The separation problem for regular languages by piecewise testable languages

Separation is a classical problem in mathematics and computer science. It asks whether, given two sets belonging to some class, it is possible to separate them by another set of a smaller class. We present and discuss the separation problem for regular languages. We then give a direct polynomial time algorithm to check whether two given regular languages are separable by a piecewise testable language, that is, whether a $B{\Sigma}1(<)$ sentence can witness that the languages are indeed disjoint. The proof is a reformulation and a refinement of an algebraic argument already given by Almeida and the second author

Discovering The Real World:: the Study and Work Experience Abroad

Historically universities tended to be like monasteries. In fact some started their early history as such. And explicitly or implicitly many Higher Education (HE) institutions still maintain some of the features of these old monasteries. Ideology is an important feature. It might no longer be a belief in God, but certainly the belief in Truth and the duty to seek true knowledge and strive toward a better world have remained, in some form or another, the mission of most universities. The idea also that a university is not a company with an employer and employees, but a community of kindred spirits, living in relative poverty, has stayed with us. And this community feels strongly related to all university communities in the world. Again, universities have kept this essence of internationalism which is typical for monasteries and religious orders. They even kept the notion of hospitality. Universities welcome, for many centuries now, visiting scholars from universities far away as our sisters or brothers. Outside religions and universities this type of international hospitality and professional comradeship is rare

A Characterization for Decidable Separability by Piecewise Testable Languages

The separability problem for word languages of a class $\mathcal{C}$ by languages of a class $\mathcal{S}$ asks, for two given languages $I$ and $E$ from $\mathcal{C}$, whether there exists a language $S$ from $\mathcal{S}$ that includes $I$ and excludes $E$, that is, $I \subseteq S$ and $S\cap E = \emptyset$. In this work, we assume some mild closure properties for $\mathcal{C}$ and study for which such classes separability by a piecewise testable language (PTL) is decidable. We characterize these classes in terms of decidability of (two variants of) an unboundedness problem. From this, we deduce that separability by PTL is decidable for a number of language classes, such as the context-free languages and languages of labeled vector addition systems. Furthermore, it follows that separability by PTL is decidable if and only if one can compute for any language of the class its downward closure wrt. the scattered substring ordering (i.e., if the set of scattered substrings of any language of the class is effectively regular). The obtained decidability results contrast some undecidability results. In fact, for all (non-regular) language classes that we present as examples with decidable separability, it is undecidable whether a given language is a PTL itself. Our characterization involves a result of independent interest, which states that for any kind of languages $I$ and $E$, non-separability by PTL is equivalent to the existence of common patterns in $I$ and $E$

The trans-sialidase from Trypanosoma cruzi induces thrombocytopenia during acute Chagas' disease by reducing the platelet sialic acid contents

Strong thrombocytopenia is observed during acute infection with Trypanosoma cruzi, the parasitic protozoan agent of American trypanosomiasis or Chagas' disease. The parasite sheds trans-sialidase, an enzyme able to mobilize the sialyl residues on cell surfaces, which is distributed in blood and is a virulence factor. Since the sialic acid content on the platelet surface is crucial for determining the half-life of platelets in blood, we examined the possible involvement of the parasite-derived enzyme in thrombocytopenia induction. We found that a single intravenous injection of trans-sialidase into naïve mice reduced the platelet count by 50%, a transient effect that lasted as long as the enzyme remained in the blood. CD43(−/−) mice were affected to a similar extent. When green fluorescent protein-expressing platelets were treated in vitro with trans-sialidase, their sialic acid content was reduced together with their life span, as determined after transfusion into naïve animals. No apparent deleterious effect on the bone marrow was observed. A central role for Kupffer cells in the clearance of trans-sialidase-altered platelets was revealed after phagocyte depletion by administration of clodronate-containing liposomes and splenectomy. Consistent with this, parasite strains known to exhibit more trans-sialidase activity induced heavier thrombocytopenia. Finally, the passive transfer of a trans-sialidase-neutralizing monoclonal antibody to infected animals prevented the clearance of transfused platelets. Results reported here strongly support the hypothesis that the trans-sialidase is the virulence factor that, after depleting the sialic acid content of platelets, induces the accelerated clearance of the platelets that leads to the thrombocytopenia observed during acute Chagas' disease

