67 research outputs found
The emotional dimension of friendship: Notes on Aristotleâs account of philia in Rhetoric II 4
This article endeavors to give an
answer to the question whether and to what
extent philia (friendship), as it is treated by Aristotle
in Rhetoric II 4, can be considered a
genuine emotion as, for example, fear and
anger are. Three anomalies are identified in
the definition and the account of philia (and
of the associated verb philein), which suggest
a negative response to the question. However,
these anomalies are analysed and explained
in terms of the specific notes of philia
in order to show that Rhetoric II 4 does allow
for a consideration of friendship as a genuine
emotion
Multiscale Microstructure for Investigation of CellâCell Communication
A multiscale polydimethylsiloxane (PDMS) chip is presented, which provides an array of mesoscale open wells for cell culturing and, as unique feature, an array of microscale 1 ”m deep channels to fluidically connect neighboring wells. As demonstrated with SHâSY5Y cells, the small dimensions of the channels prevent migration of the cell soma but allow physical contacts established by the outgrowth of protoplasmic protrusions between cells in adjacent wells. Another important feature is the chip\u27s mountability on solid substrates, such as glass. This enables the use of substrates previously patterned with biomolecules, as demonstrated by DNAâdirected immobilization of proteins inside the reactor wells. Given the versatile addressability of cells, whether through surfaceâbound or inkjetâbased administration of bioactive substances, it is believed that the reactor could be used for research in cellâcell communication networks, for example, in neurodegenerative diseases such as Alzheimer\u27s disease
Fused Deposition Modeling of Microfluidic Chips in Transparent Polystyrene
Polystyrene (PS) is one of the most commonly used thermoplastic materials worldwide and plays a ubiquitous role in todayâs biomedical and life science industry and research. The main advantage of PS lies in its facile processability, its excellent optical and mechanical properties, as well as its biocompatibility. However, PS is only rarely used in microfluidic prototyping, since the structuring of PS is mainly performed using industrial-scale replication processes. So far, microfluidic chips in PS have not been accessible to rapid prototyping via 3D printing. In this work, we present, for the first time, 3D printing of transparent PS using fused deposition modeling (FDM). We present FDM printing of transparent PS microfluidic channels with dimensions as small as 300 ”m and a high transparency in the region of interest. Furthermore, we demonstrate the fabrication of functional chips such as Tesla-mixer and mixer cascades. Cell culture experiments showed a high cell viability during seven days of culturing, as well as enabling cell adhesion and proliferation. With the aid of this new PS prototyping method, the development of future biomedical microfluidic chips will be significantly accelerated, as it enables using PS from the early academic prototyping all the way to industrial-scale mass replication
Higgs description of two-flavor QCD vacuum
A Higgs description for the QCD vacuum in the limit of two quark flavors is
proposed. Complete ``spontaneous breaking'' of color symmetry is realized by
condensation of an adjoint quark-antiquark and a quark-quark pair. The vacuum
is invariant under isospin symmetry applying color and flavor transformations
simultaneously. All elementary excitations acquire integral charges. The
dressed microscopic quark and gluon degrees of freedom can be identified with
the macroscopic baryon and vector meson degrees of freedom. In addition to the
nucleons we find soliton--type fermions with integer isospin. Their presence
provides an important test accessible to lattice QCD simulations.Comment: 4 page
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