Central Subgroup Research Articles

Basic Commutators in Weights Six and Seven as Relators

Charles Sims has asked whether or not the lower central subgroup γ n (F) of a free group F coincides with the normal closure in F of the basic commutators of weight n. This question has a positive answer in weights at most 5, but remains an open question in general. In earlier work with Gaglione and Spellman, it was shown that γ n (F) is the normal closure in F of the basic commutators of weights n through 2n − 4. Here, we specialize to the case where F has rank 2 and show that γ6(F) is the normal closure in F of the basic commutators of weights 6 and 7.

Routine use of self-expanding venous cannulas for cardiopulmonary bypass: benefits and pitfalls in 100 consecutive cases☆

Assess the performance of self-expanding venous cannulas for routine use in open-heart surgery. Prospective study in 100 unselected consecutive patients undergoing open-heart surgery with either remote or central smart venous cannulation. The study focuses on the 76 consecutive adult patients (mean age 59.2+/-17.3 years; 60 males, 16 females) undergoing surgical procedures with total cardiopulmonary bypass for either valve procedures (42/76 patients=55.3%), ascending aorta and arch repair (20/76 patients=26.3%), coronary artery revascularization (13/76 patients=17.1%) or other procedures (11/76 patients=14.5%) with 14/76 patients (18.4%) undergoing redo surgery and 6/76 patients (7.9%) undergoing small access surgery. The mean pump flow achieved by gravity drainage alone accounted for 5.0+/-0.6l/min (=114% of target) in the entire study population (n=76) as compared to the calculated, theoretical pump flow of 4.4+/-0.5l/min (p<0.0001). For the femoral cannulation sub-group (n=35) pump flow achieved by gravity drainage alone accounted for 4.9+/-0.6l/min (=114% of target) as compared to the calculated theoretical pump flow of 4.3+/-0.4l/min (p<0.0001). The corresponding numbers for trans-subclavian cannulation (n=7) are 5.2+/-0.5l/min (111%) for the pump flow achieved by gravity drainage as compared to the theoretical target flow of 4.7+/-0.4l/min. For the central cannulation sub-group (n=34) mean flow achieved by gravity drainage with a self-expanding venous cannula accounted for 5.1+/-0.7l/min (=116% of target) as compared to the calculated theoretical flow of 4.4+/-0.6l/min (p<0.0001). Full or more than target flow was achieved in 97% of the patients studied undergoing CPB with self-expanding venous cannulas and gravity drainage. Remote venous cannulation with self-expanding cannulas provides similar flows as central cannulation. Augmentation of venous return is no longer necessary.

OUTER AUTOMORPHISM GROUPS OF CERTAIN POLYGONAL PRODUCTS OF GROUPS

We show that certain polygonal products of any four groups, amalgamating central subgroups with trivial intersections, have Property E. Using this result, we derive that outer automorphism groups of polygonal products of four polycyclic-by-finite groups, amalgamating central subgroups with trivial intersections, are residually finite.

Periodic Linear Groups with the Weak Chain Conditions on Subgroups of Infinite Central Dimension

Let V be a vector space over a field F. If G ≤ GL(V, F), the central dimension of G is the F-dimension of the vector space V/C V (G). In Dixon et al. (2004) and Kurdachenko and Subbotin (2006), soluble linear groups in which the set ℒ icd(G) of all proper infinite central dimensional subgroups of G satisfies the minimal condition and the maximal condition, respectively, have been described. In this article we study periodic locally radical linear groups, in which the set ℒ icd(G) satisfies one of the weak chain conditions: the weak minimal condition or the weak maximal condition.

