bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of PFA quality and conditioning in minimising alkali–silica reaction in concrete
Authors: McCarthy M. J. , Dhir R. K. , Halliday J. E. , Wibowo A.
Published: January 2006

This paper describes the work of a study carried out to assess the effect of pulverised full ash (PFA) quality (including conditioned (moistened) PFA) on its ability to minimise the risk of alkali–silica reaction (ASR) in concrete and thereby, whether the wider range of materials covered in BS 3892-1, BS 3892-2 and BS EN 450 can be used in this role. A total of 11 PFAs (within and between sources) and three types of aggregate combination, covering materials used in the UK, were examined. Two series of tests were carried out, which used concrete mixes proportioned to (a) the BS 812-123 standard method (alkali content 7·0 kg/m3) and (b) the BRE method (alkali content from 3·6 to 6·0 kg/m3), using the BS 812-123 test procedure (38°C, above water). The results obtained over three years, established that the physical and chemical properties of PFA (fineness and alkali content (Na2Oeq)) had only a minor influence on its ability to minimise ASR risk. Conditioning of PFA and its loss on ignition appeared to have no effect. Overall, the results suggest that PFA to BS 3892-2 and to BS EN 450, may be considered to be equally as effective as BS 3892-1 PFA in minimising ASR in concrete, containing potentially reactive aggregates available in the UK. The outcomes of this and other work have been considered by the ASI concrete committee and this has led to a change in BS 8500, which now permits the use of BS EN 450 PFA.
Target Region Amplification Polymorphism (TRAP) for Assessing Genetic Diversity in Sugarcane Germplasm Collections
Authors: Alwala S. , Suman A. , Arro J. A. , Veremis J. C. , Kimbeng C. A.
Published: January 2006

Target region amplification polymorphism (TRAP) is a fairly new PCR‐based molecular marker technique which uses gene‐based information for primer design. The objective of this study was to evaluate the utility of TRAP markers for assessing genetic diversity and interrelationships in sugarcane germplasm collections. Thirty genotypes from the genera Saccharum, Miscanthus, and Erianthus were used in the study. Among the genus Saccharum were the species, S. officinarum L., S. barberi Jesw., S. sinense Roxb, S. spontaneum L, S. robustum Brandes and Jeswiet ex Grassl, cultivars, cultivar‐derived mutants and interspecific hybrids between S. officinarum and S. spontaneum Six fixed primers, designed from sucrose‐ and cold tolerance‐related EST (expressed sequence tags) sequences, paired with three arbitrary primers, were used to characterize the germplasm. Both the cluster and principal coordinate (PCoA) analyses placed the Erianthus spp. and Miscanthus spp. genotypes distinctly from each other and from the Saccharum species, thus, supporting their taxonomic classification as separate genera. Genotypes of the low sucrose and cold tolerant species, S. spontaneum, formed one distinct group, while the rest of the Saccharum species formed one interrelated cluster with no distinct subgroups. Sequence analysis of TRAP bands derived from a S. spontaneum genotype revealed homology with known gene sequences from other grass species including Sorghum A BLASTn search using the homologous sequences from Sorghum matched with the S. officinarum GenBank accession from which the fixed TRAP primer was designed. These results ratify TRAP as a potentially useful marker technique for genetic diversity studies in sugarcane.
High‐Throughput DNA Extraction and Allele Specific PCR Primers Enables Efficient Screening for Mutant (gsf) and Wild‐Type (GSF) Alleles in Eastern Gamagrass
Authors: Goldman Jason J.
Published: January 2006

Eastern gamagrass [Tripsacum dactyloides (L.) L.], is a perennial warm‐season bunchgrass with high forage potential if properly managed. Low seed production is one factor that has limited wide spread use of this native grass. A recessive gynomonoecious sex form (GSF) mutation previously found in a wild population has the potential to increase seed production, although it may also be linked to other deleterious traits. Allele specific primers were designed to detect the wild‐type (GSF) and mutant (gsf) allele. Primers were successful at confirming the genotype of an assortment of plants tested using template DNA from a high‐throughput extraction protocol. A tissue‐pooling strategy enabled detection of the mutant allele when present in a predominantly wild‐type background. The low cost, lack of toxic waste, and speed of the DNA extraction protocol and the ability to efficiently genotype a large number of individuals makes this a practical tool in a breeding program working with the GSF trait.
Lrrk2 and Lewy body disease
Authors: Ross Owen A. , Toft Mathias , Whittle Andrew J. , Johnson Joseph L. , Papapetropoulos Spiridon , Mash Deborah C. , Litvan Irene , Gordon Mark F. , Wszolek Zbigniew K. , Farrer Matthew J. , Dickson Dennis W.
Published: January 2006

Objective

The Lrrk2 kinase domain G2019S substitution is the most common genetic basis of familial and sporadic parkinsonism. Patients harboring the G2019S substitution usually present with clinical Parkinson's disease.

Methods

Herein, we report that the most common neuropathology of G2019S‐associated Parkinson's disease is Lewy body disease.

Results

Lrrk2 G2019S was observed in approximately 2% (n = 8) of our Parkinson's disease/Lewy body disease cases (n = 405). The mutation was also found in one control subject and one Alzheimer's disease patient, reflecting reduced penetrance.

