Orthogonal representations and connectivity of graphs

AbstractIt is proved that a graph on n nodes is k-connected if and only if its nodes can be represented by real vectors in dimension n – k such that (a) nonadjacent nodes are represented by orthogonal vectors and (b) any n – k of them are linearly independent. We show that the closure of the set of all representations with properties (a) and (b) is irreducible as an algebraic variety, and study the question of irreducibility of the variety of all representations with property (a)

Histological Chages of Testis and Caput Epididymis in the Goat after Cannulation of the Rete Testis

雄ヤギ5頭を用い, 精巣網カテーテル装着手術後の精巣および精巣上体頭の組織構造を観察するとともに精巣静脈血中のテストステロン濃度を調べた。カテーテル装着手術後の精巣は, いずれも萎縮し, 正常な精子形成過程が観察される精細管は少なかった。また, ライディヒ細胞の形態や染色性には異常は認められなかった。一方, 精巣上体頭では, 精巣上体管が萎縮し, 主細胞の高さは無傷のものよりも有意に減少した。同様の組織構造の変化は, 精巣輸出管を切除した場合の精巣および精巣上体頭でも認められた。精巣静脈血中のテストステロン濃度は無傷の場合94.4ng/mlであり, カテーテル装着手術後では86.5∿342.8ng/mlであった。 / The testis and caput epididymis of the goat after cannulation of the rete testis or efferentiectomy were examined histologically. The concentration of testosterone in testicular venous blood collected from the same animals was also measured by radioimmunoassay. After cannulation, seminiferous tubules showed a sign of degeneration, although no morphological change of Leydig cells was observed. Epididymal ducts were severely atrophied and the height of principal epithelial cells was significantly decreased. A similar damage was observed in the testis and epididymis after efferentiectomy. When the efferent duct bundle had been incompletely ligated at cannulation, or rete testis catheter was kept in place until sampling time, damages in the testis were less severe. And in the former case the epididymis was impaired less severely. The concentration of testosterone in testicular venous blood collected from an intact animal was 94.4ng/ml, while that obtained after cannulation was 86.5-342.8ng/ml. These results suggest that degeneration of germ cells in seminiferous tubules observed after cannulation of the rete testis or efferentiectomy may be caused by stagnation of rete testicular fluid in the tubules, and that testosterone in the fluid plays important roles in the maintenance of morphology and function of the principal cells in the caput epididymis

Pseudorandomness for Regular Branching Programs via Fourier Analysis

We present an explicit pseudorandom generator for oblivious, read-once, permutation branching programs of constant width that can read their input bits in any order. The seed length is $O(\log^2 n)$, where $n$ is the length of the branching program. The previous best seed length known for this model was $n^{1/2+o(1)}$, which follows as a special case of a generator due to Impagliazzo, Meka, and Zuckerman (FOCS 2012) (which gives a seed length of $s^{1/2+o(1)}$ for arbitrary branching programs of size $s$). Our techniques also give seed length $n^{1/2+o(1)}$ for general oblivious, read-once branching programs of width $2^{n^{o(1)}}$, which is incomparable to the results of Impagliazzo et al.Our pseudorandom generator is similar to the one used by Gopalan et al. (FOCS 2012) for read-once CNFs, but the analysis is quite different; ours is based on Fourier analysis of branching programs. In particular, we show that an oblivious, read-once, regular branching program of width $w$ has Fourier mass at most $(2w^2)^k$ at level $k$, independent of the length of the program.Comment: RANDOM 201

Employee engagement, human resource management practices and competitive advantage

AbstractPurpose - The purpose of this paper is to argue in support of a model that shows how four key HRM practices focused on engagement influence organizational climate, job demands and job resources, the psychological experiences of safety, meaningfulness and availability at work, employee engagement, and individual, group and organizational performance and competitive advantage.Design/methodology/approach - This conceptual review focuses on the research evidence showing interrelationships between organizational context factors, job factors, individual employee psychological and motivational factors, employee outcomes, organizational outcomes and competitive advantage. The proposed model integrates frameworks that have previously run independently in the HR and engagement literatures.Findings - The authors conclude that HRM practitioners need to move beyond the routine administration of annual engagement surveys and need to embed engagement in HRM policies and practices such personnel selection, socialization, performance management, and training and development.Practical implications - The authors offer organizations clear guidelines for how HR practices (i.e. selection, socialization, performance management, training) can be used to facilitate and improve employee engagement and result in positive outcomes that will help organizations achieve a competitive advantage.Originality/value - The authors provide useful new insights for researchers and management professionals wishing to embed engagement within the fabric of HRM policies and practices and employee behaviour, and organizational outcomes.<br /

