A variation in the formation of the median nerve: communicating branch between the musculocutaneous and median nerves in man

We encountered variation in the formation of the median nerve in a 66-year-old male cadaver during dissection of the upper extremity of 20 adult cadavers. The dissections were made at the Department of Cellular Biology and Anatomy, Louisiana State University Medical Center. The median nerve was formed by fusion of four branches, three of them coming from the lateral cord and one from the medial cord. The normal radix from the lateral cord followed a very close oblique course over the axillary artery. The first unusual radix to the median nerve had an anastomoses from the musculocutaneous nerve to the median nerve in the proximal part of the left arm. The second unusual radix also came from the musculocutaneous nerve after it had pierced the coracobrachialis muscle and then joined with the median nerve. These kinds of variations are vulnerable to damage in radical neck dissection and other surgical operations of the axilla and upper arm. The communicating branch can be explained on the basis of its embryologic development and also ought to be distinguished from the other nerve variations in the upper extremity. The aim of this paper is to provide additional information for the classification of previously found communications between the musculocutaneous and median nerves

Effect of Lethally Damaged Tumour Cells upon the Growth of Admixed Viable Cells in Diffusion Chambers

IT has been shown that the proliferation of a small viable tumour graft is stimulated by the presence of irreversibly X-ray damaged tumour cells (Revesz, 1958) or viable but genetically incompatible cells (Klein and Klein, 1956). Histological examination (Ringertz, Klein and Revesz, 1959) showed an enhanced granulation tissue formation in and around the implant. The intensity of this reaction was parallel to the stimulating effect of X-ray damaged, genetically incompatible, and heat-killed cells, respectively. This would indicate that the stimulating function may depend on the formation of a proper tumour bed. In addition, a direct " feeder " effect (Puck, Marcus and Cieciura, 1956) may also play a certain role sinice heavily irradiated cells were stimulatory even in the case of freely suspended ascites tumour cells (Revesz, 1955; Scott, 1957; Mazurek and Duplan, 1959). The diffusion chamber technique of Algire, Weaver and Prehn (1954) permits the isolation of the graft from direct contact with host cells. Filter membraines with adequately small pores permit the diffusion of soluble materials but preven

The anastomotic artery connecting the axillary or brachial artery to one of the forearm arteries

A vessel connecting the axillary or brachial artery to one of the forearm arteries was found in a 65 year old male cadaver, during the gross anatomy dissection of the upper extremity of 20 adult cadavers at the Department of Cellular Biology and Anatomy, Louisiana State University Medical Center. The right radial artery originated from the brachial artery nearly at the usual level and was connected to the axillary or brachial artery by a long slender anastomotic artery (vasa aberrantia). The anastomotic artery coursed under the medial side of the biceps muscle between the median and musculocutaneous nerves, and gave off two muscular branches to the biceps muscle. The anastomotic artery coursed between the median and musculocutaneous nerves in the arm, it passed to the forearm under the bicipital aponeurosis and connected the main radial artery on the radial side of the forearm. The anastomotic artery can be explained on the basis of its embryologic development and also ought to be distinguished from the other common arterial variations in the upper extremity

Scalable, Time-Responsive, Digital, Energy-Efficient Molecular Circuits using DNA Strand Displacement

We propose a novel theoretical biomolecular design to implement any Boolean circuit using the mechanism of DNA strand displacement. The design is scalable: all species of DNA strands can in principle be mixed and prepared in a single test tube, rather than requiring separate purification of each species, which is a barrier to large-scale synthesis. The design is time-responsive: the concentration of output species changes in response to the concentration of input species, so that time-varying inputs may be continuously processed. The design is digital: Boolean values of wires in the circuit are represented as high or low concentrations of certain species, and we show how to construct a single-input, single-output signal restoration gate that amplifies the difference between high and low, which can be distributed to each wire in the circuit to overcome signal degradation. This means we can achieve a digital abstraction of the analog values of concentrations. Finally, the design is energy-efficient: if input species are specified ideally (meaning absolutely 0 concentration of unwanted species), then output species converge to their ideal concentrations at steady-state, and the system at steady-state is in (dynamic) equilibrium, meaning that no energy is consumed by irreversible reactions until the input again changes. Drawbacks of our design include the following. If input is provided non-ideally (small positive concentration of unwanted species), then energy must be continually expended to maintain correct output concentrations even at steady-state. In addition, our fuel species - those species that are permanently consumed in irreversible reactions - are not "generic"; each gate in the circuit is powered by its own specific type of fuel species. Hence different circuits must be powered by different types of fuel. Finally, we require input to be given according to the dual-rail convention, so that an input of 0 is specified not only by the absence of a certain species, but by the presence of another. That is, we do not construct a "true NOT gate" that sets its output to high concentration if and only if its input's concentration is low. It remains an open problem to design scalable, time-responsive, digital, energy-efficient molecular circuits that additionally solve one of these problems, or to prove that some subset of their resolutions are mutually incompatible.Comment: version 2: the paper itself is unchanged from version 1, but the arXiv software stripped some asterisk characters out of the abstract whose purpose was to highlight words. These characters have been replaced with underscores in version 2. The arXiv software also removed the second paragraph of the abstract, which has been (attempted to be) re-inserted. Also, although the secondary subject is "Soft Condensed Matter", this classification was chosen by the arXiv moderators after submission, not chosen by the authors. The authors consider this submission to be a theoretical computer science paper