Interpretation

Therapeutic strategies targeted at modulating Lrrk2 kinase activity may be important to treat patients with genetically defined familial or typical sporadic Parkinson's disease. Ann Neurol 2006;59:388–393
Docosahexaenoic acid reduces levodopa‐induced dyskinesias in 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine monkeys
Authors: Samadi Pershia , Grégoire Laurent , Rouillard Claude , Bédard Paul J. , Di Paolo Thérèse , Lévesque Daniel
Published: January 2006

Objective

The objective of the present study was to investigate the effect of docosahexaenoic acid (DHA), a polyunsaturated fatty acid (omega‐3), on levodopa‐induced dyskinesias (LIDs) in parkinsonian 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP)–treated monkeys.

Methods

We explored the effect of DHA in two paradigms. First, a group of MPTP monkeys was primed with levodopa for several months before introducing DHA. A second group of MPTP monkeys (de novo) was exposed to DHA before levodopa therapy.

Results

DHA administration reduced LIDs in both paradigms without alteration of the anti‐parkinsonian effect of levodopa indicating that DHA can reduce the severity or delay the development of LIDs in a nonhuman primate model of Parkinson's disease.

Interpretation

These results suggest that DHA can reduce the severity or delay the develoment of LIDs in a nonhuman primate model of Parkinson's disease. DHA may represent a new approach to improve the quality of life of Parkinson's disease patients. Ann Neurol 2006;59:282–288
Sarcolemmal reorganization in facioscapulohumeral muscular dystrophy
Authors: Reed Patrick , Porter Neil C. , Strong John , Pumplin David W. , Corse Andrea M. , Luther Paul W. , Flanigan Kevin M. , Bloch Robert J.
Published: January 2006

Objective

We examined the sarcolemma of skeletal muscle from patients with facioscapulohumeral muscular dystrophy (FSHD1A) to learn if, as in other murine and human muscular dystrophies, its organization and relationship to nearby contractile structures are altered.

Methods

Unfixed biopsies of control and FSHD deltoid and biceps muscles, snap‐frozen at resting length, were cryosectioned, indirectly immunolabeled with fluorescent antibodies to sarcolemmal and myofibrillar markers, and examined with confocal microscopy to localize the immunolabeled proteins. Glutaraldehyde‐fixed samples were stained with heavy metals, embedded, thin‐sectioned, and examined with electron microscopy to determine the relationship between the sarcolemma and the underlying myofibrils.

Results

Confocal microscopy showed that some of the structures at the sarcolemma in FSHD samples were misaligned with respect to the underlying contractile apparatus. Electron microscopy showed a significant increase in the distance between the sarcolemma and the nearest myofibrils, from less than 100nm in controls to values as high as 550nm in FSHD.

Interpretation

Our results show that the pathophysiology of FSHD includes novel changes in the organization of the sarcolemma and its association with nearby contractile structures and suggest that, as in other muscular dystrophies, the integrity of the sarcolemma may be compromised in FSHD. Ann Neurol 2006;59:289–297
Severe episodic neurological deficits and permanent mental retardation in a child with a novel FHM2 ATP1A2 mutation
Authors: Vanmolkot K. R. J. , Stroink H. , Koenderink J. B. , Kors E. E. , van den Heuvel J. J. M. W. , van den Boogerd E. H. , Stam A. H. , Haan J. , De Vries B. B. A. , Terwindt G. M. , Frants R. R. , Ferrari M. D. , van den Maagdenberg A. M. J. M.
Published: January 2006

Objective

Attacks of familial hemiplegic migraine (FHM) are usually associated with transient, completely reversible symptoms. Here, we studied the ATP1A2 FHM2 gene in a young girl with episodes of both very severe and transient neurological symptoms that were triggered by mild head trauma as well as permanent mental retardation. Her family members suffered from hemiplegic and confusional migraine attacks.

Methods

Mutation analysis of the ATP1A2 gene was performed by direct sequencing of all exons and flanking intronic regions, using genomic DNA of the proband. Functional consequences of the mutation were analyzed by cellular survival assays.

Results

We identified a novel G615R ATP1A2 mutation in the proband and several of her family members. Functional analysis of mutant Na,K‐ATPase in cellular survival assays showed a complete loss‐of‐function effect.

Interpretation

Permanent mental retardation in children may be caused by ATP1A2 mutations. Ann Neurol 2006;59:310–314
The human immunodeficiency virus reduces network capacity: Acoustic noise effect
Authors: Tomasi Dardo , Chang Linda , de Castro Caparelli Elisabeth , Telang Frank , Ernst Thomas
Published: January 2006

Objective

Increased acoustic noise (AN) during working memory leads to increased brain activation in healthy individuals and may have greater impact in human immunodeficiency virus (HIV) patients.

Results

Compared with control subjects, HIV patients showed reduced AN activation and lower neuronal marker N‐acetylaspartate in prefrontal and parietal cortices. Competing use of the working memory network between AN and cognitive load showed lower dynamic range of the hemodynamic responses in prefrontal and parietal cortices in HIV patients.

