All laser-assisted heteroepitaxial growth of Si0.8Ge0.2 on Si(100): Pulsed laser deposition and laser induced melting solidification

3 pages, 3 figures.The growth of heteroepitaxial Si0.8Ge0.2 films on Si(100) by a novel all laser-assisted technique using only ArF excimer laser radiation is demonstrated. Amorphous 30 nm thick films are grown by pulsed laser deposition from alternating pure Si and Ge targets on clean Si substrates. Melting and rapid solidification is then induced by pulsed irradiation (0.54 J/cm2), promoting epitaxial growth.This work has been partially supported by CICYT under project MAT93-0053 and the JNICT-CSIC agreement for traveling finances.Peer reviewe

Memberships and CM Diagrams of the Open Cluster NGC 7243

The results of astrometric and photometric investigations of the open cluster NGC 7243 are presented. Proper motions of 2165 stars with root-mean-square error of 1.1 mas/yr were obtained by means of PDS scanning of astrometric plates covering the time interval of 97 years. A total of 211 cluster members down to V=15.5 mag have been identified. V and B magnitudes have been determined for 2118 and 2110 stars respectively. Estimations of mass (348Mo < M < 522Mo), age (t=2.5x10^8 yr), distance (r=698 pc) and reddening (E(B-V)=0.24) of the cluster NGC 7243 have been made.Comment: 24 pages, 15 figures. Submitted to Astronomy and Astrophysic

Heterogeneous subsidence and paleogeographic elements in an extensional setting revealed through the correlation of a storm deposit unit (Aptian, E Spain)

Durante el Aptiense, en la Subcuenca de Las Parras (NW Cuenca del Maestrazgo) se depositó una unidad siliciclástica en un contexto tectónico extensional. Esta unidad se ha dividido en cuatro secuencias granocrecientes, de las cuales se analiza en detalle la tercera (S3) ya que presenta un alto potencial de correlación lateral. El análisis sedimentológico de la secuencia S3 ha permitido interpretar una evolución vertical de shoreface inferior con procesos de tormenta, a shoreface superior; también ha permitido correlacionar esta secuencia entre dos sectores de la subcuenca que presentan un desarrollo litológico considerablemente diferente. El techo de la secuencia S3 es una superfi cie erosiva menor con valor cronoestratigráfi co y se ha utilizado como datum de correlación para el análisis de la unidad siliciclástica. Las variaciones laterales de facies de la secuencia S3 permiten interpretar la proximidad de un sistema de descarga siliciclástico hacia el sureste, y se propone una zona de intersección de fallas normales, próxima al sector suroriental de la zona estudiada, como un elemento paleoestructural favorable para la entrada de un sistema de drenaje en la cuenca. En el sector suroriental, por encima del datum de correlación, la secuencia S4 presenta un desarrollo muy reducido debido a la ausencia de su parte inferior; esto ha permitido interpretar la presencia de una discontinuidad local intra-S4. Esta discontinuidad local se correlaciona con otra reconocida en el sector noroccidental. Debido a las diferencias de espesor y al grado de desarrollo de la discontinuidad intra-S4 se deduce que la historia de subsidencia de diferentes bloques de la cuenca no es exactamente la misma. Esta discontinuidad intra-S4 podría tener interés regional ya que separa sedimentos dominantemente siliciclásticos de sedimentos carbonatados y podría indicar una modifi cación importante del sistema sedimentario. Para uno de los bloques estudiados, las variaciones espaciales de espesor para cada secuencia podrían representar un desarrollo de la subsidencia alternando periodos con subsidencia diferencial atenuada y periodos con subsidencia diferencial acentuada, que pueden estar relacionados con la dinámica extensional

The development of spontaneous facial responses to others’ emotions in infancy. An EMG study

Viewing facial expressions often evokes facial responses in the observer. These spontaneous facial reactions (SFRs) are believed to play an important role for social interactions. However, their developmental trajectory and the underlying neurocognitive mechanisms are still little understood. In the current study, 4- and 7-month old infants were presented with facial expressions of happiness, anger, and fear. Electromyography (EMG) was used to measure activation in muscles relevant for forming these expressions: zygomaticus major (smiling), corrugator supercilii (frowning), and frontalis (forehead raising). The results indicated no selective activation of the facial muscles for the expressions in 4-month-old infants. For 7-month-old infants, evidence for selective facial reactions was found especially for happy faces (leading to increased zygomaticus major activation) and fearful faces (leading to increased frontalis activation), while angry faces did not show a clear differential response. This suggests that emotional SFRs may be the result of complex neurocognitive mechanisms which lead to partial mimicry but are also likely to be influenced by evaluative processes. Such mechanisms seem to undergo important developments at least until the second half of the first year of life

Eight-month-old infants’ behavioural responses to peers’ emotions as related to the asymmetric frontal cortex activity

Infants are sensitive to and converge emotionally with peers’ distress. It is unclear whether these responses extend to positive affect and whether observing peer emotions motivates infants’ behaviors. This study investigates 8-month-olds’ asymmetric frontal EEG during peers’ cry and laughter, and its relation to approach and withdrawal behaviors. Participants observed videos of infant crying or laughing during two separate sessions. Frontal EEG alpha power was recorded during the first, while infants’ behaviors and emotional expressions were recorded during the second session. Facial and vocal expressions of affect suggest that infants converge emotionally with their peers’ distress, and, to a certain extent, with their happiness. At group level, the crying peer elicited right lateralized frontal activity. However, those infants with reduced right and increased left frontal activity in this situation, were more likely to approach their peer. Overall, 8-month-olds did not show asymmetric frontal activity in response to peer laughter. But, those infants who tended to look longer at their happy peer were more likely to respond with left lateralized frontal activity. The link between variations in left frontal activity and simple approach behaviors indicates the presence of a motivational dimension to infants’ responses to distressed peers

Large Magnetoresistance and Finite-Size Effects in Electrodeposited Single-Crystal Bi Thin Films

Trigonal-axis oriented single-crystal Bi thin films have been made by electrodeposition followed by suitable annealing. Very large magnetoresistance with ratios as much as 1500 at 5 K and 2.9 at 300 K under 5 T, Shubnikov-de Haas oscillations, and finite-size effects have been observed. © 1999 The American Physical Society

Safety Concern between Autologous Fat Graft, Mesenchymal Stem Cell and Osteosarcoma Recurrence

Background: Osteosarcoma is the most common malignant primary bone tumour in young adult treated by neo adjuvant chemotherapy, surgical tumor removal and adjuvant multidrug chemotherapy. For correction of soft tissue defect consecutive to surgery and/or tumor treatment, autologous fat graft has been proposed in plastic and reconstructive surgery. Principal Findings: We report here a case of a late local recurrence of osteosarcoma which occurred 13 years after the initial pathology and 18 months after a lipofilling procedure. Because such recurrence was highly unexpected, we investigated the possible relationship of tumor growth with fat injections and with mesenchymal stem/stromal cell like cells which are largely found in fatty tissue. Results obtained in osteosarcoma pre-clinical models show that fat grafts or progenitor cells promoted tumor growth. Significance: These observations and results raise the question of whether autologous fat grafting is a safe reconstructive procedure in a known post neoplasic context