The bicycle: a land survey medium

At the end of the 19th century, the bicycle was a medium of land development, connection, sensing and routing. This article explores these features of the bicycle based on the League of American Wheelmen bulletins that were published between 1880 and 1902. The enquiry shows that the bicycle constitutes a rural geomedium since the first cyclists regarded themselves as land surveyors. Furthermore, the bicycle, as a vehicle that is connected to an individual, links the starting and end points of a route – without stops on the way and without changing vehicles. This continuity of movement is a highly essential property of the medium ‘bicycle’. Being awheel and making the countryside accessible cartographically are therefore closely linked to each other; they take place in one and the same procedure as part of the joint practice of land surveys. During this process, the bicycle proves to be an ideal instrument for the sensing of road surface conditions and therefore functions as a mediator between the road and the cyclist. It also serves as a mediator between urban and rural areas and as a connected device: The bicycle is the condition for cooperation for Bicycle Clubs, which enjoyed enormous popularity at the end of the 19th century. It facilitated the cooperative experiencing and exploring of the land that had yet not been documented cartographically and, in turn, yielded its own new form of representation: navigable maps in the form of route guides.At the end of the 19th century, the bicycle was a medium of land development, connection, sensing and routing. This article explores these features of the bicycle based on the League of American Wheelmen bulletins that were published between 1880 and 1902. The enquiry shows that the bicycle constitutes a rural geomedium since the first cyclists regarded themselves as land surveyors. Furthermore, the bicycle, as a vehicle that is connected to an individual, links the starting and end points of a route – without stops on the way and without changing vehicles. This continuity of movement is a highly essential property of the medium ‘bicycle’. Being awheel and making the countryside accessible cartographically are therefore closely linked to each other; they take place in one and the same procedure as part of the joint practice of land surveys. During this process, the bicycle proves to be an ideal instrument for the sensing of road surface conditions and therefore functions as a mediator between the road and the cyclist. It also serves as a mediator between urban and rural areas and as a connected device: The bicycle is the condition for cooperation for Bicycle Clubs, which enjoyed enormous popularity at the end of the 19th century. It facilitated the cooperative experiencing and exploring of the land that had yet not been documented cartographically and, in turn, yielded its own new form of representation: navigable maps in the form of route guides

Refinement of Copper(II) Azide with 1‐Alkyl‐5H‐tetrazoles: Adaptable Energetic Complexes

A concept for stabilizing highly sensitive and explosive copper(II) azide with 1‐N‐substituted tetrazoles is described. It was possible to stabilize the system by the use of highly endothermic, nitrogen‐rich ligands. The sensitivities of the resulting energetic copper coordination compounds can be tuned further by variation of the alkyl chain of the ligands and by phlegmatization of the complexes with classical additives during the synthesis. It is demonstrated, using the compound based on 1‐methyl‐5H‐tetrazole ([Cu(N3)2(MTZ)], 1) that this class of complexes can be applied as a potential replacement for both lead azide (LA) and lead styphnate (LS). The complex was extensively investigated according to its chemical (elemental analysis, single‐crystal and powder X‐ray diffraction, IR spectroscopy, scanning electron microscopy) and physico‐chemical properties (differential thermal analysis, sensitivities towards impact, friction, and electrostatic discharge) compared to pure copper(II) azide

Novel measurement system for respiratory aerosols and droplets in indoor environments

The SARS-CoV-2 pandemic has created a great demand for a better understanding of the spread of viruses in indoor environments. A novel measurement system consisting of one portable aerosol-emitting mannequin (emitter) and a number of portable aerosol-absorbing mannequins (recipients) was developed that can measure the spread of aerosols and droplets that potentially contain infectious viruses. The emission of the virus from a human is simulated by using tracer particles solved in water. The recipients inhale the aerosols and droplets and quantify the level of solved tracer particles in their artificial lungs simultaneously over time. The mobile system can be arranged in a large variety of spreading scenarios in indoor environments and allows for quantification of the infection probability due to airborne virus spreading. This study shows the accuracy of the new measurement system and its ability to compare aerosol reduction measures such as regular ventilation or the use of a room air purifier