Locally nilpotent linear groups with the weak chain conditions on subgroups of infinite central dimension

Let $V$ be a vector space over a field $F$. If $G \leq GL(V,F)$, \emph{the central dimension of $G$} is the $F$-dimension of the vector space $V/C_V(G)$. In [DEK] and [KS], soluble linear groups in which the set $\mathcal{L}_{\operatorname{icd}}(G)$ of all proper infinite central dimensional subgroups of $G$ satisfies the minimal condition and the maximal condition, respectively, have been described. On the other hand, in [MOS], periodic locally radical linear groups in which $\mathcal{L}_{\operatorname{icd}}(G)$ satisfies one of the weak chain conditions (the weak minimal condition or the weak maximal condition) have been characterized. In this paper, we begin the study of the non-periodic case by describing locally nilpotent linear groups in which $\mathcal{L}_{\operatorname{icd}}(G)$ satisfies one of the two weak chain conditions.

COMMUTATOR SUBGROUPS OF FREE NILPOTENT GROUPS

For fixed m, n ≥ 2, we examine the structure of the nth lower central subgroup γn(F) of the free group F of rank m with respect to a certain finite chain F = F(0) &gt; F(1) &gt; ⋯ &gt; F(l-1) &gt; F(l) = {1} of free groups in which F(k) is of finite rank m(k) and is contained in the kth derived subgroup δk(F) of F. The derived subgroups δk(F/γn(F)) of the free nilpotent group F/γn(F) are isomorphic to the quotients F(k)/(F(k) ∩ γn(F)) and admit presentations of the form 〈xk,1,…,xk,m(k): γ(n)(F(k))〉, where γ(n)(F(k)), contained in γn(F), is a certain partial lower central subgroup of F(k). We give a complete description of γn(F) as a staggered product Π1 ≤ k ≤ l-1(γ〈n〉(F(k))*γ[n](F(k)))F(k+1), where γ〈n〉(F(k)) is a free factor of the derived subgroup [F(k),F(k)] of F(k) having countable infinite rank and generated by a certain set of reduced commutators of weight at least n, and γ[n](F(k)) is the subgroup generated by a certain finite set of products of non-reduced ordered commutators of weight at least n. There are some far-reaching consequences.

Relative difference sets fixed by inversion (III)—Cocycle theoretical approach

In this paper, we give a characterization of a group G which contains a semiregular relative difference set R relative to a central subgroup N containing the commutator subgroup [ G , G ] of G such that 1 ∈ R and rRr = R for all r ∈ R . In particular, these relative difference sets are fixed by inversion and inner automorphisms of the group are multipliers. We also present a construction of such relative difference sets.

Una red para promover sistemas de salud basados en la atención primaria de salud en la Región de las Américas

To identify the relational components of an international network of organizations that provide technical and financial assistance to promote the development of health systems based on primary health care in the countries of the Region of the Americas; to analyze the linkages that would allow the collaborating partners of the Pan American Health Organization (PAHO) to work together on health issues; and to determine the basic theoretical elements that can help to develop action strategies that support advocacy efforts by a network. This was a qualitative and quantitative cross-sectional study based on identifying key informants and on analyzing social networks. Ethnographic and relational information from 46 international organizations was collected through a self-administered semistructured questionnaire. From 46 international health cooperation organizations, 29 decision makers from 29 organizations participated (63.0% response rate). The structure and the strength of the network was evaluated in terms of density, closeness, clustering, and centralization. The statistical analysis was done using computer programs that included UCINET, Pajek, and Microsoft Access. We found a structurally centralized theoretical network, whose nodes were clustered into four central subgroups linked by a shared vision. The leadership, influence, and political interests reflected the formal and technical-cooperation linkages, the formal support for health systems based on primary health care, and the flow of resources being more often technical ones than financial ones. The interorganizational relational components and the social-action ties that were identified could help in the development and consolidation of a thematic network for advocacy and for the management of technical and financial assistance that supports primary health care in the Americas. The linkages for joint action that were identified could advance international cooperation in developing health systems based on primary health care, once PAHO formulates clear implementation strategies and takes a leadership position in mobilizing financial resources and in creating informal and interpersonal linkages for action.

