LLukas22/scidocs huggingface dataset:
Efficient Grounding for Modular Multilevel HVDC Converters (MMC) on the AC Side

An unbalance voltage between a positive pole and negative pole will exist for a long time in an ungrounded modular multilevel converter (MMC) HVDC transmission system. A zig-zag transformer has been proposed to construct an artificial neutral point and keep voltage balance between the positive pole and the negative pole. An efficient grounding system consists of the zig-zag transformer and the neutral grounding resistor. In this paper, the different impedances, including positive-, negative-, zero-sequence impedance, and dc current impedance, have been analyzed, respectively. Then, the computer simulations have been performed to evaluate the characteristic of the zig-zag transformer under normal voltage, zero-sequence voltage and unbalanced dc voltage, respectively. The simulation results show that the zig-zag transformer can effectively balance the unbalanced voltage in dc side of the MMC under different work conditions; the zero-sequence impedance is low and zero-sequence current is convenient for the detection of a single-phase fault; the power consumption of the neutral grounding resistor is of a light rating, and the cooling of the resistor is unnecessary. The method presented in this paper proves to be an efficient grounding method for the MMC-HVDC transmission system.
The Effects of Functional Training on Pain, Function, and Performance in Taekwondo Players with Mechanical Low Back Pain

Background: The aim of this study was to assess the effects of functional training (FT) on pain, function, and performance in elite male taekwondo players with CMLBP. Method: 27 elite male taekwondo players (mean ± standard deviation: age 24.4 ± 4.9 years, body mass 75.7 ± 15.1 kg, height 181.4 ± 7.8 cm) were allocated to two experimental (n = 15) and control (n = 12) groups. The eight-week FT was divided into four distinct phases for the subjects of the experimental group. Variables of pain and function were assessed by Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI), respectively. The movement time of Ap Douliou Chagi kick (MTAK) and speed of Ap Douliou Chagi kick (SAK) was used for the variable of performance. Results: Considering the results of pre-test before the implementation of the scores protocol, after FT intervention, VAS (p = 0.004), ODI (p = 0.005), MTAK on the right leg (p = 0.029) and the left leg (p = 0.013) decreased and SAK on both legs (p = 0.000) increased significantly in comparison with the control group. Conclusion: It is assumed that FT can reduce the pain intensity and improve the function and performance in taekwondo players.
Variability and Determinants of Occupational Noise Exposure Among Iron and Steel Factory Workers in Tanzania

Background
Machines, processes, and tasks in the iron and steel factories may produce noise levels that are harmful to hearing if not properly controlled. Studies documenting noise exposure levels and related determinants in sub-Saharan Africa, including Tanzania are lacking. The aim of this study was to document noise exposure and to identify determinants of noise exposure with a view to establishing an effective hearing conservation programme.


Methods
A walk-through survey was conducted to describe the working environment in terms of noise sources in four metal factories (A-D) in Tanzania. Noise measurements were conducted by both personal, full-shift noise measurements (8 h) using dosimeters and area measurements (10-s measurements) using a sound level meter. A total of 163 participants had repeated personal noise measurements (Factory A: 46 participants, B: 43, C: 34, and D: 40). Workers were randomly selected and categorized into 13 exposure groups according to their job. Linear mixed effects models were used to identify significant determinants of noise exposure in the furnace section and the rolling mill section.


Results
The average personal noise exposure in the four factories was 92.0 dB(A) (range of job group means; 85.4-96.2 dB(A)) (n = 326). Personal exposure was significantly higher in the rolling mill section (93.0 dB(A)) than in the furnace section (89.6 dB(A)). Among the job groups, the cutters located in the rolling mill section had the highest noise exposure (96.2 dB(A)). In the furnace section, furnace installation (below the ground floor), manual handling of raw materials/billets/crowbars, and billet weighing/transfer were significant determinants explaining 40% of the total variance in personal noise exposure. In the rolling mill section, the size of the cutting machine, steel billet weight and feeding re-heating furnace explained 46% of the total variance in personal noise exposure. The mean noise level of the area measurements was 90.5 dB(A) (n = 376).


