40 research outputs found
Theoretical Behavior of XAI Methods in the Presence of Suppressor Variables
In recent years, the community of 'explainable artificial intelligence' (XAI)
has created a vast body of methods to bridge a perceived gap between model
'complexity' and 'interpretability'. However, a concrete problem to be solved
by XAI methods has not yet been formally stated. As a result, XAI methods are
lacking theoretical and empirical evidence for the 'correctness' of their
explanations, limiting their potential use for quality-control and transparency
purposes. At the same time, Haufe et al. (2014) showed, using simple toy
examples, that even standard interpretations of linear models can be highly
misleading. Specifically, high importance may be attributed to so-called
suppressor variables lacking any statistical relation to the prediction target.
This behavior has been confirmed empirically for a large array of XAI methods
in Wilming et al. (2022). Here, we go one step further by deriving analytical
expressions for the behavior of a variety of popular XAI methods on a simple
two-dimensional binary classification problem involving Gaussian
class-conditional distributions. We show that the majority of the studied
approaches will attribute non-zero importance to a non-class-related suppressor
feature in the presence of correlated noise. This poses important limitations
on the interpretations and conclusions that the outputs of these XAI methods
can afford.Comment: Accepted at ICML 202
Lost to translation: How design factors of the mouse-tracking procedure impact the inference from action to cognition
From an embodiment perspective, action and cognition influence each other constantly. This interaction has been utilized in mouse-tracking studies to infer cognitive states from movements, assuming a continuous manifestation of cognitive processing into movement. However, it is mostly unknown how this manifestation is affected by the variety of possible design choices in mouse-tracking paradigms. Here we studied how three design factors impact the manifestation of cognition into movement in a Simon task with mouse tracking. We varied the response selection (i.e., with or without clicking), the ratio between hand and mouse cursor movement, and the location of the response boxes. The results show that all design factors can blur or even prevent the manifestation of cognition into movement, as reflected by a reduction in movement consistency and action dynamics, as well as by the adoption of unsuitable movement strategies. We conclude that deliberate and careful design choices in mouse-tracking experiments are crucial to ensuring a continuous manifestation of cognition in movement. We discuss the importance of developing a standard practice in the design of mouse-tracking experiments
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Tilt and shift polymorphism in molecular perovskites
Molecular perovskites, i.e. ABX3 coordination polymers with a perovskite structure, are a chemically diverse material platform for studying fundamental and applied materials properties such as barocalorics and improper ferroelectrics. Compared to inorganic perovskites, the use of molecular ions on the A- and X-site of molecular perovskites leads to new geometric and structural degrees of freedom. In this work we introduce the concept of tilt and shift polymorphism, categorising irreversible perovskite-to-perovskite phase transitions in molecular perovskites. As a model example we study the new molecular perovskite series [(nPr)3(CH3)N]M(C2N3)3 with M = Mn2+, Co2+, Ni2+, and nPr = n-propyl, where different polymorphs crystallise in the perovskite structure but with different tilt systems depending on the synthetic conditions. Tilt and shift polymorphism is a direct ramification of the use of molecular building units in molecular perovskites and as such is unknown for inorganic perovskites. Given the role of polymorphism in materials science, medicine and mineralogy, and more generally the relation between physicochemical properties and structure, the concept introduced herein represents an important step in classifying the crystal chemistry of molecular perovskites and in maturing the field
