216 research outputs found
Deep Analogical Inference as the Origin of Hypotheses
The ability to generate novel hypotheses is an important problem-solving capacity of humans. This ability is vital for making sense of the complex and unfamiliar world we live in. Often, this capacity is characterized as an inference to the best explanationâselecting the âbestâ explanation from a given set of candidate hypotheses. However, it remains unclear where these candidate hypotheses originate from. In this paper we contribute to computationally explaining these origins by providing the contours of the computational problem solved when humans generate hypotheses. The origin of hypotheses, otherwise known as abduction proper, is hallmarked by seven properties: (1) isotropy, (2) open-endedness, (3) novelty, (4) groundedness, (5) sensibility, (6) psychological realism, and (7) computational tractability. In this paper we provide a computational-level theory of abduction proper that unifies the first six of these properties and lays the groundwork for the seventh property of computational tractability. We conjecture that abduction proper is best seen as a process of deep analogical inference
Intentional Communication: Computationally Easy or Difficult?
Human intentional communication is marked by its flexibility and context sensitivity. Hypothesized brain mechanisms can provide convincing and complete explanations of the human capacity for intentional communication only insofar as they can match the computational power required for displaying that capacity. It is thus of importance for cognitive neuroscience to know how computationally complex intentional communication actually is. Though the subject of considerable debate, the computational complexity of communication remains so far unknown. In this paper we defend the position that the computational complexity of communication is not a constant, as some views of communication seem to hold, but rather a function of situational factors. We present a methodology for studying and characterizing the computational complexity of communication under different situational constraints. We illustrate our methodology for a model of the problems solved by receivers and senders during a communicative exchange. This approach opens the way to a principled identification of putative model parameters that control cognitive processes supporting intentional communication
Ignorance is Bliss: A Complexity Perspective on Adapting Reactive Architectures
Abstract-We study the computational complexity of adapting a reactive architecture to meet task constraints. This computational problem has application in a wide variety of fields, including cognitive and evolutionary robotics and cognitive neuroscience. We show that-even for a rather simple world and a simple task-adapting a reactive architecture to perform a given task in the given world is N P -hard. This result implies that adapting reactive architectures is computationally intractable regardless the nature of the adaptation process (e.g., engineering, development, evolution, learning, etc.) unless very special conditions apply. In order to find such special conditions for tractability, we have performed parameterized complexity analyses. One of our main findings is that architectures with limited sensory and perceptual abilities are efficiently adaptable
Rectal atresia and rectal stenosis:the ARM-Net Consortium experience
Purpose: To assess the number, characteristics, and functional short-, and midterm outcomes of patients with rectal atresia (RA) and stenosis (RS) in the ARM-Net registry. Methods: Patients with RA/RS were retrieved from the ARM-Net registry. Patient characteristics, associated anomalies, surgical approach, and functional bowel outcomes at 1 and 5-year follow-up were assessed. Results: The ARM-Net registry included 2619 patients, of whom 36 (1.3%) had RA/RS. Median age at follow-up was 7.0Â years (IQR 2.3â9.0). Twenty-three patients (63.9%, RA n = 13, RS n = 10) had additional anomalies. PSARP was the most performed reconstructive surgery for both RA (n = 9) and RS (n = 6) patients. At 1-year follow-up, 11/24 patients with known data (45.8%, RA n = 5, RS n = 6) were constipated, of whom 9 required stool softeners and/or laxatives. At 5-year follow-up, 8/9 patients with known data (88.9%, RA n = 4, RS n = 4) were constipated, all requiring laxatives and/or enema. Conclusion: RA and RS are rare types of ARM, representing 1.3% of patients in the ARM-Net registry. Additional anomalies were present in majority of patients. Different surgical approaches were performed as reconstructive treatment, with constipation occurring in 46% and 89% of the patients at 1 and 5-year follow-up. However, accurate evaluation of long-term functional outcomes remains challenging.</p
Maternal risk factors for posterior urethral valves