Reduced CSF carboxyterminally truncated Aβ peptides in frontotemporal lobe degenerations

Cerebrospinal fluid (CSF) carboxyterminally truncated amyloid-beta (Abeta) peptides, Abeta1-42 and tau protein were evaluated in 30 patients with frontotemporal lobe degenerations (FTLD), 30 Alzheimer's disease (AD) patients and 30 non-demented disease controls (NDC) by Abeta-SDS-PAGE/immunoblot as well as commercial ELISAs for Abeta1-42 and total tau. FTLD displayed a significant drop of Abeta1-37 (p = 2.7 x 10(-4)), Abeta1-38 (p = 4.2 x 10(-5)) and Abeta1-42 (p = 3.3 x 10(-4)). Abeta1-42 was selectively decreased in AD (p = 8.5 x 10(-10)). Decreased Abeta1-38 enabled contrasts of beyond 85% to distinguish FTLD from AD and NDC patients, alone or in combination. Accordingly, low CSF Abeta1-37 and Abeta1-38 represent a biomarker candidate for FTLD and may reflect disease-specific changes of APP metabolism. Further validation should be carried out on dementias other than AD, diagnostically relevant control groups without dementia and without any evident affection of the central nervous system and subgroups of FTLD. Moreover, independent methods of measurement should be applied to CSF Abeta1-38.

Hard X‐Rays and Fluorescent Iron Emission from the Embedded Infrared Cluster in NGC 2071

We present first results of XMM-Newton X-ray observations of the infrared cluster lying near the NGC 2071 reflection nebula in the Orion B region. This cluster is of interest because it is one of the closest regions known to harbor embedded high-mass stars. We report the discovery of hard X-ray emission from the dense central NGC 2071-IR subgroup, which contains at least three high-mass young stellar objects (NGC 2071 IRS 1, IRS 2, and IRS 3). A prominent X-ray source is detected within 1'' of the infrared source IRS 1, which is thought to drive a powerful bipolar molecular outflow. The X-ray spectrum of this source is quite unusual compared to the optically thin plasma spectra normally observed in young stellar objects (YSOs). The spectrum is characterized by a hard broadband continuum plus an exceptionally broad emission line at ≈6.4 keV from neutral or near-neutral iron. The fluorescent Fe line likely originates in cold material near the embedded star (i.e., a disk or envelope) that is irradiated by the hard, heavily absorbed X-ray source.

The Benefactive Construction in South Efate

The benefactive construction in South Efate employs a prepositional phrase in the position immediately preceding the main verb. This position facilitates the expression of an additional participant in a sentence without competing for slots held by other participants (core arguments or adjuncts). Possessive morphology encoding the benefactive has been noted for other Oceanic languages, with distinct word-order marking a final stage of grammaticalization of the benefactive. While South Efate shares features with southern Vanuatu languages, it is shown that a preverbal benefactive is an areal feature of several languages to the north of South Efate, potentially supporting South Efate's position in the Central Vanuatu subgroup.

Persistent central memory phenotype of circulating Fel d 1 peptide/DRB1 ∗0101 tetramer-binding CD4 + T cells

Although substantial evidence suggests that T cells are important in the pathogenesis of atopic dermatitis (AD), little is known of the differentiation status of CD4+ T cells specific for common environmental allergens. To determine the frequency, differentiation phenotype, and function of circulating allergen-specific CD4+ T cells in adult individuals with severe persistent AD and controls. Using tetrameric complexes of an HLA DRB1*0101 restricted epitope from Fel d 1, the major IgE-reactive component of cat dander, we studied ex vivo and cultured T-cell frequency and phenotype in individuals with AD and healthy controls. Cytokine secretion was measured by ex vivo and cultured IFN-gamma, IL-4, and IL-10 enzyme linked immuno-spot analysis. Ex vivo Fel d 1-specific DRB1*0101-restricted CD4+ T cells express high levels of CCR7, CD62L, CD27, and CD28 and proportionately low levels of tissue-specific homing receptors and TH1 and TH2 cytokine production, placing the cells largely within the central memory subgroup. Circulating Fel d 1-specific DRB1*0101-restricted CD4+ T cells maintain central memory capacity, consistent with a potential to contribute to persisting clinical atopic disease. Persisting central memory characteristics of allergen-specific CD4+ T cells in individuals with AD may contribute to chronic disease.