Surface modification of decellularized bovine carotid arteries with human vascular cells significantly reduces their thrombogenicity

Background: Since autologous veins are unavailable when needed in more than 20% of cases in vascular surgery, the production of personalized biological vascular grafts for implantation has become crucial. Surface modification of decellularized xenogeneic grafts with vascular cells to achieve physiological luminal coverage and eventually thromboresistance is an important prerequisite for implantation. However, ex vivo thrombogenicity testing remains a neglected area in the field of tissue engineering of vascular grafts due to a multifold of reasons. Methods: After seeding decellularized bovine carotid arteries with human endothelial progenitor cells and umbilical cord-derived mesenchymal stem cells, luminal endothelial cell coverage (LECC) was correlated with glucose and lactate levels on the cell supernatant. Then a closed loop whole blood perfusion system was designed. Recellularized grafts with a LECC > 50% and decellularized vascular grafts were perfused with human whole blood for 2 h. Hemolysis and complete blood count evaluation was performed on an hourly basis, followed by histological and immunohistochemical analysis. Results: While whole blood perfusion of decellularized grafts significantly reduced platelet counts, platelet depletion from blood resulting from binding to re-endothelialized grafts was insignificant (p = 0.7284). Moreover, macroscopic evaluation revealed thrombus formation only in the lumen of unseeded grafts and histological characterization revealed lack of CD41 positive platelets in recellularized grafts, thus confirming their thromboresistance. Conclusion: In the present study we were able to demonstrate the effect of surface modification of vascular grafts in their thromboresistance in an ex vivo whole blood perfusion system. To our knowledge, this is the first study to expose engineered vascular grafts to human whole blood, recirculating at high flow rates, immediately after seeding

Emergence of qualia from brain activity or from an interaction of proto-consciousness with the brain: which one is the weirder? Available evidence and a research agenda

This contribution to the science of consciousness aims at comparing how two different theories can explain the emergence of different qualia experiences, meta-awareness, meta-cognition, the placebo effect, out-of-body experiences, cognitive therapy and meditation-induced brain changes, etc. The first theory postulates that qualia experiences derive from specific neural patterns, the second one, that qualia experiences derive from the interaction of a proto-consciousness with the brain\u2019s neural activity. From this comparison it will be possible to judge which one seems to better explain the different qualia experiences and to offer a more promising research agenda

Repetitive N-WASP–Binding Elements of the Enterohemorrhagic Escherichia coli Effector EspFU Synergistically Activate Actin Assembly

Enterohemorrhagic Escherichia coli (EHEC) generate F-actin–rich adhesion pedestals by delivering effector proteins into mammalian cells. These effectors include the translocated receptor Tir, along with EspFU, a protein that associates indirectly with Tir and contains multiple peptide repeats that stimulate actin polymerization. In vitro, the EspFU repeat region is capable of binding and activating recombinant derivatives of N-WASP, a host actin nucleation-promoting factor. In spite of the identification of these important bacterial and host factors, the underlying mechanisms of how EHEC so potently exploits the native actin assembly machinery have not been clearly defined. Here we show that Tir and EspFU are sufficient for actin pedestal formation in cultured cells. Experimental clustering of Tir-EspFU fusion proteins indicates that the central role of the cytoplasmic portion of Tir is to promote clustering of the repeat region of EspFU. Whereas clustering of a single EspFU repeat is sufficient to bind N-WASP and generate pedestals on cultured cells, multi-repeat EspFU derivatives promote actin assembly more efficiently. Moreover, the EspFU repeats activate a protein complex containing N-WASP and the actin-binding protein WIP in a synergistic fashion in vitro, further suggesting that the repeats cooperate to stimulate actin polymerization in vivo. One explanation for repeat synergy is that simultaneous engagement of multiple N-WASP molecules can enhance its ability to interact with the actin nucleating Arp2/3 complex. These findings define the minimal set of bacterial effectors required for pedestal formation and the elements within those effectors that contribute to actin assembly via N-WASP-Arp2/3–mediated signaling pathways

