose of increasing the availability of such measurement. The system is designed to substitute the momentary unavailability of the real sensor, either because it has failed or it is in calibration or because it is time shared by several parallel grinding lines. An ARMAX model structure is determined using the stepwise regression method. Starting with a list of the presumably correlated candidate variables, the method selects, one by one and in a systematic manner, the variables that best model the measurement to be replaced. Not only the single measurements are included in the list of candidates, but also combinations of such measurements having physical significance. A phenomenological model has been built with the purpose of determining these combinations. It turns out that, in most of the cases, the components of combined measurements were selected by the method, instead of the single measurements. Actual grinding plant data is used to determine the model structure, to estimate the model parameters and to test the predictive capability of the soft-sensors developed. Good results are obtained during periods of up to 24 h of the particle size soft-sensor operation. (C) 1998 Elsevier Science S.A. All rights reserved.

Apoptosis seems to play an important role in the decline of CD4+ T-cells in patients infected with HIV-1. Moreover, extensive interest in apoptosis comes from the observation that it correlates both with the progression and the severity of HIV-1 infection. A cross-sectional study was made to evaluate whether such correlation may also extend to the early phases of ex vivo apoptosis, after 20 h of culture. DNA fragmentation, a parameter associated with apoptosis, was evaluated with the terminal deoxynucleotidyl-transferase-mediated dUTP nick end labelling (TUNEL) technique, which preferentially labels apoptosis in comparison to necrosis. The results obtained indicate that a negative correlation exists between the proportion of lymphocytes exhibiting DNA strand breaks and the absolute number of CD4+ T-cells per &μl. DNA fragmentation was significantly higher in patients with AIDS or advanced HIV-1 infection as compared to asymptomatic patients or seronegative individuals. No significant difference was found in relation to antiretroviral therapy. Furthermore, the addition of nicotinamide to the cultures significantly reduced DNA fragmentation of both in vitro HIV-1-infected MT-4 cells and lymphocytes from six HIV-1-seropositive individuals. The results of this study confirm that DNA fragmentation, as an early marker of apoptosis, correlates with the severity of HIV-1 infection and suggest that nicotinamide may be involved in the modulation of HIV-1-related apoptosis. © 1997 John Wiley & Sons, Ltd.

Central nervous system feedback loops centered on hypothalamic neurons control atrial natriuretic peptide (ANP). We evaluated the ANP response to arterial hypotension, isotonic blood volume expansion, and increase in plasma osmolality in 14 patients with multiple system atrophy (MSA). Seven of the patients were characterized by a lack of vasopressin response to hypotension (MSA type B), suggesting chronic sinoaortic denervation, and seven by a preserved response (MSA type A). Orthostatic hypotension decreased ANP in controls and type A patients, whereas ANP in type B was not affected. Isotonic saline infusion increased ANP and diuresis in controls and type A patients, whereas it did not affect ANP in type B. Osmotic load increased plasma osmolality and vasopressin in controls and MSA patients and ANP in controls and type A but not in type B patients. In MSA patients with altered afferent control of vasopressin, ANP secretion is not stimulated by blood volume expansion, osmotic load, or blood pressure, suggesting that afferent excitatory control plays a role in the release of ANP.

We evaluated plasma osmolality (pOsm), thirst, and vasopressin response to hypertonic saline infusion in 14 patients with multiple system atrophy (MSA). This disease is characterized by the degeneration of noradrenergic neurons in the central nervous system and severe orthostatic hypotension. Seven patients were also characterized by the lack of vasopressin response to hypotension (group B) and seven by a preserved response (group A). In group A pOsm rose from 290 +/- 2 to 312 +/- 6 mosmol/kgH2O, vasopressin from 0.9 +/- 0.3 to 5.7 +/- 0.5 pmol/l, and thirst from 1.1 +/- 0.1 to 8.7 +/- 1.1 cm on the visual analog scale. After saline, patients drank 1,215 +/- 150 ml of water (no different from healthy controls). In group B patients' pOsm rose from 296 +/- 3 to 325 +/- 6 mosmol/kgH2O and vasopressin from 1.2 +/- 0.1 to 19.6 +/- 0.4 pmol/l (P < 0.01 vs. group A and controls). Group B patients had no thirst during saline and drank little after the challenge (175 +/- 50 ml; P < 0.01 vs. group A and control). Forced drinking decreased vasopressin in patients before changes in pOsm, showing that inhibitory afferents from oropharyngeal mucosa were intact. In MSA patients with altered afferent control of vasopressin there is a dissociation between the osmotic control of thirst and the osmotic control of vasopressin.

