Neuronal projections from the mesencephalic raphe nuclear complex to the suprachiasmatic nucleus and the deep pineal gland of the golden hamster (Mesocricetus auratus)

Neuronal projections from the mesencephalic raphe system to the suprachiasmatic nucleus and the pineal complex were mapped in this study of the golden hamster, by use of the anterograde tracer Phaseolus vulgaris-leucoagglutinin and the retrograde tracer cholera toxin subunit B. From the median raphe nucleus, a rostral projection ascended in the ventral part of the mesencephalon to continue in the medial forebrain bundle of the forebrain. Nerve fibres from this bundle innervated the ventral and medial parts of the suprachiasmatic nucleus. At the level of the interpeduncular nucleus of the mesencephalon, fibres of the ventral bundle bent dorsally to reach the epithalamic area and to continue in the forebrain in a periventricular position. Some of these fibres innervated the dorsal tip of the suprachiasmatic nucleus. The dorsal raphe nucleus was the origin of a nerve fibre bundle, located in the periaqueductal gray of the mesencephalon, innervating the deep pineal gland and pineal stalk. Injection of cholera toxin B into the suprachiasmatic nucleus labelled cells in the median raphe. Combination of the retrograde tracing from the suprachiasmatic nucleus and serotonin transmitter immunohistochemistry showed that some of the cholera toxin B-immunoreactive nerve cells also contained serotonin. Thus, this study of the golden hamster shows a serotonergic projection from the median raphe nucleus to the suprachiasmatic nucleus and a projection from the dorsal raphe nucleus to the deep pineal gland supporting physiological indications of an influence of serotonin on the photoreceptive circadian system of the brain.     

Dry Friction Between Laser-Patterned Surfaces: Role of Alignment, Structural Wavelength and Surface Chemistry

The ability to tune friction by tailoring surface topographies at micron length scales and by changing the relative orientation of crystallites at the atomic scale is well established. Here, we investigate if the two concepts combine, i.e. if the relative orientation of surfaces affects dry friction between laser-textured surfaces. Laser patterning was used on austenitic stainless steel substrates and on tribometer testing balls made of 100Cr6 to create linear periodic arrays with different structural wavelengths or periodicities (5, 9 and 18 ??m). Pairing each substrate with a ball of the same periodicity, the different arrays were subjected to dry sliding tests at 0°/90° relative alignment between the linear patters. We observe that the patterning reduces friction after running-in. The reduction increases with decreasing wavelength and also depends sensitively on the relative alignment and the chemistry of the sliding surfaces. Our results highlight the possibility to create tailored contacting surface geometries leading to tunable frictional properties.     

Synthesis from hyperproperties

We study the reactive synthesis problem for hyperproperties given as formulas of the temporal logic HyperLTL. Hyperproperties generalize trace properties, i.e., sets of traces, to sets of sets of traces. Typical examples are information-flow policies like noninterference, which stipulate that no sensitive data must leak into the public domain. Such properties cannot be expressed in standard linear or branching-time temporal logics like LTL, CTL, or $$\hbox {CTL}^*$$. Furthermore, HyperLTL subsumes many classical extensions of the LTL realizability problem, including realizability under incomplete information, distributed synthesis, and fault-tolerant synthesis. We show that, while the synthesis problem is undecidable for full HyperLTL, it remains decidable for the $$\exists ^*$$, $$\exists ^*\forall ^1$$, and the $${{ linear }}\;\forall ^*$$ fragments. Beyond these fragments, the synthesis problem immediately becomes undecidable. For universal HyperLTL, we present a semi-decision procedure that constructs implementations and counterexamples up to a given bound. We report encouraging experimental results obtained with a prototype implementation on example specifications with hyperproperties like symmetric responses, secrecy, and information flow.     

Analyzing the Spanish strip cipher by combining combinatorial and statistical methods

According to historical reports, many telegrams that date from the Spanish Civil War (1936–1939) still remain undisclosed. It is believed that these telegrams were encrypted with a cryptosystem called the “Spanish Strip Cipher” (SSC).

During this civil war, SSC was the most used cryptographic algorithm. This method corresponds to a homophonic substitution cipher in which a plaintext letter can map to between three and five ciphertext symbols.

By means of cryptanalysis, the authors detect a weakness in the encryption process of the SSC. In this article, they describe how this vulnerability is exploited to efficiently reconstruct a plaintext from a relatively short ciphertext. The attack is based on combinatorial and statistical methods, and it is divided into three phases: homophones-table analysis, letter-frequency analysis, and dictionary search.

The attack was implemented in Java and tested on a laptop with an i7 processor and 4 GB of RAM. The tests were carried out with several real telegrams from the Spanish Civil War. In this article, the authors provide the results of one test that was successfully performed only using the first 201 ciphertext symbols of a Spanish telegram.     

Population Ageing,the Intergenerational Conflict,and Active Ageing Policies – a Multilevel Study of 27 European Countries

In the scientific and the public debate demographic ageing is sometimes perceived as an unstoppable “grey tide” which will inevitably lead to a conflict between the old and young generation. In this paper we empirically evaluate whether we find any evidence for an intergenerational conflict in Europe and which factors might influence its severity. In particular, we answer the following questions. (1) Is there a conflict between the interests of the younger and the older generation? (2) Does the strength of the conflict increase with population ageing? And finally, (3) can a policy of Active Ageing, i.e. better integrating older generations into society, moderate the conflict? We answer these questions in a comparative study of 27 European countries using data from the Eurobarometer 2009. Our results show a moderate conflict between generations. Compared to spending preferences of the younger generation, older people are more likely to support increased spending for old age at the expense of educational spending. Contrary to expectation, generational conflict does not increase with population ageing. Linking country differences in the strength of the generational conflict to the degree of population ageing with multilevel regression techniques we do not find any evidence that the conflict is increasing In a final step of our analysis we evaluate the potential of generational policies - measured with the Active Aging Index - to mitigate the generational conflict. Intergenerational conflict is weaker when older people actively participate in the political life and are visible in society, suggesting Active Aging policies as a means to mitigate intergenerational conflict     

Decision trees for hierarchical multi-label classification

Hierarchical multi-label classification (HMC) is a variant of classification where instances may belong to multiple classes at the same time and these classes are organized in a hierarchy. This article presents several approaches to the induction of decision trees for HMC, as well as an empirical study of their use in functional genomics. We compare learning a single HMC tree (which makes predictions for all classes together) to two approaches that learn a set of regular classification trees (one for each class). The first approach defines an independent single-label classification task for each class (SC). Obviously, the hierarchy introduces dependencies between the classes. While they are ignored by the first approach, they are exploited by the second approach, named hierarchical single-label classification (HSC). Depending on the application at hand, the hierarchy of classes can be such that each class has at most one parent (tree structure) or such that classes may have multiple parents (DAG structure). The latter case has not been considered before and we show how the HMC and HSC approaches can be modified to support this setting. We compare the three approaches on 24 yeast data sets using as classification schemes MIPS’s FunCat (tree structure) and the Gene Ontology (DAG structure). We show that HMC trees outperform HSC and SC trees along three dimensions: predictive accuracy, model size, and induction time. We conclude that HMC trees should definitely be considered in HMC tasks where interpretable models are desired.