Interpretation

These findings suggest that reduced reserve capacity of the working memory network in HIV patients and additional stress (eg, AN) might exhaust the impaired network for more demanding tasks. Ann Neurol 2006;59:419–423
Mild‐onset presentation of Canavan's disease associated with novel G212A point mutation in aspartoacylase gene
Authors: Janson Christopher G. , Kolodny Edwin H. , Zeng Bai‐Jin , Raghavan Srinivasa , Pastores Gregory , Torres Paola , Assadi Mitra , McPhee Scott , Goldfarb Olga , Saslow Beth , Freese Andrew , Wang D. J. , Bilaniuk Larissa , Shera David , Leone Paola
Published: January 2006

We describe two sisters with a mild‐onset variant of Canavan's disease who presented at age 50 and 19 months with developmental delay but without macrocephaly, hypotonia, spasticity, or seizures. Remarkably, both patients had age‐appropriate head control, gross motor development, and muscle tone. There were very mild deficits in fine motor skills, coordination, and gait. Both sisters had a history of strabismus, but otherwise vision was normal. The older child showed evidence of mild cognitive and social impairment, whereas language and behavior were normal for age in the infant. Both patients were found to be compound heterozygotes for C914A (A305E) and G212A (R71H) mutations in ASPA. Like all other known ASPA mutations, this previously unknown G212A mutation appears to have low absolute enzyme activity. Nevertheless, it is associated in these patients with an extremely benign phenotype that is highly atypical of Canavan's disease. Biochemical and clinical data were evaluated using a generalized linear mixed model generated from 25 other subjects with Canavan's disease. There were statistically significant differences in brain chemistry and clinical evaluations, supporting a distinct variant of Canavan's disease. Future studies of ASPA enzyme structure and gene regulation in these subjects could lead to a better understanding of Canavan's pathophysiology and improvements in ASPA gene therapy Ann Neurol 2006;59:428–431
Biochemical and pathological characterization of Lrrk2
Authors: Giasson Benoit I. , Covy Jason P. , Bonini Nancy M. , Hurtig Howard I. , Farrer Matthew J. , Trojanowski John Q. , Van Deerlin Vivianna M.
Published: January 2006

Objective

Mutations in leucine‐rich repeat kinase 2 (LRRK2) recently have been identified as the most common genetic cause of late‐onset sporadic and familial Parkinson's disease (PD). The studies herein explore the biological and pathological properties of Lrrk2.

Methods

Genetic analysis was performed to identify autopsied patients with the most common Lrrk2 mutation (G2019S). Using an antibody specific to Lrrk2, the biochemical and immunocytochemical distribution of Lrrk2 was assessed.

Results

Three patients with the G2019S Lrrk2 mutation were identified. Two patients demonstrated classic PD with Lewy bodies, although concurrent pathological changes consistent with Alzheimer's disease were also present in one of these individuals. The third patient was characterized by parkinsonism without Lewy bodies but demonstrated dystrophic neurites in the substantia nigra intensely stained for Lrrk2. Lrrk2 accumulations were unique to this patient and Lrrk2 was not detected in other types of pathological inclusions. Biochemical analysis showed that Lrrk2 is predominantly a soluble approximately 250kDa cytoplasmic protein expressed throughout the brain but also in many other organs.

Interpretation

The reasons for the selective predisposition of patients with mutations in LRRK2 to develop parkinsonism remains unclear, but Lrrk2 mutations may prime select neuronal populations to cellular insults that can lead to aberrant protein aggregation. Ann Neurol 2006;59:315–322
Broca's arrow: Evolution, prediction, and language in the brain
Authors: Cooper David L.
Published: January 2006

Brodmann's areas 44 and 45 in the human brain, also known as Broca's area, have long been associated with language functions, especially in the left hemisphere. However, the precise role Broca's area plays in human language has not been established with certainty. Broca's area has homologs in the great apes and in area F5 in monkeys, which suggests that its original function was not linguistic at all. In fact, great ape and hominid brains show very similar left‐over‐right asymmetries in Broca's area homologs as well as in other areas, such as homologs to Wernicke's area, that are normally associated with language in modern humans. Moreover, the so‐called mirror neurons are located in Broca's area in great apes and area F5 in monkeys, which seem to provide a representation of cause and effect in a primate's environment, particularly its social environment. Humans appear to have these mirror neurons in Broca's area as well. Similarly, genetic evidence related to the FOXP2 gene implicates Broca's area in linguistic function and dysfunction, but the gene itself is a highly conserved developmental gene in vertebrates and is shared with only two or three differences between humans and great apes, five between humans and mice, and eight between humans and songbirds. Taking neurons and portions of the brain as discrete computational segments in the sense of constituting specific Turing machines, this evidence points to a predictive motor and conceptual function for Broca's area in primates, especially for social concepts. In human language, this is consistent with evidence from typological and cognitive linguistics. Anat Rec (Part B: New Anat) 289B:9–24, 2006. © 2006 Wiley‐Liss, Inc.
Subcellular, cellular, and circuit mechanisms underlying classical conditioning in Hermissenda crassicornis
Authors: Blackwell Kim T.
Published: January 2006

