Postsynaptic Ca2+, but not cumulative depolarization, is necessary for the induction of associative plasticity in Hermissenda

The neuronal modifications that underlie associative memory in Hermissenda have their origins in a synaptic interaction between the visual and vestibular systems, and can be mimicked by contiguous in vitro stimulation of these converging pathways. At the offset of vestibular stimulation (i.e., hair cell activity), the B photoreceptors are briefly released from synaptic inhibition resulting in a slight depolarization (2–4 mV). If contiguous pairings of light-induced depolarization and presynaptic vestibular activity occur in close temporal succession, this depolarization “accumulates” and has been hypothesized to culminate in a sustained rise in intracellular Ca2+ and a resultant Ca(2+)-mediated phosphorylation of K+ channels as well as an associated increase in input resistance. Here we demonstrate that this cumulative depolarization is neither necessary nor sufficient for the biophysical modifications of the B cell membrane indicative of memory formation. Consistent with several recent reports of one-trial learning in Hermissenda, one pairing of light with mechanical stimulation of the vestibular hair cells resulted in a rise in neuronal input resistance across the B cell membrane that was attenuated by a prepairing iontophoretic injection of the Ca2+ chelator EGTA (25 mM), indicating that this potentiation was Ca2+ dependent. However, the use of a single pairing negates the possibility of an accumulation of depolarization across trials. In a subsequent experiment, B photoreceptors underwent a cumulative depolarization, and a coincident rise in input resistance, during multiple pairings of light and hair cell stimulation. However, if the B photoreceptor was voltage clamped at its initial resting potential before and after each pairing, thus eliminating the cumulative depolarization, the rise in resistance not only persisted, but was enhanced. Moreover, if unpaired light presentations were followed by a current-induced depolarization (to mimic cumulative depolarization), no increase in input resistance was detected. To assess directly the effect of a cumulative depolarization on the voltage-dependent Ca2+ current, an analysis of the inward current on the B cell soma membrane was conducted. It was determined that (1) the inward current may undergo a partial inactivation during sustained depolarization, (2) the peak current was depressed during repetitive depolarizations, and (3) the peak current underwent a steady- state inactivation, such that it was reduced when elicited from holding potentials more positive than -60 mV. The analysis of this current suggests that pairings of light and presynaptic activity would reduce voltage-dependent Ca2+ influx when those pairings are conducted at depolarized membrane potentials, such as during cumulative depolarization

Propuesta de un plan de mejora continua para el Centro Regional de Panamá Oeste de la Universidad Tecnológica de Panamá

Investigación realizada en el Centro Regional de Panamá Oeste de la Universidad Tecnológica de Panamá, ciudad de La Chorrera, provincia de Panamá, con el propósito de analizar el desarrollo de las principales actividades de la docencia, investigación y extensión, a fin de contribuir con una propuesta de mejora continua de las acciones que desarrolla este centro universitario, procurando elevar la calidad, pertinencia y eficiencia de los servicios que brinda a la sociedad. La investigación es del tipo descriptiva. Se utilizan diferentes aspectos de la metodología de la investigación, tales como: enfoque metodológico, población y muestra, técnicas e instrumentos de recolección de información y datos, procesamiento y análisis de información y datos. Los instrumentos utilizados para recoger la información fueron: documentos, cuestionarios y entrevistas. El procesamiento de los datos obtenidos por los cuestionarios aplicados a estudiantes y docentes se realizó a través del uso de un programa de hoja de cálculo y estadística, mediante un ordenador personal, presentando los resultados en cuadros y gráficas, con descripciones porcentuales. El Centro Regional de Panamá Oeste requiere implementar un plan de mejoramiento continuo que fortalezca el desarrollo de las actividades de las funciones de docencia, investigación y extensión, incorporando a cada uno de los diferentes estamentos de este centro universitario, como principales protagonistas en los procesos de mejora continua, con la finalidad de elevar la calidad, pertinencia y eficiencia de los servicios que brinda a la sociedad

Pioneering Robotic Liver Surgery in Germany: First Experiences with Liver Malignancies

Background Minimally invasive liver surgery is growing worldwide with obvious benefits for the treated patients. These procedures maybe improved by robotic techniques, which add several innovative features. In Germany, we were the first surgical department implementing robotic assisted minimally invasive liver resections. Material and methods Between June 2013 and March 2015, we performed robotic based minimally invasive liver resections in nine patients with malignant liver disease. Five off these patients suffered from primary and four from secondary liver malignancies. We retrospectively analyzed the perioperative variables of these patients and the oncological follow up. Results Mean age of the patients was 63 years (range 45–71). One patient suffered from intrahepatic cholangiocellular, four from hepatocellular carcinoma, and four patients from colorectal liver metastases. In six patients, left lateral liver resection, in two cases single segment resection, and in one case minimally invasive guided liver ablation were performed. Five patients underwent previous abdominal surgery. Mean operation time was 312 min (range 115–458 min). Mean weight of the liver specimens was 182 g (range 62–260 g) and mean estimated blood loss was 251 ml (range 10–650 ml). The mean tumor size was 4.4 cm (range 3.5–5.5 cm). In all cases, R0 status was confirmed with a mean margin of 0.6 cm (range 0.1–1.5 cm). One patient developed small bowel fistula on postoperative day 5, which could be treated conservatively. No patient died. Mean hospital stay of the patients was 6 days (range 3–10 days). During a mean follow up of 12 months (range 1–21 months), two patients developed tumor recurrence. Conclusion Robotic-based liver surgery is feasible in patients with primary and secondary liver malignancies. To achieve perioperative parameters comparable to open settings, the learning curve must be passed. Minor liver resections are good candidates to start this technique. But the huge benefits of robotic-based liver resections should be expected in extended procedures beyond minor liver resections with the currently available technology

