Weak Results Research Articles

Density estimates for the zeros of the Beurling ζ function in the critical strip

We prove three results on the density resp. local density and clustering of zeros of the Beurling zeta function $\zeta(s)$ close to the one-line $\sigma:=\Re s=1$. The analysis here brings about some news, sometimes even for the classical case of the Riemann zeta function. Theorem 4 provides a zero density estimate, which is a complement to known results for the Selberg class. Note that density results for the Selberg class rely on use of the functional equation of $\zeta$, which we do not assume in the Beurling context. In Theorem 5 we deduce a variant of a well-known theorem of Tur\'an, extending its range of validity even for rectangles of height only $h=2$. In Theorem 6 we will extend a zero clustering result of Ramachandra from the Riemann zeta case. A weaker result -- which, on the other hand, is a strong sharpening of the average result from the classic book \cite{Mont} of Montgomery -- was worked out by Diamond, Montgomery and Vorhauer. Here we show that the obscure technicalities of the Ramachandra paper (like a polynomial with coefficients like $10^8$) can be gotten rid of, providing a more transparent proof of the validity of this clustering phenomenon.

Revisiting managerial “style”: The replicability and falsifiability of manager fixed effects for firm policies

AbstractResearch SummaryWe attempt to replicate Bertrand and Schoar (2003), who used manager fixed effects to provide evidence for managerial “style” as measured by metrics such as leverage, R&D spending, and Tobin's Q. We find that the statistical and economic significance of manager fixed effects is generally lower in our results than in theirs. This discrepancy motivated us to conduct placebo tests in which we randomize managers' spells at their firms. The results with the randomized data are generally as strong as those with the real data, suggesting (a) that the apparent explanatory power of manager fixed effects may be largely a statistical artifact and (b) that managerial “style” may manifest itself in more complex ways than can be ascertained from examining financial statement metrics.Managerial SummaryAn influential body of research uses large datasets of firm financial information to study whether individual top managers have a “style” as measured by metrics such as leverage and R&D spending. We attempt to replicate a leading paper in this body of research but obtain quite different, usually weaker results. We also try repeating the analysis using artificial datasets where managers are randomly assigned to firms other than those at which they really worked. These randomized datasets produce results that are generally as strong as those with the real data. The implications are that the statistical methodology used in this body of research may be generating spurious results and that managerial “style” may be too complex to ascertain from examining financial statement metrics.

Estimation of Solar Radiation on a PV Panel Surface with an Optimal Tilt Angle Using Electric Charged Particles Optimization

Solar energy is a promising renewable energy source that can fulfill the world’s current and future energy needs. The angle at which a photovoltaic (PV) panel faces the horizon determines the incidence of solar radiation. The incident solar radiation on PV panels could be optimized by adjusting their tilt angles and increasing the power output of the PV array. In this study, solar energy model-based research was conducted in the Saudi Arabian cities of Dhahran and Makkah. This study investigated the performance of a 1 kW monocrystalline silicon PV array in these cities. Analyzing the optimal tilt angle for efficiency and performance improvement of the PV panel is challenging. The optimal tilt angle is determined by combining the data of the Sun’s diffuse, direct radiation and the global horizontal Sun radiation. This research examined the four empirical models by applying the electric charged particle optimization (ECPO) algorithm to estimate the solar radiation on sloped surfaces. The model’s results were compared to the global horizontal solar radiation based on the daily mean solar radiation value in these cities. The Hay–Davies–Klucher–Reindel model presented the maximum amount of tilted surface solar radiation in the year and at different periods. In contrast, the Badescu model exhibited the weakest results of all the isotropic and anisotropic models. Finally, using the ECPO algorithm, all models indicated that tilted surfaces (IT) received more solar radiation than horizontal surfaces (Ig).

Hamilton’s rule in economic decision-making

Hamilton’s rule [W. D. Hamilton, Am. Nat. 97, 354–356 (1963); W. D. Hamilton, J. Theor. Biol. 7, 17–52 (1964)] quantifies the central evolutionary ideas of inclusive fitness and kin selection into a simple algebraic relationship. Evidence consistent with Hamilton’s rule is found in many animal species. A drawback of investigating Hamilton’s rule in these species is that one can estimate whether a given behavior is consistent with the rule, but a direct examination of the exact cutoff for altruistic behavior predicted by Hamilton is almost impossible. However, to the degree that economic resources confer survival benefits in modern society, Hamilton’s rule may be applicable to economic decision-making, in which case techniques from experimental economics offer a way to determine this cutoff. We employ these techniques to examine whether Hamilton’s rule holds in human decision-making, by measuring the dependence between an experimental subject’s maximal willingness to pay for a gift of $50 to be given to someone else and the genetic relatedness of the subject to the gift’s recipient. We find good agreement with the predictions of Hamilton’s rule. Moreover, regression analysis of the willingness to pay versus genetic relatedness, the number of years living in the same residence, age, and sex shows that almost all the variation is explained by genetic relatedness. Similar but weaker results are obtained from hypothetical questions regarding the maximal risk to her own life that the subject is willing to take in order to save the recipient’s life.

ON A PROPERNESS OF THE HILBERT EIGENVARIETY AT INTEGRAL WEIGHTS: THE CASE OF QUADRATIC RESIDUE FIELDS

AbstractLetpbe a rational prime. LetFbe a totally real number field such thatFis unramified overpand the residue degree of any prime ideal ofFdividingpis$\leq 2$. In this paper, we show that the eigenvariety for$\mathrm {Res}_{F/\mathbb {Q}}(\mathit {GL}_{2})$, constructed by Andreatta, Iovita, and Pilloni, is proper at integral weights for$p\geq 3$. We also prove a weaker result for$p=2$.