A breakthrough for studying the neuronal basis of learning emerged when invertebrates with simple nervous systems, such as the sea slug Hermissenda crassicornis, were shown to exhibit classical conditioning. Hermissenda learns to associate light with turbulence: prior to learning, naive animals move toward light (phototaxis) and contract their foot in response to turbulence; after learning, conditioned animals delay phototaxis in response to light. The photoreceptors of the eye, which receive monosynaptic inputs from statocyst hair cells, are both sensory neurons and the first site of sensory convergence. The memory of light associated with turbulence is stored as changes in intrinsic and synaptic currents in these photoreceptors. The subcellular mechanisms producing these changes include activation of protein kinase C and MAP kinase, which act as coincidence detectors because they are activated by convergent signaling pathways. Pathways of interneurons and motorneurons, where additional changes in excitability and synaptic connections are found, contribute to delayed phototaxis. Bursting activity recorded at several points suggest the existence of small networks that produce complex spatiotemporal firing patterns. Thus, the change in behavior may be produced by a nonlinear transformation of spatiotemporal firing patterns caused by plasticity of synaptic and intrinsic channels. The change in currents and the activation of PKC and MAPK produced by associative learning are similar to those observed in hippocampal and cerebellar neurons after rabbit classical conditioning, suggesting that these represent general mechanisms of memory storage. Thus, the knowledge gained from further study of Hermissenda will continue to illuminate mechanisms of mammalian learning. Anat Rec (Part B: New Anat) 289B:25–37, 2006. © 2006 Wiley‐Liss, Inc.
The sensitivity of human event‐related potentials and reaction time to mobile phone emitted electromagnetic fields
Authors: Hamblin D.L. , Croft R.J. , Wood A.W. , Stough C. , Spong J.
Published: January 2006

There is some evidence to suggest that exposure to mobile phones (MPs) can affect neural activity, particularly in response to auditory stimuli. The current investigation (n = 120) aimed to test recent findings in this area, namely that N100 amplitude and latency would decrease, and that P300 latency and reaction time (RT) would increase under active relative to sham exposure during an auditory task. Visual measures were also explored. A double blind, counterbalanced, crossover design was employed where subjects attended two sessions 1 week apart. In both sessions participants (1) performed auditory and visual oddball tasks while electroencephalogram (EEG) was recorded with a MP set to sham exposure mounted over the temporal region, and (2) performed the same tasks while the handset was set to active/sham. When active, the MP transmitted for 30 min at 895 MHz (average power 250 mW, pulse modulated at 217 Hz, average SAR 0.11 W/kg). Paired t‐tests compared difference scores from the sham/sham session to those from the sham/active condition. The study was designed to detect differences of ${1\over4}$ of a standard deviation with a power of 0.80. There was no significant difference between exposure conditions for any auditory or visual event related potential (ERP) component or RT. As previous positive findings were not replicated, it was concluded that there is currently no evidence that acute MP exposure affects these indices of brain activity. Bioelectromagnetics 27:265–273, 2006. © 2006 Wiley‐Liss, Inc.
CNS viral infection diverts homing of antibody‐secreting cells from lymphoid organs to the CNS
Authors: Tschen Shuen‐Ing , Stohlman Stephen A. , Ramakrishna Chandran , Hinton David R. , Atkinson Roscoe D. , Bergmann Cornelia C.
Published: January 2006

Neurotropic coronavirus infection of mice results in acute encephalomyelitis followed by viral persistence. Whereas cellular immunity controls acute infection, humoral immunity regulates central nervous system (CNS) persistence. Maintenance of serum Ab was correlated with tissue distribution of virus‐specific Ab‐secreting cells (ASC). Although virus‐specific ASC declined in cervical lymph node and spleen after infectious virus clearance, virus‐specific serum Ab was sustained at steady levels, with a delay in neutralizing Ab. Virus‐specific ASC within the CNS peaked rapidly 1 wk after control of infectious virus and were retained throughout chronic infection, consistent with intrathecal Ab synthesis. Surprisingly, frequencies of ASC in the BM remained low and only increased gradually. Nevertheless, virus‐specific ASC induced by peripheral infection localized to both spleen and BM. The data suggest that CNS infection provides strong stimuli to recruit ASC into the inflamed tissue through sustained up‐regulation of the CXCR3 ligands CXCL9 and CXCL10. Irrespective of Ag deprivation, CNS retention of ASC coincided with elevated BAFF expression and ongoing differentiation of class II+ to class II–CD138+CD19+ plasmablasts. These results confirm the CNS as a major ASC‐supporting environment, even after resolution of viral infection and in the absence of chronic ongoing inflammation.
Structural and Dynamic Studies of Zinc, Gallium, and Cadmium Complexes of a Dicarboxylate Pendant‐Armed Cross‐Bridged Cyclen
Authors: Niu Weijun , Wong Edward H. , Weisman Gary R. , Peng Yijie , Anderson Carolyn J. , Zakharov Lev N. , Golen James A. , Rheingold Arnold L.
Published: January 2006