Genetic Adaptation and Welfare

Beilharz says: The evolutionary processes, if they are not obstructed or misdirected, must lead to such a degree of adaptation that welfare will have to be taken for granted, just as we can do no better than to take for granted the welfare of any wild animal in its natural habitat. From this statement, one might conclude all we have to do is wait, and the animals will eventually adapt to intensive systems. Concerning animals put into new kinds of environments, he states that, if individuals do not have the capacity to adjust phenotypically, adaptation of the population will require a rapid genetic response to prevent dying out of the population. This comment may suggest that one does not have to wait very long for the animals to adapt successfully to intensive systems. He also notes that it is likely that a rapid genetic response is accompanied by much suffering. From this, one might conclude that suffering during such a process is only natural, and is therefore justified. Beilharz writes further that the procedure of adaptation may have to be approached in stages, if the environmental conditions aimed at are radically different from those to which the animals are now adapted. Because he fails to tell us whether intensive husbandry systems belong in this last category of environmental conditions, one might conclude that it is not necessary to adapt animals in stages if they are to be kept under intensive conditions. Therefore, because these statements of Beilharz could be misused to defend the practice of keeping animals under the stress of intensive conditions, under the rationalization that this is part of a long-term rational plan, I want to discuss each of these statements in the following comment

The Terracotta ‘Enthroned Goddess’ of Sicily

Terracotta statuettes were a popular ex-voto in Greek antiquity, varying in size and design. The use of a mold for terracotta figurines was introduced by Greek colonists in the 7th century B.C. to the indigenous people of Sicily. From that moment onwards there was an ongoing interaction between the cultic expressions of these different peoples, which reflected the changed social structures and the production and economic values of votive terracottas. This reciprocal interaction is visible in ..

Depressive and psychotic symptoms in schizophrenia:Focus on networks and treatment

This thesis has two main aims. First, to review and increase knowledge concerning symptom interaction in patients with schizophrenia, with a specific focus on co-occurring depressive symptoms and its neural correlates in major depressive disorder (Part I and II). Second, to review and investigate different treatment aspects and outcomes in schizophrenia (quality of life, depressive symptoms and mortality) (Part III). In sum, both network studies showed the importance of depressive symptoms in the symptom networks of patients with schizophrenia and showed the stability of such a network structure. Although the network approaches has several issues of debate, it is a promising new way of thinking about psychopathology. The network approach is an example of a new conceptualisation of psychopathology as dynamic systems that change over time. Additionally, this view on mental illness facilitates a more transdiagnostic approach, in which emotion regulation should be an important target for future studies. Given the frequent co-occurrence of depressive symptoms in patients with schizophrenia, its centrality, its correlations with suicidality and influence on quality of life, it is highly important to adequately treat co-occurring depressive symptoms and episodes. Systematically following the provided treatment guide to treat depressive symptoms or episodes might be useful. Additionally, meta-analyses showed that schizophrenia patients who do not use antipsychotics have a higher mortality risk compared to patients that use antipsychotics. In a similar way, continuous use of clozapine was related to a lower mortality risk compared to patients using other antipsychotics

Genetic Adaptation and Welfare

Van Rooijen comments on Beilharz’s suggestion (IJSAP 3(2), 117) that it may be possible to adapt domestic animals to existing husbandry systems rather than adapt the systems to the animals. For example, Beilharz cites Tschanz, who has written that the best measurement of adaptation to an environment is reproduction. Van Rooijen provides an example of two bulls – one living freely with a group of cows and one used as a sperm donor, where welfare and reproductive success are not necessarily in harmony. He concludes that the evolutionary fitness and welfare of farm animals do not necessarily coincid