Multiple system atrophy (MSA) is a heterogeneous group of central neurological degenerations often associated with diffuse deterioration of the hypothalamic cholinergic neurons. In the hypothesis of an altered cholinergic regulation of vasopressin release, we evaluated vasopressin response to metoclopramide (20 mg i.v.), a cholinomimetic agonist, in 12 MSA patients. In the same patients the hemodynamic and osmolal control of vasopressin was also evaluated. We found that MSA patients had significantly lower basal plasma vasopressin values and higher plasma osmolality than control subjects. However, they displayed a normal vasopressin response to osmotic stimulation. During head-up tilting, orthostatic hypotension occurred in all patients, and the vasopressin response to hypotension was severely blunted in 5 of 12 patients, thus demonstrating the presence of a lesion of the afferent noradrenergic pathways.Metoclopramide increased vasopressin in control subjects, whereas MSA patients did not display any increase in vasopressin. These results clearly indicate that cholinergic neurons that regulate vasopressin release are damaged in MSA. Such an alteration may be dissociated from the lesion of the afferent noradrenergic pathways. As a consequence of the altered vasopressin release, MSA patients show lower plasma vasopressin levels with consequent propensity to dehydration and hypovolemia, which may further aggravate their hypotension.

An in vitro cell line (SGT) derived from a mouse submaxillary gland adenocarcinoma (TGS) containing A and B viral particles maintained its oncogenicity only for newborn isogeneic hosts (C3H/He mice) immunosuppressed with antithymocyte serum. Inoculation into adult isogeneic animals did not cause tumor but provided partial protection against a challenge with TGS cells. The loss of oncogenicity for nonimmunosuppressed isogeneic hosts was accompanied by the acqusition of oncogenicity for adult, nonimmunosuppressed, xenogeneic hosts (golden hamsters) given subcutaneous inoculations of SGT cells on the back. From the tumor grown in the hamster, which is histologically similar to the original tumor of the mouse, an in vitro cell line (HWS) was derived. The comparative analysis of the 2 cell lines, SGT and HWS, led to the following conclusions: (a) the karyological pattern of the 2 cell lines in virtually the same; (b) the cell surface antigenic pattern is similar for the 2 cell lines, as determined by colony inhibition test and cytotoxicty test; (c) the cells of the HWS line behave serologically as a mouse-hamster hybrid, also as determined by colony inhibition and cytotoxicity tests; (d) both cell lines have only intracytoplasmic viral particles of the A type; and (e) agglutination with the plant lectins concanavalin A and wheat germ agglutinin occurs at lower concentrations of agglutinin for HWS cells than for SGT cells.

The oncogenicity of the cultivated cells of C3H/He mouse salivary gland adenocarcinoma is strictly correlated with the presence of the viral particles (Bittner). From both a quantitative and a qualitative standpoint the growth of the implanted tumor is similar to that observed in vivo and completely different from the mammary gland tumor which is also produced by Bittner virus. After 180 days the viral particles disappear from the cell and thereafter the cells are no longer oncogenic when implanted in isogeneic hosts.The early phases of culture are characterized by the epithelial feature of the tumor with a pseudotubular pattern. This feature is not modified with aging of the cultures, however a pseudo-flbroblastic transformation has occasionally been observed in very old samples. This step of evolution is characterized by “eosinophilic degeneration”.In the evolution of -tumor a relationship appears to exist between the disappearance of virus particles, the loss of oncogenicity and the presence of eosinophilic bodies.Die Onkogenität von Zellen des CH/He-Speicheldrüsen-Adenocarcinoms der Maus in Gewebekulturen ist eng verknüpft mit der Anwesenheit von Virus-partikeln (Bittner). Sowohl in quantitativer wie in qualitativer Hinsicht ist das Wachstum der implantierten Tumorzellen ähnlich dem beobachteten, jedoch vollkommen verschieden von dem des ebenfalls durch das Bittner-Virus hervorgerufenen Mammatumors. Nach 180 Tagen verschwinden die Viruspartikel aus den Zellen, wonach sie nicht mehr onkogen sind, wenn sie in isogene Wirtstiere transplantiert werden. Die frühen Phasen der Tumorzellen in der Gewebekultur sind durch epitheliale Beschaffenheit und Bildung von Pseudotubuli charakterisiert. Dieses Verhalten ändert sich auch nicht beim Altern der Kulturen, doch wurde gelegentlich eine pseudo-fibroblastische Umwandlung bei sehr alten Kulturen beobachtet. Dieser Vorgang ist durch eine „eosinophile Dengeneration” gekennzeichnet.In der Evolution des Tumors scheint eine Beziehung zwischen Verschwinden der Viruspartikel, dem Verlust der Onkogenität und dem Auftreten von eosinophilen Körperchen zu bestehen.

The oncogenicity of the cultivated cells of C3H/He mouse salivary gland adenocarcinoma is strictly correlated with the presence of the viral particles (Bittner). From both a quantitative and a qualitative standpoint the growth of the implanted tumor is similar to that observed in vivo and completely different from the mammary gland tumor which is also produced by Bittner virus. After 180 days the viral particles disappear from the cell and thereafter the cells are no longer oncogenic when implanted in isogeneic hosts.

Dai dati riferiti si mettono in evidenza due punti: il primo dimostra nel tumore in esame l'assenza di particelle virali e di effetto citopatico specifico per il virus polioma. Inoltre non si mettono in evidenza anticorpi fissanti il complemento o emoagglutinoinbenti per il virus polioma negli animali portatori di tumori. II secondo punto dimostra che durante il suo sviluppo il tumore della ghiandola salivare é incapace di indurre una risposta immunologica apprezzabile.