Conclusion
Workers in the four iron and steel factories in Tanzania were exposed to average noise of 92.0 dB(A), without using hearing protection, implying a high risk of developing hearing loss. Task and factory level determinants were identified in the furnace and the rolling mill sections of the plant, which can inform noise control in factories with similar characteristics.
Social Media’s Influence on Business-to-Business Sales Performance

Social media have become ubiquitous in many commerce circles and a global phenomenon the past several years. According to the Nielsen Company (2010), social media users worldwide grew nearly 30 percent in 2010, from 244 million to nearly 315 million users. Research from Gartner’s Consumer Technology and Markets group forecasted that global spending on social media would total $14.9 billion in 2012 (Gupta 2011). Social media, such as Twitter, have enabled customers to express their feelings regarding a product or service they have purchased. With this feedback, businesses can improve decisions on how to serve clients and create more informed solutions, thus increasing customer loyalty (Myron 2010). However, social media, also known as “social CRM” (customer relationship management), are still working their way into business-to-business (B2B) sales (Lager 2009). Results by ES Research Group (2009) show that only a small percentage of sales professionals use social media tools in their sales process.
Gaussian polynomials and content ideals

We prove that every regular Gaussian polynomial over a locally Noetherian ring has invertible content ideal. We do this by first proving that Gaussian polynomials over an approximately Gorenstein local ring have principal content ideal. We also show over locally Noetherian rings that a regular polynomial f of degree n is Gaussian if c(fg) = c(f)c(g) for polynomials g of degree at most n. Introduction A question which appears to have originated in the 1965 thesis of Kaplansky’s student Tsang asks whether over an integral domain the content of a nonzero Gaussian polynomial is an invertible ideal. Let R be a commutative ring. The content c(f) of a polynomial f ∈ R[t] is the ideal of R generated by the coefficients of f . A polynomial f(t) ∈ R[t] is Gaussian over R if for every polynomial g(t) ∈ R[t] we have c(fg) = c(f)c(g). A recent paper of Glaz and Vasconcelos [GV] on Gaussian polynomials and content ideals has motivated our interest in this topic. Glaz and Vasconcelos prove that a nonzero Gaussian polynomial over a normal Noetherian domain has invertible content ideal [GV, Theorem 4.4]. They also prove that a Gaussian polynomial over an integrally closed quasilocal domain (R,m) has principal content ideal provided the residue field R/m has characteristic p > 0 [GV, Theorem 3.1]. We are able to prove that rings that are locally approximately Gorenstein also have this property: a regular Gaussian polynomial over such a ring has invertible content ideal. See Corollary 2.7. Using this we prove that Gaussian polynomials over a locally Noetherian integral domain satisfy the conjecture of Tsang-Glaz-Vasconcelos (cf. Corollary 3.4). As an extension of the question from Tsang’s thesis, it is asked in [AK, Question 1.4] whether over an integral domain R a polynomial f(t) ∈ R[t] of degree n has an invertible content ideal if c(fg) = c(f)c(g) for all polynomials g(t) ∈ R[t] of degree at most n. We show in Corollary 3.4 that all Noetherian integral domains have this property. Let us say a polynomial f ∈ R[t] is Gaussian for polynomials of degree at most m if c(fg) = c(f)c(g) for all g ∈ R[t] with deg(g) ≤ m. If R is locally Noetherian and f(t) ∈ R[t] is of degree n and is regular, we show in Received by the editors October 18, 1995. 1991 Mathematics Subject Classification. Primary 13A15, 13B25, 13G05, 13H10. 1This question is explicitly given as Conjecture (1.1) in the paper of Sarah Glaz and Wolmer Vasconcelos [GV]. c ©1997 American Mathematical Society
Approximation Schemes for Maximum Weight Independent Set of Rectangles