A Macrophage Phenotype for a Constitutive, Class II Antigen-Expressing, Human Dermal Perivascular Dendritic Cell

A previously uncharacterized population of class II antigen-bearing dendritic cells that are intimately associated with the dermal microvasculature was identified in normal human skin using a double-label, indirect immunofluorescence technique. The only other major HLA-DR positive dermal cell type noted in these studies, the dermal microvascular endothelial cell (DMVEC), appeared to express lesser amounts of HLA-DR region gene product than did this dermal perivascular dendritic cell (DPDC). These DPDC were particularly common around small vessels in the superficial vascular plexus of the papillary dermis and were distinct from the mast cell, another cell type normally seen in a similar location. Phenotypic and ultrastructural studies have determined that the DPDC is more closely related to the monocyte/macro-phage lineage than the dendritic cell lineage. The perivascular location and phenotype of this cell distinguishes it from other previously described constitutive dermal cell types such as the classic “histiocyte,” veiled cell, and dendrocyte. The relatively rich expression of all three major HLA-D region gene products by this dermal perivascular dendritic macro-phage would suggest that it could play a significant role in the immunobiology of the dermal microvascular unit

Electron-phonon scattering in quantum point contacts

We study the negative correction to the quantized value $2e^2/h$ of the conductance of a quantum point contact due to the backscattering of electrons by acoustic phonons. The correction shows activated temperature dependence and also gives rise to a zero-bias anomaly in conductance. Our results are in qualitative agreement with recent experiments studying the 0.7 feature in the conductance of quantum point contacts.Comment: 4 pages, no figure

Stub model for dephasing in a quantum dot

As an alternative to Buttiker's dephasing lead model, we examine a dephasing stub. Both models are phenomenological ways to introduce decoherence in chaotic scattering by a quantum dot. The difference is that the dephasing lead opens up the quantum dot by connecting it to an electron reservoir, while the dephasing stub is closed at one end. Voltage fluctuations in the stub take over the dephasing role from the reservoir. Because the quantum dot with dephasing lead is an open system, only expectation values of the current can be forced to vanish at low frequencies, while the outcome of an individual measurement is not so constrained. The quantum dot with dephasing stub, in contrast, remains a closed system with a vanishing low-frequency current at each and every measurement. This difference is a crucial one in the context of quantum algorithms, which are based on the outcome of individual measurements rather than on expectation values. We demonstrate that the dephasing stub model has a parameter range in which the voltage fluctuations are sufficiently strong to suppress quantum interference effects, while still being sufficiently weak that classical current fluctuations can be neglected relative to the nonequilibrium shot noise.Comment: 8 pages with 1 figure; contribution for the special issue of J.Phys.A on "Trends in Quantum Chaotic Scattering

Temperature and magnetic-field dependence of the quantum corrections to the conductance of a network of quantum dots

We calculate the magnetic-field and temperature dependence of all quantum corrections to the ensemble-averaged conductance of a network of quantum dots. We consider the limit that the dimensionless conductance of the network is large, so that the quantum corrections are small in comparison to the leading, classical contribution to the conductance. For a quantum dot network the conductance and its quantum corrections can be expressed solely in terms of the conductances and form factors of the contacts and the capacitances of the quantum dots. In particular, we calculate the temperature dependence of the weak localization correction and show that it is described by an effective dephasing rate proportional to temperature.Comment: 24 pages, 14 figure

Experimental Biological Protocols with Formal Semantics

Both experimental and computational biology is becoming increasingly automated. Laboratory experiments are now performed automatically on high-throughput machinery, while computational models are synthesized or inferred automatically from data. However, integration between automated tasks in the process of biological discovery is still lacking, largely due to incompatible or missing formal representations. While theories are expressed formally as computational models, existing languages for encoding and automating experimental protocols often lack formal semantics. This makes it challenging to extract novel understanding by identifying when theory and experimental evidence disagree due to errors in the models or the protocols used to validate them. To address this, we formalize the syntax of a core protocol language, which provides a unified description for the models of biochemical systems being experimented on, together with the discrete events representing the liquid-handling steps of biological protocols. We present both a deterministic and a stochastic semantics to this language, both defined in terms of hybrid processes. In particular, the stochastic semantics captures uncertainties in equipment tolerances, making it a suitable tool for both experimental and computational biologists. We illustrate how the proposed protocol language can be used for automated verification and synthesis of laboratory experiments on case studies from the fields of chemistry and molecular programming