Parasitic dermoid cyst managed laparoscopically in a 29-year-old woman: a case report

<p>Abstract</p> <p>Introduction</p> <p>Dermoid cysts are one of the most frequently occurring ovarian cysts; parasitic dermoid cysts, however, are extremely rare.</p> <p>Case presentation</p> <p>We report a case of a 29-year-old Japanese woman with an incidental finding of an adnexal mass on bimanual examination. Sonographic imaging reported an 8 cm mass in the Pouch of Douglas. This was found to be a parasitic dermoid cyst and was removed at laparoscopy.</p> <p>Conclusion</p> <p>We believe laparoscopy to be a safe and effective means of managing parasitic ovarian dermoid cysts.</p

Phase space quantization and Loop Quantum Cosmology: A Wigner function for the Bohr-compactified real line

We give a definition for the Wigner function for quantum mechanics on the Bohr compactification of the real line and prove a number of simple consequences of this definition. We then discuss how this formalism can be applied to loop quantum cosmology. As an example, we use the Wigner function to give a new quantization of an important building block of the Hamiltonian constraint.Comment: 26 pages, 3 figure

Revisiting the Direct Sum Theorem and Space Lower Bounds in Random Order Streams

Estimating frequency moments and $L_p$ distances are well studied problems in the adversarial data stream model and tight space bounds are known for these two problems. There has been growing interest in revisiting these problems in the framework of random-order streams. The best space lower bound known for computing the $k^{th}$ frequency moment in random-order streams is $\Omega(n^{1-2.5/k})$ by Andoni et al., and it is conjectured that the real lower bound shall be $\Omega(n^{1-2/k})$. In this paper, we resolve this conjecture. In our approach, we revisit the direct sum theorem developed by Bar-Yossef et al. in a random-partition private messages model and provide a tight $\Omega(n^{1-2/k}/\ell)$ space lower bound for any $\ell$-pass algorithm that approximates the frequency moment in random-order stream model to a constant factor. Finally, we also introduce the notion of space-entropy tradeoffs in random order streams, as a means of studying intermediate models between adversarial and fully random order streams. We show an almost tight space-entropy tradeoff for $L_\infty$ distance and a non-trivial tradeoff for $L_p$ distances

Isolated oxygen defects in 3C- and 4H-SiC: A theoretical study

Ab initio calculations in the local-density approximation have been carried out in SiC to determine the possible configurations of the isolated oxygen impurity. Equilibrium geometry and occupation levels were calculated. Substitutional oxygen in 3C-SiC is a relatively shallow effective mass like double donor on the carbon site (O-C) and a hyperdeep double donor on the Si site (O-Si). In 4H-SiC O-C is still a double donor but with a more localized electron state. In 3C-SiC O-C is substantially more stable under any condition than O-Si or interstitial oxygen (O-i). In 4H-SiC O-C is also the most stable one except for heavy n-type doping. We propose that O-C is at the core of the electrically active oxygen-related defect family found by deep level transient spectroscopy in 4H-SiC. The consequences of the site preference of oxygen on the SiC/SiO2 interface are discussed

Re-establishing glacier monitoring in Kyrgyzstan and Uzbekistan, Central Asia

Glacier mass loss is among the clearest indicators of atmospheric warming. The observation of these changes is one of the major objectives of the international climate monitoring strategy developed by the Global Climate Observing System (GCOS). Long-term glacier mass balance measurements are furthermore the basis for calibrating and validating models simulating future runoff of glacierised catchments. This is essential for Central Asia, which is one of the driest continental regions of the Northern Hemisphere. In the highly populated regions, water shortage due to decreased glacierisation potentially leads to pronounced political instability, drastic ecological changes and endangered food security. As a consequence of the collapse of the former Soviet Union, however, many valuable glacier monitoring sites in the Tien Shan and Pamir Mountains were abandoned. In recent years, multinational actors have re-established a set of important in situ measuring sites to continue the invaluable long-term data series. This paper introduces the applied monitoring strategy for selected glaciers in the Kyrgyz and Uzbek Tien Shan and Pamir, highlights the existing and the new measurements on these glaciers, and presents an example for how the old and new data can be combined to establish multi-decadal mass balance time series. This is crucial for understanding the impact of climate change on glaciers in this region