Inadvertently, the wrong X‐ray structure was reported1 for the Zn‐CB‐DO2A complex. Instead, the structural data for a related zinc complex was actually presented. The first paragraph of the section X‐ray Structural Data and Figure 5 on page 3312, Table 1 on page 3313, the last two sentences of the paragraph [Zn·1](NaClO4)1.5 and Table 3 on page 3314, and the paragraph X‐ray Crystallography on page 3315 should be replaced as follows (in addition, a corrected X‐ray CIF file was deposited with the CCDC):
Postnatal expression of myostatin propeptide cDNA maintained high muscle growth and normal adipose tissue mass in transgenic mice fed a high‐fat diet
Authors: Yang Jinzeng , Zhao Baoping
Published: January 2006

Myostatin plays a robust, negative role in controlling muscle mass. A disruption of myostatin function by transgenic expression of its propeptide (the 5′region, 866 nucleotides) results in significant muscle growth (Yang et al., 2001. Mol Rep Dev 60:351–361). Studies from myostatin and the propeptide transgene mRNA indicated that myostatin mRNA was detected at day 10.5 postcoitum in fetal mice. Its level remained low, but increased by 180% during the postnatal fast‐growth period (day 0–10). An early, high‐level postnatal expression of the transgene was identified as being responsible for a highly muscled phenotype. High‐fat diet induces adiposity in rodents. To study the effects of dietary fat on muscle growth and adipose tissue fat deposition in the transgenic mice, we challenged the mice with a high‐fat diet (45% kcal fat) for 21 weeks. Transgenic mice showed 24%–50% further enhancement of growth on the high‐fat diet compared to the normal‐fat diet (P = 0.004) from 17 to 25 weeks of age. The total mass of the main muscles of transgenic mice showed a 27% increase on the high‐fat diet compared to the normal‐fat diet (P = 0.004), while the white adipose tissue mass of the transgenic mice was not significantly different from that of wild‐type mice fed a normal‐fat diet (P = 0.434). The high‐fat diet induced wild‐type mice developed 190% greater mass of white adipose tissues compared to the normal‐fat diet (P = 0.008), which primarily resulted from enlarged adipocytes. These results demonstrate that disruption of myostatin function by its propeptide shifted dietary fat utilization toward muscle tissues with minimal effects on adiposity. These results suggest that enhancing muscle growth by myostatin propeptide or other means during the early developmental stage may serve as an effective means for obesity prevention. Mol. Reprod. Dev. © 2006 Wiley‐Liss, Inc.
Multiple mapping method: A novel approach to the sequence‐to‐structure alignment problem in comparative protein structure modeling
Authors: Rai Brajesh K. , Fiser András
Published: January 2006

A major bottleneck in comparative protein structure modeling is the quality of input alignment between the target sequence and the template structure. A number of alignment methods are available, but none of these techniques produce consistently good solutions for all cases. Alignments produced by alternative methods may be superior in certain segments but inferior in others when compared to each other; therefore, an accurate solution often requires an optimal combination of them. To address this problem, we have developed a new approach, Multiple Mapping Method (MMM). The algorithm first identifies the alternatively aligned regions from a set of input alignments. These alternatively aligned segments are scored using a composite scoring function, which determines their fitness within the structural environment of the template. The best scoring regions from a set of alternative segments are combined with the core part of the alignments to produce the final MMM alignment. The algorithm was tested on a dataset of 1400 protein pairs using 11 combinations of two to four alignment methods. In all cases MMM showed statistically significant improvement by reducing alignment errors in the range of 3 to 17%. MMM also compared favorably over two alignment meta‐servers. The algorithm is computationally efficient; therefore, it is a suitable tool for genome scale modeling studies. Proteins 2006. © 2006 Wiley‐Liss, Inc.
Kernel Functions for Attributed Molecular Graphs – A New Similarity‐Based Approach to ADME Prediction in Classification and Regression
Authors: Fröhlich Holger , Wegner Jörg. K. , Sieker Florian , Zell Andreas
Published: January 2006

Kernel methods, like the well‐known Support Vector Machine (SVM), have received growing attention in recent years for designing QSAR models that have a high predictive strength. One of the key concepts of SVMs is the usage of a so‐called kernel function, which can be thought of as a special similarity measure. In this paper we consider kernels for molecular structures, which are based on a graph representation of chemical compounds. The similarity score is calculated by computing an optimal assignment of the atoms from one molecule to those of another one, including information on specific chemical properties, membership to a substructure (e.g., aromatic ring, carbonyl group, etc.) and neighborhood for each atom. We show that by using this kernel we can achieve a generalization performance comparable to a classical model with a few descriptors, which are a‐priori known to be relevant for the problem, and significantly better results than with and without performing an automatic descriptor selection. For this purpose we investigate ADME classification and regression datasets for predicting bioavailability (Yoshida), Human Intestinal Absorption (HIA), Blood‐Brain‐Barrier (BBB) penetration and a dataset consisting of four different inhibitor classes (SOL). We further explore the effect of combining our kernel with a problem‐dependent descriptor set. We also demonstrate the usefulness of an extension of our method to a reduced graph representation of molecules, in which certain structural features, like, e.g., rings, donors or acceptors, are represented as a single node in the molecular graph.
Note on the Computation of Tetrachoric Correlation
Authors: Dunlap Jack W.
Published: January 2006

