Latest Contributions

Mar 312012
 
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Wolter Seuntjens, Dutch Academy of ‘Pataphysics, Amsterdam, Netherlands

Journal of Unsolved Questions, 2, 2, Open Questions, 4, 2012 (Received 05.02.2012, accepted 27.03.2012, published online 31.03.2012)

In the German language, when referring to an artistic representation of a naked human body, the noun ‘Akt’

is employed. This word was not always used to denote such an artistic representation. The combination of

questions – (1) when, (2) where, (3) by whom, and (4) why was the noun ‘Akt’ first used in this particular

meaning – was the starting point of my quest. This article chronicles the inception of the problem and the

vain attempts to solve it. In short, it is the story of the ‘null result’ of ‘Akt’ research, so far.

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The human lung surfactant proteins A (SP-A) and D (SP-D) share similar binding mechanisms and common ligands on macrophages and dendritic cells

 Latest Contributions, Scientific articles, Vol. 2, Issue 2, July 2012  Comments Off on The human lung surfactant proteins A (SP-A) and D (SP-D) share similar binding mechanisms and common ligands on macrophages and dendritic cells
Feb 182012
 
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Anne Jaekel and Robert B. Sim

MRC Immunochemistry Unit, Department of Biochemistry, University of Oxford, UK

Department of Pharmacology, University of Oxford, UK

Journal of Unsolved Questions, 2, 2, Articles 12-18, 2012 (Received Nov. 21st 2011, accepted Jan. 19th 2012, published online Feb. 18th, 2012)

The lung surfactant collectin proteins SP-A and SP-D have been shown to interact with phagocytic cells, such as macrophages and dendritic cells to facilitate uptake of pathogens and apoptotic cells. However, the mechanism by which the collectins interact with the phagocytes and which surface molecules on the phagocytic cells are involved is not yet clear. In the present study, we demonstrate the interaction of SP-A and SP-D with phagocytic cells including human monocyte-derived macrophages and immature dendritic cells. Results show that both proteins bind in a similar manner to both cell types. A prominent 20-22 kDa doublet band was observed on SDS- PAGE analysis as the major Ca2+ -dependent ligand for SP-A and SP-D on both macrophages and dendritic cells. However, we were unable to identify the proteins involved.

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Dec 282011
 
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Sonja Landertshamer, Clemens Schwarzinger

Johannes Kepler University Linz, Austria

Journal of Unsolved Questions, 2, 1, Articles 5-8, 2012 (Received November 8th, accepted December 3rd, published online December 27th 2011)

2,4,6-triamino-1,3,5-triazine (melamine ) was first prepared in 1834 by Liebig. It has already been used for several decades for the production of melamine-formaldehyde resins and has therefore gained industrial importance. Particularly, during the last years new possibilities for the cross-linking of melamine have been developed to replace harmful formaldehyde. The synthesis of epoxy modified melamine derivatives is one possibility for this purpose. 2-Diallylamino-4,6-bis(dimethylamino)-1,3,5-triazine was chosen as difunctional starting material, whereat solubility in organic solvents is enhanced by the use of the N-alkylated product. Epoxidations of the allyl functionalities were carried out using several common epoxidation agents. Partially, conversion took place forming mainly by-products like substituted hydroxyl amines and hydroxy triazine derivatives. Nevertheless, epoxidation of double bonds took place forming different epoxy containing structures, which may be useful starting materials for further conversions.

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Dependence of E. coli Chemotaxis on CheB Phosphorylation in Silico and in Vivo

 Latest Contributions, Scientific articles, Vol. 2, Issue 1, Jan 2012  Comments Off on Dependence of E. coli Chemotaxis on CheB Phosphorylation in Silico and in Vivo
Dec 032011
 
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Lorenz Adlung

BioQuant Insitute, Im Neuenheimer Feld 267, 69120 Heidelberg, Germany

Zentrum fuer Molekulare Biologie der Universitaet Heidelberg, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany

Journal of Unsolved Questions, 2, 1, Articles 1-4, 2012 (Received October 17th, accepted November 30th, published December 3rd 2011)

The protein CheB is an integral component of sensory adaptation in the chemotaxis system of Escherichia coli. It catalyzes demethylation of the chemoreceptors thereby opposing the effect of ligands on kinase activity. The kinase enhances the activity of the methylesterase via phosphotransfer, thus creating a negative feedback. Although CheB phosphorylation depends on the receptor state, it is not essential for precise adaptation. Therefore, the feedback mechanism is proposed through modeling to compensate for protein fluctuations in the chemotaxis network.

Swarm plate assays revealed that chemotaxis performance in general was even more robust against deviations of single protein concentrations than predicted. However, phosphorylation deficient mutants of CheB still enabled an appropriate chemotaxis response as compared to wild type CheB. Furthermore, when simulations were recoded to include CheB phosphorylation, there was no effect on swarming. Hence both, measured and calculated swarm efficiencies indicate that CheB phosphorylation does not improve robustness of chemotaxis against perturbations in protein levels.

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Keywords: Bacteria, Chemotaxis, Feedback, Robustness

Dec 032011
 
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Christof Troeltzsch, Bliesenrader Weg 5, Born/Darss, Germany

Journal of Unsolved Questions, 2, 1, Open Questions, 3, 2011 (Received November 3rd 2011, accepted November 25th 2011, published December 3rd 2012)

While working on the doctoral thesis about chelates of zirconium and hafnium – cf. [1] for preparation of the ligands and [2] for preparation of the chelates – we made an observation which could not be explained and therefore was only described in the doctoral thesis of Christof Troeltzsch, Leipzig, 1960, in the following way: ….

