136 research outputs found
Edematous Ileocecal Valve Mimicking Incomplete Reduction after Intussusception
No full textTeaching Point: An edematous ileocecal valve may mimic a residual intussusception after reduction. Differential diagnosis is important for therapeutic implications
Bifurcations of emergent bursting in a neuronal network
No full textComplex neuronal networks are an important tool to help explain paradoxical phenomena observed in biological recordings. Here we present a general approach to mathematically tackle a complex neuronal network so that we can fully understand the underlying mechanisms. Using a previously developed network model of the milk-ejection reflex in oxytocin cells, we show how we can reduce a complex model with many variables and complex network topologies to a tractable model with two variables, while retaining all key qualitative features of the original model. The approach enables us to uncover how emergent synchronous bursting can arise from a neuronal network which embodies known biological features. Surprisingly, the bursting mechanisms are similar to those found in other systems reported in the literature, and illustrate a generic way to exhibit emergent and multiple time scale oscillations at the membrane potential level and the firing rate level
Een portret van Pieter Aertsen en de Amsterdamse portretschilderkunst 1550-1600
No full textAbstractThe portrait of Symon Marten Dircksz. (1504-1574) preserved in Athens (fig. I, notes 1, 2), was identified on the strength of his coat of arms. The sitter was a staunch Catholic and held high offices in the Amsterdam city government. His portrait, dated 1565, is the earliest specimen of a type that was produced during the last decades of the sixteenth century by the sons of Pieter Aertsen (1507/ 08-1574), Pieter (1540/41-1603) and Aert Pietersz. (1550-1612) (figs. 2, 3, 4, 8, 9). In view of the documented relations between Pieter Aertsen and various prominent Amsterdam citizens and also because of clearly Mannerist features, the portrait may be attributed to the father. It holds a place of its own among Amsterdam portraits of the period and does not relate to any traditional portrait type either in Amsterdam or in Antwerp, where Aertsen had worked until C. 1555. In spite of similarities in the sitters' postures and the ornate background, the portraits attributable to Pieter Pietersz. and Aert Pictersz. (figs. 2, 3, 4, 8, 9) show the style of a younger generation; pictorial space is rendered in a credible way and the figures also appear more three-dimensonal. A late example is the portrait of Hendrick Buyck, signed by Aert Pietersz. and dated 1605 (fig. 8, note 28). The sitter was a successful merchant and joined the Reformed Church, as did most of his brothers and sisters. His portrait contains a wealth of details which may in part point to the traditional idea of transience but also convey information of a more personal nature, as do the texts on the pages of a open cash-book. At his death in 1613 Hendrick Buyck's estate included a small number of paintings, mostly portraits, and one of The Four Evangelists by Pieter Aertsen ('Lange Pier'). This picture may be tentatively identified with one now at Aachen (fig. 10, note 46). A copy of it bears the date 1613 and was in all likelihood made for some member of the Buyck family when the original was inheritcd by the Protestant Hendrick's illegitimate son. The original bears the date 1559 and may well have already been in the possession of Hendrick's grandfather, Cornelis Buyck, who was Pieter Aertsen's neighbour until his death in 1562. POSTSCRIPT HUYBRECHT BEUCKELAER : AN ANTWERP SOLUTION FOR AN AMSTERDAM AND AN ENGLISH PROBLEM The long-standing debate as to whether or not the Monogrammist HB or Hb (figs. 11 and 12) could be identical with Joachim Bcuckclacr, was convincingly settled by Detlev Kreidl (note 27). This author not only analyzed the artist's distinct style but also showed that it was connected with that of Agnolo Bronzino, in whose studio the Monogrammist probably worked. Infrared reflectography subsequently revealed that the Kitchen-maid with a boy and a girl in Brussels (fig. 12), usually thought to be by Pieter Aertsen but attributed by Kreidl to the Monogrammist, bears the signature in full of one H[uybrecht] Beuckelaer, probably a brother of Joachim (note 27). Documents provide scant information on the artist's life. There is evidence of extensive travelling in 1567/68; a letter of 1574 was sent from Bordeaux. His earliest works date from 1563 but only in 1579 did he become a master in the Antwerp guild. This surprisingly late date may be accounted for by the assumption that until then the artist merely (or mainly) assisted other painters. Van Mander relates that Joachim Beuckelaer assisted Antonis Mor for davwages by painting the sitters' attire in their portraits. This piece of information would however seem rather to apply to Huybrecht, who (contrary to Joachim) paid much attention to the rendering of his figures' clothes. An example of his collaboration with Mor may well be the portrait of a nobleman, signed bv Mor and dated 1561, in the Mauritshuis, The Hague (fig. 15, note 64). A number of features in this picture recur in the Brussels Prodigal Son, which bears