In tetrachoric correlation there is a four-fold distribution based on the four combinations of A’s and not —A’s and B’s and not —B’s. The analogous problem in test construction is that of determining the relationship between two items or test questions, upon which all individuals are scored pass or fail.
Experimental Study of Simple Structure
Authors: Thurstone L. L.
Published: January 2006

A battery of thirty-six tests was given to a group of high-school seniors. The factorial analysis reveals essentially the same primary factors that were found in previous studies. The test battery reveals a simple structure.
A Simple Procedure for Approximate Factor Analysis
Authors: Woodrow Herbert , Wilson Lawrence A.
Published: January 2006

A variation of the centroid method is described and illustrated. By the application of new rules for reflecting signs, it may be possible to reduce to insignificance the factor loadings of tests showing insignificant correlation (original or residual) with clusters of tests having relatively high intercorrelations. As a result, a factor common to any one of these clusters may be revealed by the centroid method itself with little or no need for rotation of axes or further calculations.
A Note on Item Analysis and the Criterion of Internal Consistency
Authors: Mosier Charles I.
Published: January 2006

The implications contained in Richardson's article on item analysis in March 1936 issue of Psychometrika are examined in the light of multiple factor theory. It is shown that item analysis is a necessary, but not a sufficient condition for the construction of a test which shall measure a single trait. The intercorrelations of certain items selected by a method of item analysis are examined, found to contain many zero and some negative correlations. Multiple factor analysis showed that eight traits were measured by the items which had been asserted to measure only one.
A Note on Factor Analysis by the Method of Principal Axes
Authors: Lev Joseph
Published: January 2006

The resolution of a set of variables into principal components may be performed upon variables having arbitrary variances, or upon variables obtained from these by reduction of all variances to unity. The two procedures do not yield the same results even if the principal components are reduced to unit variance in both cases, except when the original variances are all equal.
The Technique of Path Coefficients
Authors: Engelhart Max D.
Published: January 2006

A derivation of equations fundamental to the technique of path coefficients is given. Suggestions are made with respect to the calculations required in the use of the technique. The relations of the technique to those of partial correlation, semi-partial correlation, part correlation, multiple correlation, and factor analysis are discussed. Some consideration is given to the merits and limitations of the technique of path coefficients.
A Note on Rotation of Axes
Authors: Harsh Charles M.
Published: January 2006

Differences in magnitude among the communalities of a set of tests may influence the convergence of successive approximations to the limiting hyperplanes of the configuration. A slight alteration in technique is presented, which may be useful in avoiding this effect and perhaps hastening convergence.
Ability, Motivation, and Speed
Authors: Thurstone L. L.
Published: January 2006

The relations between ability, motivation, and speed in a mental task are represented by a psychometric surface. Ability of a subject is defined as the degree of difficulty for which the probability is 1/2 that he will complete the task in infinite time. Motivation affects the rate at which mental work is done, but not the altitude of performance. Suggestions towards experimental work are made.
A Factor Analysis of Certain Neurotic Symptoms
Authors: Mosier Charles I.
Published: January 2006

In an attempt to investigate the concept of neurotic tendency thirty-nine of the forty-two most discriminative items in the Thurstone Neurotic Inventory were administered as a questionnaire to a group of five hundred male college students. An analysis of the table of intercorrelations by Thurstone's centroid method showed that eight factors were sufficient to account for the observed intercorrelations with negligible residuals. The eight centroid factors were then transformed into a simple structure. It is concluded that a single trait of neurotic tendency cannot be postulated and tentative hypotheses are formed as to the nature of the primary traits revealed by the analysis.

Readministering the same test to the same students a week later showed a high consistency of response both on the test as a whole, and on the individual items.
Discussion of a Set of Points in Terms of their Mutual Distances
Authors: Young Gale , Householder A. S.
Published: January 2006

Necessary and sufficient conditions are given for a set of numbers to be the mutual distances of a set of real points in Euclidean space, and matrices are found whose ranks determine the dimension of the smallest Euclidean space containing such points. Methods are indicated for determining the configuration of these points, and for approximating to them by points in a space of lower dimensionality.
Simplified Calculation of Principal Components
Authors: Hotelling Harold
Published: January 2006

The resolution of a set of n tests or other variates into components γn, each of which accounts for the greatest possible portion γ1, γ2, ..., of the total variance of the tests unaccounted for by the previous components, has been dealt with by the author in a previous paper. Such “factors,” on account of their analogy with the principal axes of a quadric, have been called principal components. The present paper describes a modification of the iterative scheme of calculating principal components there presented, in a fashion that materially accelerates convergence. The application of the iterative process is not confined to statistics, but may be used to obtain the magnitudes and orientations of the principal axes of a quadric or hyperquadric in a manner which will ordinarily be far less laborious than those given in books on geometry. This is true whether the quadrics are ellipsoids or hyperboloids; the proof of convergence given in an earlier paper is applicable to all kinds of central quadrics.
Contribution to the Mathematical Biophysics of Visual Perception with Special Reference to the Theory of Aesthetic Values of Geometrical Patterns
Authors: Rashevsky N.
Published: January 2006

On the basis of previous mathematico-biophysical studies, a theory of visual perception is outlined. The theory is applied to the aesthetic values of polygonal patterns and found in fair agreement with experimental results.
Conditioning Circuits
Authors: Householder A. S.
Published: January 2006