SQUARE INTEGRABLE PROJECTIVE REPRESENTATIONS AND SQUARE INTEGRABLE REPRESENTATIONS MODULO A RELATIVELY CENTRAL SUBGROUP

We introduce the notion of square integrable group representation modulo a relatively central subgroup and, establishing a link with square integrable projective representations, we prove a generalization of a classical theorem of Duflo and Moore. As an example, we apply the results obtained to the Weyl–Heisenberg group.

Physical Therapy for Central Vestibular Dysfunction

Brown KE, Whitney SL, Marchetti GF, Wrisley DM, Furman JM. Physical therapy for central vestibular dysfunction. Objective To determine if vestibular physical therapy (PT) leads to improved functional outcomes in people with central vestibular dysfunction. Design Retrospective case series. Setting Outpatient PT clinic. Participants Forty-eight patients with central vestibular dysfunction met the criteria for inclusion in this retrospective chart review. The 48 patients were divided into various subgroups including central vestibulopathy, cerebellar dysfunction, stroke, mixed central and peripheral vestibulopathy, and posttraumatic central disorders. Intervention Patients were treated with a custom-designed PT program for a mean of 5 visits over an average of 5 months. Main Outcome Measures Patients completed the Activities-Specific Balance Confidence Scale, the Dizziness Handicap Inventory (DHI), the Dynamic Gait Index, the Timed Up & Go test, and the Five Times Sit-to-Stand (FTSTS) Test. Results Significant differences were demonstrated between initial evaluation and discharge in each of the assessment measures for the entire group. Post hoc tests were performed to determine if there was a significant difference in any of the assessment measures by diagnosis. Central vestibular diagnostic subgroup was shown to affect pre- to postintervention differences in the functional and disability measures ( P≤.05). With the exception of the FTSTS, effect sizes of change due to PT intervention were greater in those persons with severe disability at baseline as determined by a DHI score of more than 60. Conclusions Patients with central vestibular dysfunctions improved in both subjective and objective measures of balance after PT intervention. Persons with cerebellar dysfunction improved the least.

Histology of Lymphomas with t(3;14)(q27;q32) Correlates with the Molecular Anatomy of the Translocation.

The t(3;14)(q27;q32) is the most common translocation involving BCL6 in non Hodgkin B-cell lymphoma. Although this translocation has been predominantly associated with diffuse large B-cell lymphoma (DLBCL), recent studies have shown that it can also be found in follicular lymphomas (FL), where it is often associated with a large cell component. To further investigate the relationship that might exist between this translocation and the phenotype of the tumor, we studied 34 B-cell lymphomas with t(3;14)(q27;q32) and diffuse or follicular growth patterns. As the t(3;14)(q27;q32), involving telomeric ends of both chromosomes 3 and 14, is often difficult to detect by conventional cytogenetic, it should be emphasised that only t(3;14) positive FL or DLBCL where the translocation could be validated either by molecular technics (cloning of the breakpoint, amplification of specific IGH-BCL6 fusion transcripts or fluorescence in situ hybridization) were retained in this study. Noteworthy, none of the samples were found to have a t(14;18), indicating that the two most frequent translocations in B-cell NHL, both seen as early transforming events, are usually exclusive. This observation is in agreement with the hypothesis that BCL2 and BCL6 deregulations probably constitute two different lymphomagenesis pathways. Our data also indicate that most t(3;14) positive DLBCL share a CD10−/BCL6+/MUM1+ phenotype (10/16, 62%) and can be classified in the non-germinal centre subgroup (12/16, 75%)%), while a majority of t(3;14) positive FL are CD10− and BCL6+ (10/12, 83%). Moreover, we identified the IGH switch region (S) involved in the translocation for 32 cases, either by cloning the genomic breakpoint (27 cases), and/or by amplifying the IGH-BCL6 fusion transcripts expressed by the tumors (26 cases). For 17/19 (89%) DLBCL or FL with DLBCL, the translocation involved the Sμ, while for 9/13 (70%) FL with no diffuse areas of proliferation the t(3;14) involved a Sγ. These results indicate that the histology of the tumor and the structure of the translocated allele are correlated (p=0.0016), suggesting that the substituted regulatory regions that comes to deregulate BCL6 after a t(3;14) may affect the presentation of the disease.