Enterohemorrhagic E. coli Requires N-WASP for Efficient Type III Translocation but Not for EspFU-Mediated Actin Pedestal Formation

Upon infection of mammalian cells, enterohemorrhagic E. coli (EHEC) O157:H7 utilizes a type III secretion system to translocate the effectors Tir and EspFU (aka TccP) that trigger the formation of F-actin-rich ‘pedestals’ beneath bound bacteria. EspFU is localized to the plasma membrane by Tir and binds the nucleation-promoting factor N-WASP, which in turn activates the Arp2/3 actin assembly complex. Although N-WASP has been shown to be required for EHEC pedestal formation, the precise steps in the process that it influences have not been determined. We found that N-WASP and actin assembly promote EHEC-mediated translocation of Tir and EspFU into mammalian host cells. When we utilized the related pathogen enteropathogenic E. coli to enhance type III translocation of EHEC Tir and EspFU, we found surprisingly that actin pedestals were generated on N-WASP-deficient cells. Similar to pedestal formation on wild type cells, Tir and EspFU were the only bacterial effectors required for pedestal formation, and the EspFU sequences required to interact with N-WASP were found to also be essential to stimulate this alternate actin assembly pathway. In the absence of N-WASP, the Arp2/3 complex was both recruited to sites of bacterial attachment and required for actin assembly. Our results indicate that actin assembly facilitates type III translocation, and reveal that EspFU, presumably by recruiting an alternate host factor that can signal to the Arp2/3 complex, exhibits remarkable versatility in its strategies for stimulating actin polymerization

Rpb1 Sumoylation in Response to UV Radiation or Transcriptional Impairment in Yeast

Covalent modifications of proteins by ubiquitin and the Small Ubiquitin-like MOdifier (SUMO) have been revealed to be involved in a plethora of cellular processes, including transcription, DNA repair and DNA damage responses. It has been well known that in response to DNA damage that blocks transcription elongation, Rpb1, the largest subunit of RNA polymerase II (Pol II), is ubiquitylated and subsequently degraded in mammalian and yeast cells. However, it is still an enigma regarding how Pol II responds to damaged DNA and conveys signal(s) for DNA damage-related cellular processes. We found that Rpb1 is also sumoylated in yeast cells upon UV radiation or impairment of transcription elongation, and this modification is independent of DNA damage checkpoint activation. Ubc9, an E2 SUMO conjugase, and Siz1, an E3 SUMO ligase, play important roles in Rpb1 sumoylation. K1487, which is located in the acidic linker region between the C-terminal domain and the globular domain of Rpb1, is the major sumoylation site. Rpb1 sumoylation is not affected by its ubiquitylation, and vice versa, indicating that the two processes do not crosstalk. Abolishment of Rpb1 sumoylation at K1487 does not affect transcription elongation or transcription coupled repair (TCR) of UV-induced DNA damage. However, deficiency in TCR enhances UV-induced Rpb1 sumoylation, presumably due to the persistence of transcription-blocking DNA lesions in the transcribed strand of a gene. Remarkably, abolishment of Rpb1 sumoylation at K1487 causes enhanced and prolonged UV-induced phosphorylation of Rad53, especially in TCR-deficient cells, suggesting that the sumoylation plays a role in restraining the DNA damage checkpoint response caused by transcription-blocking lesions. Our results demonstrate a novel covalent modification of Rpb1 in response to UV induced DNA damage or transcriptional impairment, and unravel an important link between the modification and the DNA damage checkpoint response