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Oct 032011
 
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Michael Kurz, Naturkundliche Gesellschaft, Hallein, Austria (e-mail: michael.kurz@gmx.at)

Journal of Unsolved Questions, 2, 1, Open Questions,1-2, 2011 (Received August 25th  2011, accepted September 4th 2011, published September 28th 2011)

If one looks at the stars, it seems astonishing that their velocities as well as those of galaxies are negligible compared to light velocity after almost 14 billion years of gravitation and expansion of the universe. In fact, it seems that there is a very fine tuning between these two cosmic phenomena….

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Jul 232011
 
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Lan Cheng

Institute of Physical Chemistry, Johannes Gutenberg-University Mainz, Staudinger Weg 9, D-55128 Mainz, Germany
Journal of Unsolved Questions, 1, 2, Open Questions, 12-15, 2011 (Received July 18th  2011, accepted July 20th 2011, published July 23rd 2011)

Go (’weiqi’ in Chinese and ’igo’ in Japanese) [1] is an ancient board game originating from China that has been widely played in east Asia. Nowadays Go is being more and more popular throughout the world. In contrast to many other strategic games including chess that have been con- quered by modern computers many years ago, Go remains a formidable challenge to artificial intelligence [2] due to the enormous branching factors of the game tree and, perhaps more importantly, the lack of proper evaluation criteria…

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Keywords: Go, branching factors, artifical intelligence

Jul 232011
 
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Wolter Seuntjens, Karolina Hansen

Dutch Academy of ’Pataphysics, Amsterdam, Netherlands
Friedrich Schiller University, Jena, Germany
Journal of Unsolved Questions, 1, 2, Open Questions, 15-16, 2011 (Received July 19th  2011, accepted July 21st 2011, published July 23rd 2011)

Theory of mind (ToM) is the ability to attribute mental states—beliefs, intents, desires, pretending, knowledge, etc.—to oneself and others, and to understand that others have beliefs, desires, and intentions that are different from one’s own[1]. There is controversy over the question whether animals other than humans have a ToM. The question is important when assessing the status of humans within the animal kingdom. The social tool of faked orgasm seems to be unique to human beings and thus it is a strong test for the demarcation of human versus animal…

[download id=”26″]

Keywords: Theory of Mind, deception, orgasm, bonobo

Jul 182011
 
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Leonie Anna Mueck and Johannes Heymer

Institute of Physical Chemistry, Johannes Gutenberg-University Mainz, Staudinger Weg 9, D-55128 Mainz, Germany
Eberhard Karls University, Tuebingen
Journal of Unsolved Questions, 1, 2, Open Questions, 10-12, 2011 (Received June 25th 2011, accepted July 14th 2011, published July 18th 2011)

“That for which nearly a year had been Vrosnky’s sole and exclusive desire , supplanting all his former desire: That for which Anna had been impossible, dreadful, but all the more betwiching dream of happiness, had come to pass. Pale, with trembling lower jaw, he stood over her, entreating her to be calm, himself not knowing how nor why. … `It’s all over?, she said. `I have nothing but you left. Remember that.?”[1]

Anna Karenina is one of the most prominent and at the same time most tragic adulterers in world literature. What begins as passionate but forbidden love between her and Alexey Vronsky leads to years of ostracism and finally reaches its climax in Anna Karenina’s suicide. In the above scene, where the sexual aspect  of their relationship cannot be overlooked, Anna Karenina already foretells her fate:  “It’s all over”.

The novel is a grand example of  how individuals are torn apart between the social imperative of monogamy and their intrinsic passions. Monogamy is indeed a puzzling social construct, since there seem to be two incompatible souls in us: Our wish for intimacy, consistency, and security on the one hand and our adventurous desires on the other. Some scientists interpret these two souls in a way that suggests that our own evolutionary biology is in conflict with norms and imperatives imposed on us by society and culture. […]

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Keywords: Epidemiology, History of Sexuality

On the Fermionic Shadow Wave Function and novel attempts to solve its sign problem

 Latest Contributions, Scientific articles, Vol. 1, Issue 2, July 2011  Comments Off on On the Fermionic Shadow Wave Function and novel attempts to solve its sign problem
Jul 092011
 
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Francesco Calcavecchia, Francesco Pederiva, and Thomas D. Kuehne

Institute of Physical Chemistry, Johannes Gutenberg-University Mainz, Staudinger Weg 9, D-55128 Mainz, Germany
Dipartimento di Fisica, University of Trento, via Sommerive 14, I-38050 Povo, Trento, Italy
Lawrence Livermore National Laboratory Livermore, California 94550, USA
Center for Computational Sciences, Johannes Gutenberg-University Mainz, Staudinger Weg 9, D-55128 Mainz, Germany

Journal of Unsolved Questions, 1, 2, Articles 13-18, 2011 (Received June 11th, accepted June 30th, published online July 9th 2011)

We present the Fermionic Shadow Wave Function in the context of variational quantum Monte Carlo for disordered systems. Using the example of liquid 3He it is demonstrated that this allows for very accurate calculations, but due to its sign problem only for small systems. For this reason two novel methods are proposed that in principle solve the associated sign problem, but do not allow for realistic simulations yet.

[download id=”22″]

Keywords: Fermionic Shadow Wave Function, Variational Monte Carlo