Lymph Drainage of the Mammary Glands in Female Cats

The mammary gland is a common site of neoplasms in the female cat. All the malignant tumors metastasize to a lesser or a greater extent through the lymphatic system. However, the anatomical knowledge of this system is not sufficiently well known in cats to develop a reasoned model for the extirpation of these glands in case of malignant tumors. A study of the lymph drainage in 50 female cats was done by indirect injection in vivo of India ink inside the mammary parenchyma. After a waiting interval, mammary glands were extracted and the thoracic cavity opened. All the lymph nodes were examined after clearing. The success rate of the colorations of lymph nodes and lymph vessels was 91.8%. Out of the 100 observed mammary chains, the two intermediate mammary glands (T2, A1) may drain caudally to the superficial inguinal lymph center and/or cranially to the axillary lymph center. The T1 gland always drains exclusively cranially and A2 exclusively caudally. The two mammary glands (T1 and A1) often drain towards the sternal cranial lymph nodes, but 100% of the T2 drain towards it. This research assumes that the limit between the two directions of drainage can exist only between glands T2 and A1. The results obtained with the study of the 1st, 2nd, 3rd, and 4th mammary glands permit production of new and more complete data of functional significance that will eventually aid block dissection surgical technique in the removal of malignant tumors in cats. J. Morphol. 000: 000 – 000, 2005. © 2005 Wiley-Liss, Inc. to the inguinal region (Barone, 1996). Generally, the anterior pair of glands is affected and metastases frequently involve the regional lymph nodes and lungs (Hayden and Nielsen, 1971). Earliest surgical excision is the most effective therapy for any mammary tumor. In the cat, few surgical techniques are used in the treatment of mammary tumors (Hayes and Mooney, 1985). Surgical removal of all the glands on the affected side is a common method of treatment. Block dissection surgical techniques involve the removal of the affected mammary glands together with their lymphatic connections with other glands, the lymph nodes toward which these glands drain, and the other glands with which they are connected (Mann, 1984). The application of this technique is very limited in female cats due to the lack of sufficient data on the anatomy of the lymphatic system draining the glands. The few works, when available, are based on a very limited number of animals (Sugimura et al., 1956; Meier, 1989). For these reasons, we decided to investigate the lymphatic drainage and the lymphatic connections between mammary glands in cats, with the aim of developing a reasoned model for the extirpation of these glands in cases of malignant tumors

Toward Fast and Reliable Potential Energy Surfaces for Metallic Pt Clusters by Hierarchical Delta Neural Networks.

Data-driven machine learning force fields (MLFs) are more and more popular in atomistic simulations and exploit machine learning methods to predict energies and forces for unknown structures based on the knowledge learned from an existing reference database. The latter usually comes from density functional theory calculations. One main drawback of MLFs is that physical laws are not incorporated in the machine learning models, and instead, MLFs are designed to be very flexible to simulate complex quantum chemistry potential energy surface (PES). In general, MLFs have poor transferability, and hence, a very large trainset is required to span all the target feature space to get a reliable MLF. This procedure becomes more troublesome when the PES is complicated, with a large number of degrees of freedom, in which building a large database is inevitable and very expensive, especially when accurate but costly exchange-correlation functionals have to be used. In this manuscript, we exploit a high-dimensional neural network potential (HDNNP) on Pt clusters of sizes from 6 to 20 as one example. Our standard level of energy calculation is DFT GGA (PBE) using a plane wave basis set. We introduce an approximate but fast level with the PBE functional and a minimal atomic orbital basis set, and then, a more accurate but expensive level, using a hybrid functional or nonlocal vdW functional and a plane wave basis set, is reliably predicted by learning the difference with HDNNP. The results show that such a differential approach (named ΔHDNNP) can deliver very accurate predictions (error <10 meV/atom) in reference to converged basis set energies as well as more accurate but expensive xc functionals. The overall speedup can be as large as 900 for a 20 atom Pt cluster. More importantly, ΔHDNNP shows much better transferability due to the intrinsic smoothness of the delta potential energy surface, and accordingly, one can use much smaller trainset data to obtain better accuracy than the conventional HDNNP. A multilayer ΔHDNNP is thus proposed to obtain very accurate predictions versus expensive nonlocal vdW functional calculations in which the required trainset is further reduced. The approach can be easily generalized to any other machine learning methods and opens a path to study the structure and dynamics of Pt clusters and nanoparticles

