Chen ranks and resonance

The Chen groups of a group $G$ are the lower central series quotients of the maximal metabelian quotient of $G$. Under certain conditions, we relate the ranks of the Chen groups to the first resonance variety of $G$, a jump locus for the cohomology of $G$. In the case where $G$ is the fundamental group of the complement of a complex hyperplane arrangement, our results positively resolve Suciu's Chen ranks conjecture. We obtain explicit formulas for the Chen ranks of a number of groups of broad interest, including pure Artin groups associated to Coxeter groups, and the group of basis-conjugating automorphisms of a finitely generated free group.Comment: final version, to appear in Advances in Mathematic

Material characterization of structural adhesives in the lap shear mode

A general method for characterizing structual adhesives in the bonded lap shear mode is proposed. Two approaches in the form of semiempirical and theoretical approaches are used. The semiempirical approach includes Ludwik's and Zhurkov's equations to describe respectively, the failure stresses in the constant strain rate and constant stress loading modes with the inclusion of the temperature effects. The theoretical approach is used to describe adhesive shear stress-strain behavior with the use of viscoelastic or nonlinear elastic constitutive equations. Two different model adhesives are used in the single lap shear mode with titanium adherends. These adhesives (one of which was developed at NASA Langley Research Center) are currently considered by NASA for possible aerospace applications. Use of different model adhesives helps in assessment of the generality of the method

Remembering African Labor Migration to the Second World

This open access book is about Mozambicans and Angolans who migrated in state-sponsored schemes to East Germany in the late 1970s and throughout the 1980s. They went to work and to be trained as a vanguard labor force for the intended African industrial revolutions. While they were there, they contributed their labor power to the East German economy. This book draws on more than 260 life history interviews and uncovers complex and contradictory experiences and transnational encounters. What emerges is a series of dualities that exist side by side in the memories of the former migrants: the state and the individual, work and consumption, integration and exclusion, loss and gain, and the past in the past and the past in the present and future. By uncovering these dualities, the book explores the lives of African migrants moving between the Third and Second worlds. Devoted to the memories of worker-trainees, this transnational study comes at a time when historians are uncovering the many varied, complicated, and important connections within the global socialist world

Muon spin rotation and relaxation in the superconducting ferromagnet UCoGe

We report zero-field muon spin rotation and relaxation measurements on the superconducting ferromagnet UCoGe. Weak itinerant ferromagnetic order is detected by a spontaneous muon spin precession frequency below the Curie temperature $T_C = 3$ K. The $\mu^+$ precession frequency persists below the bulk superconducting transition temperature $T_{sc} = 0.5$ K, where it measures a local magnetic field $B_{loc} = 0.015$ T. The amplitude of the $\mu$SR signal provides unambiguous proof for ferromagnetism present in the whole sample volume. We conclude ferromagnetism coexists with superconductivity on the microscopic scale.Comment: 4 pages, 3 figures, accepted for publication in PR

Critical slowing down near the multiferroic phase transition in MnWO4_4

By using broadband dielectric spectroscopy in the radiofrequency and microwave range we studied the magnetoelectric dynamics in the multiferroic chiral antiferromagnet MnWO$_4$. Above the multiferroic phase transition at $T_{N2} \approx 12.6$ K we observe a critical slowing down of the corresponding magnetoelectric fluctuations resembling the soft-mode behavior in canonical ferroelectrics. This electric field driven excitation carries much less spectral weight than ordinary phonon modes. Also the critical slowing down of this mode scales with an exponent larger than one which is expected for magnetic second order phase transition scenarios. Therefore the investigated dynamics have to be interpreted as the softening of an electrically active magnetic excitation, an electromagnon.Comment: 5 pages, 4 figures, appendi

Letter from C. Alwin Schenck to John Muir, 1899 Jan 16.

FOREST DEPARTMENT,BILTMORE ESTATE,C. A. SCHENCK, FORESTER,BILTMORE,N.O.January 16,1899.Mr.John Muir,Martinez,Cal.My Dear Mr. Muir:I am greatly indebted for the copy of The Mountains of California recently sent to me.The book will certainly increase in me the avidity of seeing and studying those mountains personally.I hope good luck will favor me in my endeavors to take a trip out west.I am glad to know that your trip to Florida etc. in the company of Prof. Sargent continued to be pleasant.I would have given a great deal to have been able to accompany you on such an instructive expedition, although,perhaps,there was a little too much botany in it for my digestion.I have recently written to the Secy.of the Sierra Club, not knowing your vital connection with it, relative to the bulletins of the club which I thought were full of forestry interests. I find,however,that they are largely devoted to other purposes and do not think it necessary for that reason to join the sierra Club as I would have done otherwise.Hoping that the year just commenced will have good health in store for you,Very faithfully yours,[illegible]0253

Remembering African Labor Migration to the Second World

This open access book is about Mozambicans and Angolans who migrated in state-sponsored schemes to East Germany in the late 1970s and throughout the 1980s. They went to work and to be trained as a vanguard labor force for the intended African industrial revolutions. While they were there, they contributed their labor power to the East German economy. This book draws on more than 260 life history interviews and uncovers complex and contradictory experiences and transnational encounters. What emerges is a series of dualities that exist side by side in the memories of the former migrants: the state and the individual, work and consumption, integration and exclusion, loss and gain, and the past in the past and the past in the present and future. By uncovering these dualities, the book explores the lives of African migrants moving between the Third and Second worlds. Devoted to the memories of worker-trainees, this transnational study comes at a time when historians are uncovering the many varied, complicated, and important connections within the global socialist world

The perception of the professional self of social workers in private practice

Introduction: The professional self is that part of the social worker that is guided and informed by the values, ethics and principles of the social work profession. It represents a way of conducting oneself as a social worker. The manner or style in which this is done is informed by the personality and creates a certain image which is presented to the public and communicates a message of who this professional person is. The professional self is also that part of the social worker in private practice that has acquired knowledge, skills and experience used in the rendering of the service offered. These skills include, amongst other things, counselling expertise, and organisational and managerial abilities. The professional self aims to be trustworthy, reliable, responsible and accountable. The professional self engages in self-evaluation and personal growth on an ongoing basis. The professional self has the clients’ interests at heart and regards human beings as valuable and worthy of dignity, respect and the right to be self-determining.Department of HE and Training approved lis