Huybrecht Beuckelaer's monogram (fig. 11). Huybrecht appears also to have been a portrait painter in his own right. The Style of his Prodigal Son may be recognized in a portrait of Thecla Occo, a member of the powerful Catholic family of that name in Amsterdam (fig. 13, notes 11 and 52). This picture suggests that Huybrecht was familiar with Mor's 1559 portrait of the wife of Jean le Cocq, now in Kassel, where a similar dog (a symbol of conjugal fidelity) lies in its mistress's arm. However, the main inspiration for the style of the Occo portrait comes from portraits Bronzino painted in the mid-1550s. This is borne out by the build of the tall figure with a slender hand dangling from an arm-rest as well as by the narrow shape of the head, enhanced by the strong shadow zone along the right side of the face (cf. fig. 14). From this (and from a similar case to be discussed below) it may be inferred that Huvbrecht visited Bronzino's workshop carly in his career, before working in Mor's studio around 1560. After 1584 there is no further mention of Huybrecht Beuckelaer in Antwerp documents. There is however evidence that he settled in England, probably after the taking of Antwerp by the Spaniards in 1585. A first clue to this effect is supplied by a portrait of Francis Cottington (1578/79-1652), later first Lord Cottington, that was sold at auction in 1922 (fig. 16, note 65). The picture is in many respects very similar to the Prodigal Son though it must, judging by the sitter's age and costume, be dated to the years around 1600, possibly to 1605 when Cottington was appointed secretary to the English ambassador in Spain. The artist's style had remained remarkably constant over the years, and so had his use of Bronzino prototypes. The latter's portrait of the youthful Lodovico Capponi (New York, Frick Collection) must have been in Huybrccht's mind when he designed young Cottington's portrait (fig. 17). There must have been quite a few portraits of distinguished English patrons by Huybrecht Beuckelaer besides the one of Cottington (which is not documented). This is supported by inventories from the years 1583-1590 which mention works by one Hubbert or Hubbard, long considered to have been a Netherlandish artist named Hubert (or Huybrecht - the artist actually used both forms of his name). The works described (notes 72, 73, 75 -77) were mostly portraits. But the earliest mention of his name occurs in connection with A Butcher and a Maid Buying Meat in the Earl of Leicester's collection in 1583. This was obviously a work in the Aertsen-Beuckelaer tradition, such as one might expect from Huybrecht Beuckelaer.
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Subsampling effects in neuronal avalanche distributions recorded in vivo
No full textBackground Many systems in nature are characterized by complex behaviour where large cascades of events, or avalanches, unpredictably alternate with periods of little activity. Snow avalanches are an example. Often the size distribution f(s) of a system's avalanches follows a power law, and the branching parameter sigma, the average number of events triggered by a single preceding event, is unity. A power law for f(s), and sigma=1, are hallmark features of self-organized critical (SOC) systems, and both have been found for neuronal activity in vitro. Therefore, and since SOC systems and neuronal activity both show large variability, long-term stability and memory capabilities, SOC has been proposed to govern neuronal dynamics in vivo. Testing this hypothesis is difficult because neuronal activity is spatially or temporally subsampled, while theories of SOC systems assume full sampling. To close this gap, we investigated how subsampling affects f(s) and sigma by imposing subsampling on three different SOC models. We then compared f(s) and sigma of the subsampled models with those of multielectrode local field potential (LFP) activity recorded in three macaque monkeys performing a short term memory task. Results Neither the LFP nor the subsampled SOC models showed a power law for f(s). Both, f(s) and sigma, depended sensitively on the subsampling geometry and the dynamics of the model. Only one of the SOC models, the Abelian Sandpile Model, exhibited f(s) and sigma similar to those calculated from LFP activity. Conclusions Since subsampling can prevent the observation of the characteristic power law and sigma in SOC systems, misclassifications of critical systems as sub- or supercritical are possible. Nevertheless, the system specific scaling of f(s) and sigma under subsampling conditions may prove useful to select physiologically motivated models of brain function. Models that better reproduce f(s) and sigma calculated from the physiological recordings may be selected over alternatives
Natural theology in St. Thomas's early doctrine of truth
No full textResumen: One of Thomas Aquinas's great legacies is the clarity of his teaching
about the relationships between theology and philosophy, faith and
reason, and grace and nature in general. Of course, that clarity has not
prevented the occasional dispute over the philosophical or theological
status of any number of particular doctrines. And, in fact, a new
controversy has recently begun to form around the status of Thomas's
doctrine of truth.