A circuit of mutually exciting neurones capable of approaching and maintaining a state of permanent excitation has been described by Rashevsky as a possible mechanism for the production of conditioned reflexes. The mode of approach of such a circuit to the steady state is examined in some detail under slightly more general assumptions, and an estimate is made of the order of magnitude of the time required to reach this state.
A Significance Test for Minimum Rank in Factor Analysis
Authors: Hoel Paul G.
Published: January 2006

This paper presents a new method of determining the minimum rank in factor analysis, appropriate to the principal axes solution. The new method is compared with a former method which, with some adjustment, is more convenient for the centroid approach. Both methods are applied to two familiar examples.
Neuron Circuits: The Self-Exciting Neuron
Authors: Landahl H. D. , Householder A. S.
Published: January 2006

Conditions are determined under which a single self-exciting neuron can reach a state of permanent excitation, in the case that the neuron develops both an excitatory and an inhibitory substance as well as in the case that it develops only a single, excitatory substance. In case both substances are developed it is possible to have periodic solutions, a possibility which does not arise when the circuit consists of neurons, or of a neuron, developing only an excitatory substance.
Alternative Views on Correlations between Persons
Authors: Burt Cyril , Stephenson William
Published: January 2006

The article discusses the general principles involved in factorizing correlations between persons, and compares the special techniques put forward by Burt and Stephenson respectively. The chief points of agreement and disagreement are summarized. In statistical procedure the two writers prove to be largely in accord; but they differ over the psychological and the methodological implications, the chief source of divergence being the so-called “reciprocity principle.”
Matrix Approximations and Subspace Fitting
Authors: Young Gale
Published: January 2006

The problem of fitting a least-squares linear subspace to a higher dimensional set of points is solved by the use of matrix approximation results, both when the subspace is required to pass through a given point, and when it is not so restricted. In the latter case the subspace is shown to pass through the centroid of the point set. It is noted that the principal axes of the set of points enter into the problem in a natural manner.
An Empirical Study of the Effect of Heterogeneous Within-Groups Variance upon Certain F-Tests of Significance in Analysis of Variance
Authors: Godard R. H. , Lindquist E. F.
Published: January 2006

In the application of the analysis of variance to data obtained in educational methods experiments which involve several classes of several schools, one assumption is that of homogeneity in the variances of pupil scores from school to school. It is shown that such variances on representative educational achievement tests are heterogeneous. The effects of this heterogeneity upon the F-tests of significance commonly employed in methods experiments are investigated by comparing the actual distribution of F values for a large number of “experiments” involving marked heterogeneity with a theoretical distribution based on the assumption of homogeneity. Although the findings, which vary somewhat with the type of variance ratio, are not entirely conclusive, they apparently demonstrate that departure from homogeneity does not invalidate the use of the customary F-tests for evaluating results of the typical methods experiment.
Concerning the Determination of Trait Variability
Authors: Preston Malcolm G.
Published: January 2006

An analytic technique for the study of trait variability is presented. An expression for the average variance from test to test and an expression for the variance of these variances are derived in terms of the number of tests and the intercorrelations between them, and limiting cases are examined. The question of the true relationship between the nature of the distribution of test scores in a sample of N persons and the nature of the distribution of n traits in a single individual is discussed, and other problems are introduced.
A Method for Approximating the Average Intercorrelation Coefficient by Correlating the Parts with the Sum of the Parts
Authors: Babitz Milton , Keys Noel
Published: January 2006

It is noted that the average inter-item correlation, which represents the internal consistency of a test, yields a unique estimate of test reliability. A close approximation to this average is given by a formula which requires the correlation of each item with the total score and the standard deviation of each item. The formula is especially useful in those instances where the number of items is small and where the variation in item sigmas should not be neglected.
Contributions to the Mathematical Theory of Human Relations. IV
Authors: Rashevsky N.
Published: January 2006

An attempt is made to define and treat analytically the concept of individual freedom in a society. Two possible definitions are briefly discussed. One takes as a measure of freedom the ratio (w0 − w)w0, where w0 is the maximum amount of work that a person can physically perform per unit time and w is the amount of work which he has actually to perform per unit time in a given society. The other definition takes as a measure of freedom that fraction of an individual's time during which he can indulge in any activity of his own choice without interfering with other individuals. Expressions are derived by way of illustration, giving the individual freedom in terms of other parameters which characterize the social structure.
Some Remarks on the Kuder-Richardson Reliability Coefficient
Authors: Dressel Paul L.
Published: January 2006

The Kuder-Richardson reliability coefficient is derived in a manner independent of that originally given. Various alternative forms applicable to special situations are exhibited with the purpose of making them available to others interested in using this formula. A simplification in computation is suggested for use with a calculating machine.
Influence of Chance Error on Simple Structure: An Empirical Investigation of the Effect of Chance Error and Estimated Communalities on Simple Structure in Factorial Analysis
Authors: Mosier Charles I.
Published: January 2006