Pre-emptive Allogeneic Hematopoietic Stem Cell Transplantation in Ataxia Telangiectasia
Ataxia telangiectasia (A-T) is a primary immunodeficiency with mutations in the gene encoding the A-T mutated (ATM) protein that interacts with immune, hematopoietic, and endocrine targets resulting in broad multi-systemic clinical manifestations with a devastating outcome. Apart from a progressive neurodegenerative disorder, A-T leads to significantly increased susceptibility to malignancies. It is a matter of discussion whether pre-emptive allogeneic hematopoietic stem cell transplantation (alloHSCT) using a reduced intensity conditioning regimen would be an option to restore immune-competence and prevent malignancy, as shown in animal models, because conventional treatment protocols of malignant diseases using radio- and/or chemotherapy have a high rate of therapy-related morbidity and mortality in these patients. We present the course of the disease, including immune reconstitution and neurological outcome following pre-emptive alloHSCT in a 4-year-old boy with A-T on a 6 year follow-up. Our manuscript provides a proof-of-concept of alloHSCT as an individual pre-emptive treatment strategy from which some A-T patients might benefit
Relativistic, QED and nuclear effects in highly charged ions revealed by resonant electron-ion recombination in storage rings
Dielectronic recombination (DR) of few-electron ions has evolved into a
sensitive spectroscopic tool for highly charged ions. This is due to
technological advances in electron-beam preparation and ion-beam cooling
techniques at heavy-ion storage rings. Recent experiments prove unambiguously
that DR collision spectroscopy has become sensitive to 2nd order QED and to
nuclear effects. This review discusses the most recent developments in
high-resolution spectroscopy of low-energy DR resonances, experimental studies
of KLL DR of very heavy hydrogenlike ions, isotope shift measurements of DR
resonances, and the experimental determination of hyperfine induced decay rates
in divalent ions utilizing DR.Comment: 6 pages, 5 figures, proceedings of the 4th Conference on Elementary
Processes in Atomic Systems, Cluj-Napoca, Romania, June 18-20, 2008, accepted
for publication in Nucl. Instrum. Methods
Interference effects in the photorecombination of argonlike Sc3+ ions: Storage-ring experiment and theory
Absolute total electron-ion recombination rate coefficients of argonlike
Sc3+(3s2 3p6) ions have been measured for relative energies between electrons
and ions ranging from 0 to 45 eV. This energy range comprises all dielectronic
recombination resonances attached to 3p -> 3d and 3p -> 4s excitations. A broad
resonance with an experimental width of 0.89 +- 0.07 eV due to the 3p5 3d2 2F
intermediate state is found at 12.31 +- 0.03 eV with a small experimental
evidence for an asymmetric line shape. From R-Matrix and perturbative
calculations we infer that the asymmetric line shape may not only be due to
quantum mechanical interference between direct and resonant recombination
channels as predicted by Gorczyca et al. [Phys. Rev. A 56, 4742 (1997)], but
may partly also be due to the interaction with an adjacent overlapping DR
resonance of the same symmetry. The overall agreement between theory and
experiment is poor. Differences between our experimental and our theoretical
resonance positions are as large as 1.4 eV. This illustrates the difficulty to
accurately describe the structure of an atomic system with an open 3d-shell
with state-of-the-art theoretical methods. Furthermore, we find that a
relativistic theoretical treatment of the system under study is mandatory since
the existence of experimentally observed strong 3p5 3d2 2D and 3p5 3d 4s 2D
resonances can only be explained when calculations beyond LS-coupling are
carried out.Comment: 11 pages, 7 figures, 3 tables, Phys. Rev. A (in print), see also:
http://www.strz.uni-giessen.de/~k
ATP synthase deficiency due to TMEM70 mutation leads to ultrastructural mitochondrial degeneration and is amenable to treatment.