In the Maximum Weight Independent Set of Rectangles (MWISR) problem we are given a set of n axis-parallel rectangles in the 2D-plane, and the goal is to select a maximum weight subset of pairwise non-overlapping rectangles. Due to many applications, e.g. in data mining, map labeling and admission control, the problem has received a lot of attention by various research communities. We present the first (1 + ε)-approximation algorithm for the MWISR problem with quasipolynomial running time 2poly(log n/ε). In contrast, the best known polynomial time approximation algorithms for the problem achieve superconstant approximation ratios of O(log log n) (unweighted case) and O(log n/log log n) (weighted case). Key to our results is a new geometric dynamic program which recursively subdivides the plane into polygons of bounded complexity. We provide the technical tools that are needed to analyze its performance. In particular, we present a method of partitioning the plane into small and simple areas such that the rectangles of an optimal solution are intersected in a very controlled manner. Together with a novel application of the weighted planar graph separator theorem due to Arora et al. [4] this allows us to upper bound our approximation ratio by 1 + ε. Our dynamic program is very general and we believe that it will be useful for other settings. In particular, we show that, when parametrized properly, it provides a polynomial time (1 + ε)-approximation for the special case of the MWISR problem when each rectangle is relatively large in at least one dimension. Key to this analysis is a method to tile the plane in order to approximately describe the topology of these rectangles in an optimal solution. This technique might be a useful insight to design better polynomial time approximation algorithms or even a PTAS for the MWISR problem. In particular, note that our results imply that the MWISR problem is not APX-hard, unless NP ⊆ DTIME(2polylog (n)).
A probe to the global color symmetry model

This paper has been withdrawn by the author due to the unsure solution to the Dyson-Schwinger equation.
Reliability and validity of the Korean version of the way-finding effectiveness scale for persons with dementia.

AIMS AND OBJECTIVES
To evaluate the psychometric properties of the Korean version of the Way-finding Effectiveness Scale (WES) for Korean persons with dementia (PWDs).


DESIGN
A descriptive, cross-sectional survey method was used.


METHODS
Data were collected with a non-probability sampling strategy using structured format face-to-face interviews. A convenience sample of 83 community-dwelling PWDs and their family caregivers were recruited. The participants were PWDs who were over 60 years of age, had been medically diagnosed with dementia or showed signs and symptoms of dementia, had a Mini Mental State Examination (MMSE) score of less than 24 of 30 and were independent in walking.


RESULTS
Internal consistency for the 29-item KWES was 0.93 and exceeded 0.70 for the four subscales (complex way-finding goals, CWG; analytic strategy, AS; global strategy, GS; and simple way-finding goals, SWG). The intercorrelations for total KWES and subscales demonstrated a high to moderate relationship ranging from 0.84 (total and CWG) to 0.24 (AS and SWG). Pearson correlations between each subscale scores of the KWES and K-MMSE demonstrated significant, moderate relationships ranging from 0.41 (CWG and K-MSE) to 0.28 (AS and K-MMSE). Differences in current and prior behaviour of KWES were significant for the total (t = -21.00, p < 0.001) and subscales (t = -28.33--9.33, p < 0.001).


CONCLUSION
Acceptable reliabilities and validities support the conclusion that the KWES is a valid and reliable instrument for examining way-finding effectiveness for Korean PWDs.


