Finite 2-groups with exactly one nonmetacyclic maximal subgroup

We determine here the structure of the title groups. All such groups G will be given in terms of generators and relations, and many important subgroups of these groups will be described. Let d(G) be the minimal number of generators of G. We have here d(G) ≤ 3 and if d(G) = 3, then G′ is elementary abelian of order at most 4. Suppose d(G) = 2. Then G′ is abelian of rank ≤ 2 and G/G′ is abelian of type (2, 2^m), m ≥ 2. If G′ has no cyclic subgroup of index 2, then m = 2. If G′ is noncyclic and G/Φ(G ₀) has no normal elementary abelian subgroup of order 8, then G′ has a cyclic subgroup of index 2 and m = 2. But the most important result is that for all such groups (with d(G) = 2) we have G = AB, for suitable cyclic subgroups A and B. Conversely, if G = AB is a finite nonmetacyclic 2-group, where A and B are cyclic, then G has exactly one nonmetacyclic maximal subgroup. Hence, in this paper the nonmetacyclic 2-groups which are products of two cyclic subgroups are completely determined. This solves a long-standing problem studied from 1953 to 1956 by B. Huppert, N. Itô and A. Ohara. Note that if G = AB is a finite p-group, p > 2, where A and B are cyclic, then G is necessarily metacyclic (Huppert [4]). Hence, we have solved here problem Nr. 776 from Berkovich [1].     

The isotope altitude effect reflected in groundwater: a case study from Slovenia

This paper presents the stable isotope data of oxygen (δ¹⁸O) and hydrogen (δ²H) in groundwater from 83 sampling locations in Slovenia and their interpretation. The isotopic composition of water was monitored over 3 years (2009–2011), and each location was sampled twice. New findings on the isotopic composition of sampled groundwater are presented, and the data are also compared to past studies regarding the isotopic composition of precipitation, surface water, and groundwater in Slovenia. This study comprises: (1) the general characteristics of the isotopic composition of oxygen and hydrogen in groundwater in Slovenia, (2) the spatial distribution of oxygen isotope composition (δ¹⁸O) and d-excess in groundwater, (3) the groundwater isotope altitude effect, (4) the correlation between groundwater d-excess and the recharge area altitude of the sampling location, (5) the relation between hydrogen and oxygen isotopes in groundwater in comparison to the global precipitation isotope data, (6) the groundwater isotope effect of distance from the sea, and (7) the estimated relation between the mean temperature of recharge area and δ¹⁸O in groundwater.     

On subgroups of finite <Emphasis Type="Italic">p</Emphasis>-groups

In §2, we prove that if a 2-group G and all its nonabelian maximal sub-groups are two-generator, then G is either metacyclic or minimal non-abelian. In §3, we consider a similar question for p > 2. In §4 the 2-groups all of whose minimal nonabelian subgroups have order 16 and a cyclic subgroup of index 2, are classified. It is proved, in §5, that if G is a nonmetacyclic two-generator 2-group and A, B, C are all its maximal subgroups with d(A) ≤ d(B) ≤ d(C), then d(C) = 3 and either d(A) = d(B) = 3 (this occurs if and only if G/G′ has no cyclic subgroup of index 2) or else d(A) = d(B) = 2. Some information on the last case is obtained in Theorem 5.3.     

Micropump based on electroosmosis of the second kind

A microfluidic pump based on electroosmosis of the second kind was designed and fabricated. Experimental results using DC and AC voltages showed a close to second‐order relationship between flow and voltage, in good agreement with theory. The experimental flow rates were considerably lower than the predicted maximum for the micropumps, which can be attributed to the hydrodynamic resistance of the channel network. This also indicates that higher flow velocities are obtainable for modified pump designs.     

Preliminary phantom measurements for in vivo activation analysis of calcium in the human forearm

Preliminary phantom measurements were carried out for regional determination of calcium in the human forearm. Two paraffine phantoms /large and small/ were activated, either in the free space or surrounded by paraffine plates, by a²⁵²Cf neutron source. Differences between neutron flux densities in positions of the ulna and radius are discussed.