TMEM70 is involved in the biogenesis of mitochondrial ATP synthase and mutations in the TMEM70 gene impair oxidative phosphorylation. Herein, we report on pathology and treatment of ATP synthase deficiency in four siblings. A consanguineous family of Roma (Gipsy) ethnic origin gave birth to 6 children of which 4 were affected presenting with dysmorphic features, failure to thrive, cardiomyopathy, metabolic crises, and 3-methylglutaconic aciduria as clinical symptoms. Genetic testing revealed a homozygous mutation (c.317-2A>G) in the TMEM70 gene. While light microscopy was unremarkable, ultrastructural investigation of muscle tissue revealed accumulation of swollen degenerated mitochondria with lipid crystalloid inclusions, cristae aggregation, and exocytosis of mitochondrial material. Biochemical analysis of mitochondrial complexes showed an almost complete ATP synthase deficiency. Despite harbouring the same mutation, the clinical outcome in the four siblings was different. Two children died within 60âh after birth; the other two had recurrent life-threatening metabolic crises but were successfully managed with supplementation of anaplerotic amino acids, lipids, and symptomatic treatment during metabolic crisis. In summary, TMEM70 mutations can cause distinct ultrastructural mitochondrial degeneration and almost complete deficiency of ATP synthase but are still amenable to treatment
Rare brain biopsy findings in a first ADEM-like event of pediatric MS: histopathologic, neuroradiologic and clinical features
Pediatric MS tends to present more often with an acute onset and a polysymptomatic form of the disease, possibly with encephalopathy and large tumefactive lesions similar to those observed in some cases of acute disseminated encephalomyelitis (ADEM), which makes it more difficult to differentiate between an explosive and severe onset of MS vs. ADEM. An ADEM-like first demyelinating event can be the first attack of pediatric MS, but international consensus definitions require two or more non-ADEM demyelinating events for diagnosis of MS. In our patient KIDMUS MRI criteria for MS (Mikaeloff et al. J Pediatr 144:246â252, 2004a; Mikaeloff et al. Brain 127:1942â1947, 2004b) were negative at first attack, but Barkhof criteria for lesion dissemination in space in adults (Barkhof et al. 120:2059â2069, 1997), Callen modified MS-criteria and Callen MS-ADEM criteria for children (Callen et al. Neurology 72:961â967, 2009a; Callen et al. Neurology 72:968â973, 2009b) were positive suggesting pediatric MS. As the clinical course was devastating with non-responsiveness upon high-dose immune modulatory therapy and due to the absence of an alternative diagnosis other than demyelinating disease brain biopsy was performed. Brain biopsy studies or autopsy case reports of fulminant pediatric MS patients are extremely rare. Histopathology revealed an inflammatory demyelinating CNS process with confluent demyelination, indicating the likelihood of a relapsing disease course compatible with an acute to subacute demyelinating inflammatory disease. This pattern was corresponding to the early active multiple sclerosis subtype I of Lucchinetti et al. (Ann Neurol 47(6):707â717, 2000)
Current state of cannabis use, policies, and research across sixteen countries : cross-country comparisons and international perspectives
INTRODUCTION : Varying public views on cannabis use across countries may explain the variation in the
prevalence of use, policies, and research in individual countries, and global regulation of cannabis. This
paper aims to describe the current state of cannabis use, policies, and research across sixteen countries.
METHODS : PubMed and Google Scholar were searched for studies published from 2010 to 2020. Searches
were conducted using the relevant country of interest as a search term (e.g., âIranâ), as well as relevant
predefined keywords such as âcannabis,â âmarijuana,â âhashish,â âbhang âdual diagnosis,â âuse,â
âaddiction,â âprevalence,â âco-morbidity,â âsubstance use disorder,â âlegalizationâ or âpolicyâ (in English
and non-English languages). These keywords were used in multiple combinations to create the search
string for studiesâ titles and abstracts. Official websites of respective governments and international
organizations were also searched in English and non-English languages (using countries national
languages) to identify the current state of cannabis use, policies, and research in each of those countries.
RESULTS : The main findings were inconsistent and heterogeneous reporting of cannabis use, variation
in policies (e.g., legalization), and variation in intervention strategies across the countries reviewed.
European countries dominate the cannabis research output indexed on PubMed, in contrast to Asian
countries (Thailand, Malaysia, India, Iran, and Nepal).
CONCLUSIONS : Although global cannabis regulation is ongoing, the existing heterogeneities across
countries in terms of policies and epidemiology can increase the burden of cannabis use disorders
disproportionately and unpredictably. There is an urgent need to develop global strategies to address
these cross-country barriers to improve early detection, prevention, and interventions for cannabis use
and related disorders.The Indian Council of Medical Research.https://www.scielo.br/j/trendsam2023Family Medicin