RELEVANCE TO CLINICAL PRACTICE
The KWES will contribute to the development of understanding of way-finding ability for community-dwelling PWDs in both research and clinical practices.
Alveolar ridge reconstruction with titanium meshes: 
A systematic review of the literature

Alveolar bone regeneration by means of titanium meshes is a widespread procedure, however to date, only few relevant studies were reported in literature concerning this technique. Consequently, the aim of the present systematic review was to analyze the reliability of the titanium mesh as a barrier, in conjunction with horizontal and vertical ridge reconstruction for implant placement purposes. A total of 17 articles complying with the inclusion and exclusion criteria were reviewed. Three outcome variables were defined: a) horizontal and vertical bone regeneration obtained, b) complication rate, defined as the percentage of membrane exposures and c) evaluation of implant survival, success and failure rate.In regards to the vertical regeneration the mean was 4.91 mm (range: 2.56 - 8.6), while a mean of 4.36 mm (range: 3.75 - 5.65) was calculated for horizontal reconstruction.Considering the exposure rate, a mean of 16.1% was found, nevertheless, implant placement were placed in almost all of the sites. A mean success rate of 89,9%, a mean survival rate of 100% and a failure rate of 0% emerged from the data evaluation. A meta-analysis could not be performed due to the heterogeneity of the data, however the final results were comparable with those reported in case of bone regeneration obtained through other types of non-resorbable membranes. An advantage in favour of the titanium mesh was found in terms of bone loss after exposure, as implant placement was not jeopardized in almost all of the cases. It could be deduced that titanium meshes represented a reliable solution for alveolar ridge reconstruction. The clinical studies currently available in literature have shown the predictability of this technique in both lateral and vertical bone regeneration.
Efficient Computer-User Interface in Electronic Mail Systems

Abstract This paper explores the question of improving the user-computer interface. The approach is one of observing and codifying various parameters that influence the efficiency of the interface in the context of electronic mail tasks. First, we observe “expert” and “regular” users of a mail system and identify the sources of efficiency. The data indicates that experts use a different, more specialized set of commands in performing standard mail tasks. While experts perform these tasks with fewer errors and more “completely”, it is not clear that they achieve this any faster than regular users. Recommendations for system design are made. In addition, errors made by subjects are codified. The major proportion of errors observed fall under syntactic and typographical categories. Implications for error recovery and prevention are discussed.
Changes in heart rate recovery after high-intensity training in well-trained cyclists

Heart rate recovery (HRR) after submaximal exercise improves after training. However, it is unknown if this also occurs in already well-trained cyclists. Therefore, 14 well-trained cyclists (VO2max 60.3 ± 7.2 ml kg−1 min−1; relative peak power output 5.2 ± 0.6 W kg−1) participated in a high-intensity training programme (eight sessions in 4 weeks). Before and after high-intensity training, performance was assessed with a peak power output test including respiratory gas analysis (VO2max) and a 40-km time trial. HRR was measured after every high-intensity training session and 40-km time trial. After the training period peak power output, expressed as W kg−1, improved by 4.7% (P = 0.000010) and 40-km time trial improved by 2.2% (P = 0.000007), whereas there was no change in VO2max (P = 0.066571). Both HRR after the high intensity training sessions (7 ± 6 beats; P = 0.001302) and HRR after the 40-km time trials (6 ± 3 beats; P = 0.023101) improved significantly after the training period. Good relationships were found between improvements in HRR40-km and improvements in peak power output (r = 0.73; P < 0.0001) and 40-km time trial time (r = 0.96; P < 0.0001). In conclusion, HRR is a sensitive marker which tracks changes in training status in already well-trained cyclists and has the potential to have an important role in monitoring and prescribing training.
Repaglinide/troglitazone combination therapy: improved glycemic control in type 2 diabetes.

OBJECTIVE
This multicenter open-label clinical trial compared the efficacy and safety of repaglinide/troglitazone combination therapy, repaglinide monotherapy, and troglitazone monotherapy in type 2 diabetes that had been inadequately controlled by sulfonylureas, acarbose, or metformin alone.