Rates of tectonic and magmatic processes in the North Cascades continental magmatic arc

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2004.Includes bibliographical references.Continental magmatic arcs are among the most dynamic. geologic systems, and documentation of the magmatic, thermal, and tectonic evolution of arcs is essential for understanding the processes of magma generation, ascent and crustal growth. The primary goal of this research is to determine rates of tectonic and magmatic processes in the mid to deep crustal levels of the crystalline core of the Cretaceous North Cascades arc. This region was selected for study because it preserves a -10-40 km depth-section through the arc, which allows an assessment of magmatic and structural processes over a range of crustal levels. The relatively young age of the arc (ca. 100-45 Ma) and the inherent high-precision of U-Pb zircon dates permit absolute uncertainties of <100 ky. Meta-supracrustal rocks of the Cascades core record some of the highest pressures obtained in the North American Cordillera. The timing of deposition and metamorphism of the 9-12 kbar Swakane Gneiss constrain tectonic burial models and the timescales of large crustal displacements within an arc setting. These models involve rapid burial (-7 mm/yr) of a fore- or back-arc basin from ca. 73-68 Ma. Nd isotopic signatures of all meta-clastic terranes of the Cascades core reflect mixing of arc- and craton-derived sediment, and the Swakane Gneiss has the most isotopically-evolved signature of these terranes. Nd isotopic signatures of plutons that intrude the core lack evidence of melting of this isotopically-evolved unit. 40Ar/39Ar and U-Pb thermochronologic data define regional cooling patterns that suggest mid- to Late Cretaceous exhumation coincident with contraction and crustal thickening at the deepest levels of the core, followed by Early Tertiary extension.(cont.) High-precision U-Pb geochronology reveals internal complexities inherent in the construction of an intrusive magmatic system. The Mount Stuart batholith was constructed over a ca. 5.6 Myr time period with four punctuated intervals of magma emplacement, whereas the Tenpeak intrusion was emplaced in a more continuous process over ca. 2.7 Myr time period. U-Pb zircon dates from two elongate intrusions, the Seven- Fingered Jack and Entiat suites, suggest that they were constructed from multiple magmatic sheets that were partially homogenized at the level of emplacement.by Jennifer E. Piontek Matzel.Ph.D

Higher-order associative processing in Hermissenda suggests multiple sites of neuronal modulation.

Two important features of modern accounts of associative learning are (1) the capacity for contextual stimuli to serve as a signal for an unconditioned stimulus (US) and (2) the capacity for a previously conditioned (excitatory) stimulus to block learning about a redundant stimulus when both stimuli serve as a signal for the same US. Here, we examined the process of blocking, thought by some to reflect a cognitive aspect of classical conditioning, and its underlying mechanisms in the marine mollusc Hermissenda. In two behavioral experiments, a context defined by chemosensory stimuli was made excitatory by presenting unsignalled USs (rotation) in that context. The excitatory context subsequently blocked overt learning about a discrete conditioned stimulus (CS; light) paired with the US in that context. In a third experiment, the excitability of the B photoreceptors in the Hermissenda eye, which typically increases following light-rotation pairings, was examined in behaviorally blocked animals, as well as in animals that had acquired a normal CS-US association or animals that had been exposed to the CS and US unpaired. Both the behaviorally blocked and the normal learning groups exhibited increases in neuronal excitability relative to unpaired animals. However, light-induced multiunit activity in pedal nerves was suppressed following normal conditioning but not in blocked or unpaired control animals, suggesting that the expression of blocking is mediated by neuronal modifications not directly reflected in B-cell excitability, possibly within an extensive network of central light-responsive interneurons

Partitioned Waveform Inversion Applied to Eurasia and Northern Africa

This report summarizes the data analysis achieved during Heather Bedle's eleven-week Technical Scholar internship at Lawrence Livermore National Labs during the early summer 2006. The work completed during this internship resulted in constraints on the crustal and upper mantle S-velocity structure in Northern Africa, the Mediterranean, the Middle East, and Europe, through the fitting of regional waveform data. This data extends current raypath coverage and will be included in a joint inversion along with data from surface wave group velocity measurements, S and P teleseismic arrival time data, and receiver function data to create an improved velocity model of the upper mantle in this region. The tectonic structure of the North African/Mediterranean/Europe/Middle Eastern study region is extremely heterogeneous. This region consists of, among others, stable cratons and platforms such as the West Africa Craton, and Baltica in Northern Europe; oceanic subduction zones throughout the Mediterranean Sea where the African and Eurasian plate collide; regions of continental collision as the Arabian Plate moves northward into the Turkish Plate; and rifting in the Red Sea, separating the Arabian and Nubian shields. With such diverse tectonic structures, many of the waveforms were difficult to fit. This is not unexpected as the waveforms are fit using an averaged structure. In many cases the raypaths encounter several tectonic features, complicating the waveform, and making it hard for the software to converge on a 1D average structure. Overall, the quality of the waveform data was average, with roughly 30% of the waveforms being discarded due to excessive noise that interfered with the frequency ranges of interest. An inversion for the 3D S-velocity structure of this region was also performed following the methodology of Partitioned Waveform Inversion (Nolet, 1990; Van der Lee and Nolet, 1997). The addition of the newly fit waveforms drastically extends the range of the model. The model now extends as far east in Africa to cover Chad and Niger, and reaches south to cover Zambia. The model is also stretched eastward to cover the eastern half of India, and northward to cover the southern portion of Scandinavia