Multivariate Analysis, Description, and Ecological Interpretation of Weed Vegetation in the Summer Crop Fields of Anhui Province, China

Abstract: Two surveys were conducted to investigate weed vegetation in a 153‐hm2 sampling area of summer crop fields from Anhui Province, China, through visual scoring of the level of weed infestation compared with summer crops on a seven‐class scale. In total, 155 sampling sites were selected in the field based on crops, tillage, rotation systems, geographical regions, and soil types across the province. Data on weed communities and environmental factors were collected and analyzed through principal component analysis (PCA) and canonical correspondence analysis (CCA), and the output was interpreted ecologically. Results showed that the main factors influencing the structure and distribution of weed communities in summer crop fields were the soil submersion period, latitude, and soil type and pH. The CCA indicated a significant relationship between weed dominance and soil submersion duration, latitude, and soil pH. From the result of the PCA and CCA ordination, the 155 sampling sites could be divided into three groups based on geographic and floristic composition, as well as weed abundance. The southern dry land group, which was characterized by a double‐cropping system in the hilly regions of southern and central Anhui Province with a continuous summer crop and an autumn dry land crop, was dominated by Galium aparine Linn. var. tenerum (Gren. et Godr) Robb., Avenafatua L., and Veronicapersica Poir. The northern dry land group, which had the same cropping system as the southern dry land group, was dominated by G. aparine var. tenerum, Galium tricorne Stokes, Descurainia sophia (L.) Schur., and Lithospermum arvense L. in the North Anhui Province, China. These two dry land groups could be combined into one large dry land group, in which the Galium weed vegetation type dominated. The third group was the paddy soil group, which was characterized by a continuous summer crop and double‐ or triple‐cropping systems of rice, and prevailed in the south and central areas of Anhui Province; Alopecurus aequalis Sobol. was the dominant weed in this group. Other main weeds in this group included Malachium aquaticum (L.) Fries, Stellaria alsine Grimm, Alopecurus japonicus Steud., and Lapsana apogonoides Maxim. Thus, the weed community distributions in this group were described as the Alopecurus weed vegetation type. The paddy soil group could be divided into two subgroups, one southern and one central paddy soil subgroup. A strategy for integrated weed management is suggested according to the weed distribution pattern. The present study serves as a good example of how a quantitative research method was used to associate a visual estimate of weed infestation with multivariate analyses, such as PCA and CCA, and how this method can be applied to the study of weed vegetation on arable land.(Managing editor: Ya‐Qin HAN)

THE RESIDUAL FINITENESS OF CERTAIN HNN EXTENSIONS

In this note we give characterizations for certain HNN extensions with central associated subgroups to be residually flnite. We then apply our results to HNN extensions of polycyclic-by-flnite groups.

Cohomology of classifying spaces of central quotients of rank two Kac-Moody groups

Cohomology of classifying spaces of central quotients of rank two Kac-Moody groups

The Efate-Erromango Problem in Vanuatu Subgrouping

While the languages of Erromango clearly belong to the Southern Vanuatu family, and the languages of Efate also clearly belong to the Central Vanuatu subgroup, there are quite a few nonlexical innovations shared by just these languages and none of their close relatives (and, remarkably, apparently very little evidence of lexical sharing). This paper investigates these innovations, and proposes a settlement pattern for central and southern Vanuatu that explains these changes while still recognizing the distinct identity of the two subgroups.

On Conjugacy p-Separability of Free Products of Two Groups with Amalgamation

It is proved that a free product of two finite p-groups with amalgamated central subgroups is a conjugacy p-separable group. With the help of this result, it is proved that a free product with amalgamated subgroups of two finitely generated Abelian groups is a residually finite p-group if and only if it is conjugacy p-separable.