The design and construction of the silicon strip microvertex detector (SMD) of the L3 experiment at LEP are described. We present the sensors, readout electronics, data acquisition system, mechanical assembly and support, displacement monitoring systems and radiation monitoring system of the recently installed double-sided, double-layered SMD. This detector utilizes novel and sophisticated techniques for its readout. At the beginning of 1991, the radius of the LEP beam pipe at its four interaction points was reduced from 8.0 cm to 5.5 cm . L3 decided to take advantage of this newly acquired space by installing a silicon microstrip detector (SMD) to upgrade its central tracking capability . The intention was to design, build and install the SMD in a period of just two years so that this new detector would be taking data by 1993 . Consequently, our general design philosophy was to use existing technology as much as possible to guide our choices for such key items as sensor design, readout electronics, data acquisition system, cooling techniques and displacement monitoring systems. The advantages of placing a tracking system with a coordinate resolution of 10 lam close to the beam pipe are well known [1]. For L3, the SMD will significantly improve transverse momentum and impact parameter resolution for studying W-pair production physics at LEP200 (rs 200 GeV), and to provide enhanced b-quark tagging capability to aid a potential Higgs detection in this energy regime . Installation during LEP100 (~s_ mz) facilitates detector debugging due to the large reaction cross section at the Z resonance. 29° SMD two-layer coverage ' ~220 SMD one-layer coverage Fig . 1 . The top view shows the SMD positioned inside the L3 central tracking system . The bottom view shows a transverse view of the SMD's two radial planes.

The L3 central tracking detector has been in operation since the start-up of LEP (Large Electron Positron collider) in 1989. This detector consists of a Time Expansion Chamber (TEC), a layer of Plastic Scintillating Fibers and a Z-chamber. The TEC gives a high spatial resolution and an excellent multi-track reconstruction capability. The fibers are designed to calibrate the drift velocity with high precision. The Z-Chamber provides TEC with accurate information about the z-coordinates of the tracks. A description of the design and the infrastructure of these three detectors, including the readout and data acquisition system, is given. The performance of the detectors during the 1990 and 1991 LEP running periods is presented.

Let L denote the nonscalar complexity in k(x1,…, xn). We prove L(ƒ,∂ƒ/∂x1,…,∂ƒ/∂xn)⩽3L(ƒ). Using this we determine the complexity of single power sums, single elementary symmetric functions, the resultant and the discriminant as root functions, up to order of magnitude. Also we linearly reduce matrix inversion to computing the determinant.

Let ℒ be the first order language of field theory with an additional one place predicate symbol. In [B2] it was shown that the elementary theory T of the class of all pairs of real closed fields, i.e., ℒ-structures ‹K, L›, K a real closed field, L a real closed subfield of K, is undecidable. The aim of this paper is to show that the elementary theory Ts of a nontrivial subclass of containing many naturally occurring pairs of real closed fields is decidable (Theorem 3, §5). This result was announced in [B2]. An explicit axiom system for Ts will be given later. At this point let us just mention that any model of Ts, is elementarily equivalent to a pair of power series fields ‹R0((TA)), R1((TB))› where R0 is the field of real numbers, R1 = R0 or the field of real algebraic numbers, and B ⊆ A are ordered divisible abelian groups. Conversely, all these pairs of power series fields are models of Ts. Theorem 3 together with the undecidability result in [B2] answers some of the questions asked in Macintyre [M]. The proof of Theorem 3 uses the model theoretic techniques for valued fields introduced by Ax and Kochen [A-K] and Ershov [E] (see also [C-K]). The two main ingredients are (i) the completeness of the elementary theory of real closed fields with a distinguished dense proper real closed subfield (due to Robinson [R]), (ii) the decidability of the elementary theory of pairs of ordered divisible abelian groups (proved in §§1-4). I would like to thank Angus Macintyre for fruitful discussions concerning the subject. The valuation theoretic method of classifying theories of pairs of real closed fields is taken from [M].

Der Hemmschuh des Fortschrittes im Gesundheitswesen der dritten Welt liegt im soziokulturellen Bereich. Ein wesentlicher Teil der Therapie der Tropenkrankheiten liegt deshalb in der Gesundheitsanimation. Ihre praktische Durchführung verlangt vor allem eine Aus- und Weiterbildung des bestehenden Gesundheitspersonals und von Bevölkerungsteilen in dieser Disziplin. Leider ist sie noch weitgehend unbekannt und unerforscht. Antworten auf diese Fragen können ganz wesentlich zur Gesamtentwicklung des betreffenden Landes beitragen.

This paper is a contribution to applied categoricity theory. We try to classify isomorphism theorems in a certain area of algebra, by systematic use of the powerful model-theoretic methods of Morley, Shelah, and Ryll-Nardzewski. As far as we know, no results in applied categoricity were published before 1969. Since then the literature has grown quite rapidly. Before stating our main results, we give a survey of the previously known results. The main concepts under study have been K,,-categoricity, N,-categoricity, and w-stability. These concepts apply either to complete theories or to individual structures. Shelah’s notions of superstability and stability are receiving increasing attention, but only in the case of Abelian groups can we give them useful algebraic characterizations at present. In the case of &,-categoricity, satisfactory analyses have been given in the following cases:

Some of the main difficulties encountered in health work in developing countries depend on the sociocultural conditions. Health animatiod until now) of rural health care. Its implementation requires the training and recycling of existing health personnel as well as of parts of the population. It includes the concept of "barefoot doctor", which corresponds well to the prevailing priority health needs. One should note potential difficulties, however, for example in regard to the way the barefoot doctor is to be remunerated (the author discusses some possibilities). It isn't easy either, in practice, to mobilize the community through health education and to obtain its participation in prevention and health promotion measures. The crucial element is to win its confidence. The author describes his practical experiences in Chad in this respect. Health animation stimulates the responsabilization and the development of a prospective outlook in people, and can thus make an important contribution to their overall development efforts. It is necessary to fight factors which slow down such an evolution, among which certain habits as well as obstacles of an administrative nature.

The theory of abelian groups with an additional predicate denoting a subgroup is undecidable.

Every first-order formula in the language ofR-modules (R an associative ring) is equivalent relative to the theory ofR-modules to a boolean combination of positive primitive formulas and ∀∃-sentence.

AbstractIt is shown that the first-order theory ThR(A) of a countable module over an arbitrary countable ring R is ℵ0-categorical if and only if Ai finite, n ∈ ω, κi ≤ ω. Furthermore, ThR(A) is ℵ0-categorical for all R-modules A if and only if R is finite and there exist only finitely many isomorphism classes of indecomposable R-modules.