The dispute turns on whether or not Thomas's doctrine of truth is
fundamentally theological. In his book Medieval Philosophy and the
Transcendentals: The Case of Thomas Aquinas, Jan Aertsen contends
that Thomas's doctrine of the transcendentals is a philosophical
teaching. Inasmuch as Thomas takes truth to be one of the
transcendentals, Aertsen must, of course, (re)construct Thomas's
doctrine of transcendental truth on philosophical grounds—or, as he
describes it, without a "theological foundation'. It is worth noting that
Aertsen's use of the term "theology" here includes natural theology;
thus, in his effort to claim Thomas's doctrine for philosophy, Aertsen
goes so far as to eschew even any natural theological underpinnings. On
the other side of the dispute, in their recent book Truth in Aquinas,
John Milbank and Catherine Pickstock argue that Thomas's doctrine of
truth is "inherently theological"2. It is striking that Pickstock and
Milbank also use the term "theology" in such a way as to include not
only sacra doctrina, but also tenets that most scholars would recognize
as "natural theology"
Restorative Justice and the Potential of 'Exemplarity': In Search of a 'Persuasive' Coherence Within Criminal Justice
No full textA philosophical exploration in the field of RJ is proposed in this chapter. The contribution highlights the difference between criminal justice system which focuses on punishment, coercion, deterrence, incapacitation, enforcement, and negative sanctions, with restorative justice and responsive regulation which focus on rule of conduct, compliance, persuasion, participation, positive sanctions, and reparation. The author argues that restorative justice can show criminal law how to 'work' in a different way and to rethink its aims, drafting an idea in which the law and the justice system have the primary task to protect, not to control or punish. Participation and compliance play a central role, both in designing norms and in responding to their violations. A new theory of criminal law in which norms of conduct are more important than mere sanctions is put forward. Basing her arguments on the philosophical concepts of 'example' and 'exemplarity', as proposed by Alessandro Ferrara, the author argues that restorative justice-oriented norms talk about the experience of injustices with the 'force of example', where 'is' and 'ought' merge. In the frame of restorative justice and responsive regulation, norms address the citizens as examples do, and stimulate their reflective judgment, persuading them, and asking them to comply. In this frame, sanctions too should address citizens as examples do, stimulating their reflective judgment, persuading them, and asking them to comply
[Re] Spike Synchronization And Rate Modulation Differentially Involved In Motor Cortical Function
No full textA reference implementation of Spike synchronization and rate modulation di erentially involved in motor cortical function. Alexa Riehle, Sonja Grün, Markus Diesmann, and Ad Aertsen (1997) Science 278:1950-1953. DOI:10.1126/science.278.5345.19 5
The Role of Fetal Brain Magnetic Resonance Imaging in Current Fetal Medicine
No full textIn open spina bifida we studied the use of MRI for the assessment of the posterior fossa and prevalence of supratentorial anomalies before and after in utero repair. New postprocessing techniques were applied to evaluate fetal brain development in this population compared to controls. In fetuses with congenital diaphragmatic hernia, we evaluated the brain development in comparison to controls. Diffusion weighted imaging was applied to study difference between fetuses with proven first trimester cytomegalovirus infection and controls. Finally, we investigated the value of third trimester fetal brain MRI after treatment for complicated monochorionic diamniotic pregnancies
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