Correlation coefficients derived from an hypothetical simple structure for twenty tests and four factors were “loaded” with chance error components. Centroid analyses and rotations to give least square determinations of the hypothetical simple structure were made for several conditions. It is concluded that the experimental situation of inaccurate coefficients and estimated communalities permits accurate determination of primary trait loadings provided that the rank of the centroid matrix is equal to or greater than that of the underlying primary trait matrix. Of several criteria for the completeness of factorization which were tested, none was wholly satisfactory.
On the Use of Mathematics in Psychological Theory (Concluded from Previous Issue)
Authors: Brown J. F.
Published: January 2006

The topological concepts allow us to assign individuals and goals to certain spatial regions. They allow us to designate what locomotions are possible for an individual and what regions must be traversed in attaining a definite goal. But the topological concepts alone tell us nothing of the actual locomotions performed in psychological activities. So far we have seen that the position of the individual at the start of the psychological activity may be defined in reference to this. Psychological activities may be ordered to locomotions. The individual in this sense has the character of a thing. The space through which the locomotion occurs has the properties of a medium. (Cf. Heider (10). In physical problems where the field construct is used, one may make this same distinction. Bodies falling in the earth’s gravitational field have the properties of things, while the atmosphere is to be characterized as a medium. Similarly in the electro-static field, the isolated conductors have the properties of things and the field has those of a medium.
The Analysis of Variance and Covariance Techniques in Relation to the Conventional Formulas for the Standard Error of a Difference
Authors: Engelhart Max D.
Published: January 2006

In this paper it is demonstrated that the analysis of variance techniques yield results equivalent to the calculation of t by means of expressions based on the short or the long formula. It is also shown that the covariance technique gives results equivalent to those obtained by means of the formula for t which should be used with matched groups. The conditions necessary for equivalent results are such that the conventional formulas for t would normally be used rather than the variance or covariance techniques. However, a knowledge of the relationships described in this paper should contribute to one's understanding of the variance and covariance techniques.
The Simultaneous Prediction of Any Number of Criteria by the Use of a Unique Set of Weights
Authors: Kurtz Albert K.
Published: January 2006

When several criteria are available, it is ordinarily necessary (1) to select one of them as the criterion, (2) to use several and thus arrive at several different sets of weights, or (3) to combine them into a single measure. A formula is derived for the determination of a unique set of weights. The use of these weights will produce the highest possible average coefficient of correlation between the various criteria and two (or more) weighted independent variables. If desired, the criteria may be assigned any predetermined weights. The weights then derived for the independent variables are such that the weighted average of the correlation coefficients between the various criteria and the independent variable composite will be a maximum. In the use of these formulas, no assumptions are necessary regarding the interrelationships existing among the criteria and it is not necessary to compute the intercorrelations among the criteria. A numerical example is included.
Studies in the Learning Function
Authors: Wiley L. E. , Wiley A. M.
Published: January 2006

From Thurstone's theoretical learning curve, a solution for the difficulty of the problem and the learning constant of the subject has been developed. The curve is an equilateral hyperbola. Therefore the semi-major axis represents the learning situation in one constant. The vertex of the curve is a point where all of the animals are equated, since they are all making errors at the rate of one error per trial.
Nomograph for Point Biserial r, Biserial r, and Fourfold Correlations
Authors: Kuder G. F.
Published: January 2006

A nomograph for the computation of point biserial r, biserial r, and fourfold correlation coefficients is presented, with instructions for use.
Response Relay
Authors: Libby J. E. P.
Published: January 2006

Controlled by microphone, photocell, or keys, the described instrument operates a chronoscope, chronograph, etc., together with a projector, bell, light, or other stimulus requiring up to 200 watts.
A Note on the Computation of Biserial r in Item Validation
Authors: DuBois Philip H.
Published: January 2006

A method of computing biserial coefficients of correlation through the use of punch card tabulating equipment is presented. Each item is assigned a separate column and successes are punched 1. By arranging the cards on the criterion variable and obtaining progressive sums on several columns simultaneously, it is possible to obtain data for several correlations in one run of the cards through the machine.
Boundary Conditions in the Common-Factor-Space, in the Factorial Analysis of Ability
Authors: Thomson Godfrey H.
Published: January 2006

The author arrives at a simple rule for ascertaining when a matrix of correlations, with communalities reducing it to minimum rank, cannot be analyzed into factors such that every column of loadings has at least as many zeros as the number of common factors, as required by Thurstone. A more exact but arithmetically tedious rule is also deduced from Ridley Thompson's boundary conditions, and a correction is made to the latter.
The Method of Minimum Variation for the Combination of Criteria
Authors: Edgerton Harold A. , Kolbe Laverne E.
Published: January 2006

The problem of weighting separate criterion variates is solved by minimizing the differences among the standard scores of the individual upon the various measures. The method is compared with Horst's procedure of maximizing the inter-individual differences. An application is made to personnel data.
The Content Reliability of a Test
Authors: Gulliksen Harold
Published: January 2006

The content unreliability of an essay test is the error due to the items used or the content of the test. The reader unreliability is due to variation in judgment of the persons who read and score the essay test. The content reliability of an essay test is accordingly defined as being independent of the reader reliability. Formulae are derived for the reader reliability and for the content reliability. The content reliability is found to be equal to the geometric mean of the test reliabilities computed from the scores assigned by the two readers, divided by the reader reliability.