Introduction: Posterior urethral valves (PUV) is a congenital disorder causing an obstruction of the lower urinary tract that affects approximately 1 in 4,000 male live births. PUV is considered a multifactorial disorder, meaning that both genetic and environmental factors are involved in its development. We investigated maternal risk factors for PUV. Methods: We included 407 PUV patients and 814 controls matched on year of birth from the AGORA data- and biobank and three participating hospitals. Information on potential risk factors (family history of congenital anomalies of the kidney and urinary tract (CAKUT), season of conception, gravidity, subfertility, and conception using assisted reproductive techniques (ART), plus maternal age, body mass index, diabetes, hypertension, smoking, and use of alcohol and folic acid) was derived from maternal questionnaires. After multiple imputation, adjusted odds ratios (aORs) were estimated using conditional logistic regression corrected for minimally sufficient sets of confounders determined using directed acyclic graphs. Results: A positive family history and low maternal age (<25 years) were associated with PUV development [aORs: 3.3 and 1.7 with 95% confidence intervals (95% CI) 1.4â7.7 and 1.0â2.8, respectively], whereas higher maternal age (>35 years) was associated with a lower risk (aOR: 0.7 95% CI: 0.4â1.0). Maternal preexisting hypertension seemed to increase PUV risk (aOR: 2.1 95% CI: 0.9â5.1), while gestational hypertension seemed to decrease this risk (aOR: 0.6 95% CI: 0.3â1.0). Concerning use of ART, the aORs for the different techniques were all above one, but with very wide 95% CIs including one. None of the other factors studied were associated with PUV development. Conclusion: Our study showed that family history of CAKUT, low maternal age, and potentially preexisting hypertension were associated with PUV development, whereas higher maternal age and gestational hypertension seemed to be associated with a lower risk. Maternal age and hypertension as well as the possible role of ART in the development of PUV require further research.</p
Maternal risk associated with the VACTERL association:A case-control study
Background The VACTERL association (VACTERL) includes at least three of these congenital anomalies: vertebral, anal, cardiac, trachea-esophageal, renal, and limb anomalies. Assisted reproductive techniques (ART), pregestational diabetes mellitus, and chronic lower obstructive pulmonary disorders (CLOPD) have been associated with VACTERL. We aimed to replicate these findings and were interested in additional maternal risk factors. Methods A case-control study using self-administered questionnaires was performed including 142 VACTERL cases and 2,135 population-based healthy controls. Multivariable logistic regression analyses were performed to estimate confounder adjusted odds ratios (aOR) and 95% confidence intervals (95%CI). Results Parents who used invasive ART had an increased risk of VACTERL in offspring (aOR 4.4 [95%CI 2.1-8.8]), whereas the increased risk for mothers with CLOPD could not be replicated. None of the case mothers had pregestational diabetes mellitus. Primiparity (1.5 [1.1-2.1]) and maternal pregestational overweight and obesity (1.8 [1.2-2.8] and 1.8 [1.0-3.4]) were associated with VACTERL. Consistent folic acid supplement use during the advised periconceptional period may reduce the risk of VACTERL (0.5 [0.3-1.0]). Maternal smoking resulted in an almost twofold increased risk of VACTERL. Conclusion We identified invasive ART, primiparity, pregestational overweight and obesity, lack of folic acid supplement use, and smoking as risk factors for VACTERL
Inter- and Intraobserver Variation in the Assessment of Preoperative Colostograms in Male Anorectal Malformations: An ARM-Net Consortium Survey
Aim: Male patients with anorectal malformations (ARM) are classified according to
presence and level of the recto-urinary fistula. This is traditionally established by a
preoperative high-pressure distal colostogram that may be variably interpreted by
different surgeons. The aim of this study was to evaluate the inter- and intraobserver
variation in the assessment by pediatric surgeons of preoperative colostograms with
respect to the level of the recto-urinary fistula.
Materials and Methods: Sixteen pediatric surgeons from 14 European centers
belonging to the ARM-Net Consortium twice scored 130 images of distal colostograms
taken in sagittal projection at a median age of 66 days of life (range: 4â1,106 days).
Surgeons were asked to classify the fistula in bulbar, prostatic, bladder-neck, no
fistula, and âunclear anatomyâ example. Their assessments were compared with the
intraoperative findings (kappa) for two scoring rounds with an interval of 6 months
(intraobserver variation). Agreement among the surgeonsâ scores (interobserver variation)
was also calculated using Krippendorffâs alpha. A kappa over 0.75 is considered
excellent, between 0.40 and 0.75 fair to good, and below 0.40 poor. Surgeons were
asked to score the images in âpoorâ and âgoodâ quality and to provide their years of
experience in ARM treatment.
Results: Agreement between the image-based rating of surgeons and the intraoperative
findings ranges from 0.06 to 0.45 (mean 0.31). Interobserver variation is higher
(Krippendorffâs alpha between 0.40 and 0.45). Years of experience in ARM treatment
does not seem to influence the scoring. The mean intraobserver variation between
the two rounds is 0.64. Overall, the quality of the images is considered poor. Images
categorized as having a good quality result in a statistically significant higher kappa
(mean: 0.36 and 0.37 in the first and second round, respectively) than in the group of
bad-quality images (mean: 0.25 and 0.23, respectively).
Conclusions: There is poor agreement among experienced pediatric colorectal
surgeons on preoperative colostograms. Techniques and analyses of images need to be
improved in order to generate a homogeneous series of patients and make comparison
of outcomes reliable
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