The role of institutions in entrepreneurship: implications for development policy

The last fifty years of development aid have not been rewarded with success. Part of the reason for this failure has been the focus on macro approaches and policies, which did not emphasize the local institutional context faced by eco-nomic agents.In the last decade, the notion of institutions has come to the forefront of policy advice. At the same time however, the role of institutions in economic development remains unclear. As a result, it is being challenged by those who think that institutions are just the fad of the moment.This Policy Primer explains how institutions are vital to the expansion of entrepreneurial activity, which is at the heart of the process of development and economic growth. What is generally missing in countries with lackluster eco-nomic performance is not entrepreneurship as such but the right institutional context for entrepreneurship to take place and to be socially beneficial. What matters for development are the rules that individuals follow and how these rules are defined and enforced.In a successful economy, formal rules are aligned with informal norms and foster entrepreneurial activity by defin-ing and enforcing property rights. The aim of economic policy and social reform must be to re-establish an institutional framework that allows for socially productive entrepreneurial activity to flourish by reducing the cost of engaging in productive activities. This Policy Primer offers three policy implications: define a starting point for reform; build insti-tutional capacity; prepare an environment that favors productive entrepreneurship.In spite of the uncertainty surrounding the path to reform, it is important to keep in mind that the quality of the for-mal and informal institutions is the main determinant of productive entrepreneurship

Economic Capital and Creative Empowerment

We often hear the basic question: “Why some countries are rich and others are poor”. This has been one of the major questions of political economy (and even long before) its more formal or scientific formulation in the late 18th century. Most prominently and especially England, at a time when Western Europe, was experiencing an economic upheaval, disruptions that would totally transform the lives of its inhabitants. Over the last two hundred years, economic development has been rather uneven1. Some countries have witnessed steady growth, year after year, while others stagnated. Some have become rich and then declined. After WWII, the world became divided into three areas: Western countries, the Eastern block, and the South. The first two fought a battle of ideas over a most fundamental question — that of the nature of human societies and the role of freedom. They also fought to impose their respective model over the South — the developing world — and to control its natural resources. After more than half a century of a destructive approach to development, things are now changing and we may have reasons to be optimistic for the next twenty years

Two-probe theory of scanning tunneling microscopy of single molecules: Zn(II)-etioporphyrin on alumina

We explore theoretically the scanning tunneling microscopy of single molecules on substrates using a framework of two local probes. This framework is appropriate for studying electron flow in tip/molecule/substrate systems where a thin insulating layer between the molecule and a conducting substrate transmits electrons non-uniformly and thus confines electron transmission between the molecule and substrate laterally to a nanoscale region significantly smaller in size than the molecule. The tip-molecule coupling and molecule-substrate coupling are treated on the same footing, as local probes to the molecule, with electron flow modelled using the Lippmann-Schwinger Green function scattering technique. STM images are simulated for various positions of the stationary (substrate) probe below a Zn(II)-etioporphyrin I molecule. We find that these images have a strong dependence on the substrate probe position, indicating that electron flow can depend strongly on both tip position and the location of the dominant molecule-substrate coupling. Differences in the STM images are explained in terms of the molecular orbitals that mediate electron flow in each case. Recent experimental results, showing STM topographs of Zn(II)-etioporphyrin I on alumina/NiAl(110) to be strongly dependent on which individual molecule on the substrate is being probed, are explained using this model. A further experimental test of the model is also proposed.Comment: Physical Review B, in pres