RESEARCH DESIGN AND METHODS
Patients with type 2 diabetes (n = 256) who had inadequate glycemic control (HbA1c > or =7.0%) during previous monotherapy were randomly assigned to receive repaglinide (0.5-4.0 mg at meals), troglitazone (200-600 mg once daily), or a combination of repaglinide (1-4 mg at meals) and troglitazone (200-600 mg once daily). After a 4-6 week washout period, the trial assessed 22 weeks of treatment: 3 weeks (weeks 0-2) of forced titration, 11 weeks of fixed-dose treatment (weeks 3-13), and 8 weeks (weeks 14-21) of titration to maximum dose. Changes in HbA1c and fasting plasma glucose (FPG) values were measured.


RESULTS
The combination therapy showed a significant reduction in mean HbA1c values (-1.7%) that was greater than with either type of monotherapy Repaglinide monotherapy resulted in a reduction of HbA1c values that was significantly greater than troglitazone (-0.8 vs. -0.4%) (P < 0.05). Combination therapy was more effective in reducing FPG values (-80 mg/dl) than either repaglinide (-43 mg/dl) or troglitazone (-46 mg/dl) monotherapies. Adverse events were similar in all groups.


CONCLUSIONS
Combination therapy with repaglinide and troglitazone leads to better glycemic control than monotherapy with either agent alone. Repaglinide monotherapy was more effective in lowering HbA1c levels than troglitazone monotherapy Repaglinide/troglitazone combination therapy was effective and did not show unexpected adverse events.
A Study on A Context Clustering Technique for Average Voice Models

This paper describes a new context clustering technique for average voice model, which is a set of speaker independent speech synthesis units. In the technique, we first train speaker dependent models using multi-speaker speech database, and then construct a decision tree common to these speaker dependent models for context clustering. When a node of the decision tree is split, only the context related questions which are applicable to all speaker dependent models are adopted. As a result, every node of the decision tree always has training data of all speakers. After construction of the decision tree, all speaker dependent models are clustered using the common decision tree and a speaker independent model, i.e., an average voice model is obtained by combining speaker dependent models. From the results of subjective tests, we show that the average voice models trained using the proposed technique can generate more natural sounding speech than the conventional average voice models. key words: decision tree, context clustering, average voice model, HMM-based speech synthesis, speaker independent model
Dear prudence. Interview by Sophia Häfner.

Chicken chicken chicken: chicken chicken. This is actually no major typing error but well and truly the title of both a publication in the 2006 Annals of Improbable Research [2] and a homonymous talk at the 2007 AAAS conference by the software engineer Doug Zongker, composed of totally serious looking texts, graphs and diagrams e based exclusively on a vocabulary restricted to the common name of Gallus gallus domesticus. Apart from having caused the open-plan hilarity of the scientific public, chicken and more generally fowl also happen to be the main reservoir and evolutionary playground for influenza A viruses that occasionally jump over to humans and even more occasionally cause a media e centered commotion. Indeed, manifold combinations of hemagglutinin H1 to H16 and neuraminidase N1 to N9, the two surface proteins used to subtype the virus, are all found in wild water birds and at least seven of them have made it into humans until now [3]. Interestingly, that renders birds apparently better at handing down infectious agents to humans than those closest relatives, African apes, who managed to pass “only” two diseases on to us. Admittedly, the agents in question are Plasmodium falciparum and HIV-1, but considering the broad range of available pathogens, the number remains low [4]. It remains nevertheless ambiguous if the simian pathogens are untalented or rather lacked the opportunities of their winged relatives, spreading their gatecrashers through direct contact on live poultry markets [3]. The latest edition of the series is H7N9, which caused its first human victims in February 2013 [5,6], after about two years of patching up starting from H7N3, H9N9 and a preliminary version of H7N9 [7], with the involuntary participation of ducks, bramblings and other migratory birds as vectors [6]. Above all praised as a victory of the rapid and coordinated reaction of the Chinese health instances and the fast and efficient sharing of information at the international level [4], from he media coverage point of view, things have been remarkably calm around H7N9 lately, despite the fact that the season-related second outbreak in China at the end of this winter caused way more fatalities than the one in 2013 [8]. Papers were busily