Profinite groups with few conjugacy classes of 𝑝-elements

It is proved that a profinite groupGGhas fewer than2ℵ02^{\aleph _0}conjugacy classes ofpp-elements for an odd primeppif and only if itspp-Sylowpp-subgroups are finite. (Here, by app-element one understands an element that either haspp-power order or topologically generates a group isomorphic toZp\mathbb {Z}_p.) A weaker result is proved forp=2p=2.

Business Digital Maturity in Europe and Its Implication for Open Innovation

This paper presents the results of a study aimed at assessing the level of business digital maturity in Europe and at analyzing similarities between companies in terms of implemented Industry 4.0 technologies. The digital transformation of production and service enterprises has become a common direction of development for all economic sectors. The very idea of Industry 4.0 has become synonymous with innovation and is the basis for business development. The role and importance of these transformations are also recognized by the EU which has been promoting and supporting the development of an innovative digital economy for many years. However, individual EU countries differ in terms of digital business maturity due to the implementation of Industry 4.0 technology. The article addresses this problem by presenting the results of a comprehensive study of the implementation of Industry 4.0 digital technologies in enterprises in the EU-27 countries and by assessing similarities between these countries in terms of these technologies. The similarity analysis was carried out using the k-means method. The Gini coefficient and Lorenz curves were utilized to determine the unevenness of the implementation of these technologies in individual countries, and the Weighted Aggregated Sum Product Assessment method was used to assess the level of digital maturity. The research was based on eight selected determinants (indicators) that characterize the most important technologies related to Industry 4.0. The results showed high diversity among EU countries in terms of digital maturity. Scandinavian countries (Finland and Denmark) and Malta were found to be leaders in this area, while the weakest results were reported for Greece, Romania, Bulgaria, Hungary, and Latvia. The findings provide a lot of new information about the current state of development of the digital economy in EU countries, which should be used in both the development and implementation of new solutions related to economic digitalization policy in this region.

Relations between reading skill level in fifth grade and functional language skills at toddler age

ABSTRACT This retrospective study, undertaken in Norway, examines how reading skills level in 851 fifth graders are related to how the children used their language skills in play and everyday activities as toddlers. Data were collected with the Norwegian National Reading Test and through structured observations by staff in Early Childhood Education institutions using the TRAS (Early Registration of Language Skills) instrument. Children with low reading skills had lower language skills than the group with high reading skills for both TRAS total and the different TRAS sections; effect sizes varied from small to moderate. The group with moderate reading skills had better results for TRAS total than the group with low reading skills but weaker results than the group with high reading skills. In the TRAS sections, whether the moderate skills group differed from the other groups varied. The results imply the need for early intervention to start at toddler age.

On the existence and asymptotic behavior of solutions of half-linear ordinary differential equations

On the existence and asymptotic behavior of solutions of half-linear ordinary differential equations

Functional capacity and risk of frailty syndrome in 85-year-old and older women living in nursing homes in Poland

Maintaining sufficient physical fitness to prevent any limitations in performing activities of daily living and to be functionally independent is of great importance for both longevity and quality of life in older adults. Aim of the study was to evaluate functional physical fitness of women aged 85 years and older, residents of nursing homes, in the Polish population and to assess the risk of frailty syndrome. The study involved 17 women aged 85 years or older, residents of nursing homes in the Lower Silesian voivodeship. The Senior Fitness Test was used to assess functional fitness. The results of functional fitness tests were related to the standards for the elderly population in Poland and to the reference standards for maintaining independence. In addition, hand grip strength level was measured using a hand dynamometer, height and weight were measured, and BMI was calculated. 15-item version of the Geriatric Depression Scale was used to assess the level of depression. We used 3 of the 5 proposed criteria from the Cardiovascular Health Study Frailty Index to assess the presence of frailty syndrome: gait speed, level of hand grip strength, and the presence of depression. The results of the Senior Fitness Test demonstrate the low level of functional fitness of female nursing home residents. A large percentage of the women surveyed are below the standard values developed for Polish seniors. The weakest results were in the timed up and go test, with more than 94% of the women tested falling outside the standard ranges. The mean results of all samples do not meet the developed reference standards for maintaining independence. No non-frail person was found among the study participants and the vast majority were at risk for frailty syndrome. Most of the studied women do not meet functional fitness standards developed for the Polish population, as well as reference standards for maintaining independence. Nursing home residents over the age of 85 are at risk for frailty syndrome.

Comparison of remote and in-person tutorials of color appearance phenomena

Accurately describing the effect of lighting on color appearance phenomena is critical for color science education. While it is ideal to conduct in-person tutorials to demonstrate the color appearance fundamentals, laboratory tutorials have been limited due to COVID-19. The limitation of in-person gatherings and the increase popularity of remote teaching help evoke alternative methods to demonstrate color appearance phenomena. Here, a remote tutorial method is described, and results are compared to in-person tutorials. While the remote tutorial had weaker result in representing observers' color experience compared to the in-person lab tutorial, remote demonstrations can be used to demonstrate and discuss the limitations of color imaging, and the difference between the human visual system and digital imaging systems.

Simultaneous monitoring of the values of CD, Crosstalk and OSNR phenomena in the physical layer of the optical network using CNN

The aim of the research was to explore the possibilities of using the Asynchronous Delay Tap Sampling (ADTS) and Convolutional Neural Network (CNN) methods to monitor the simultaneously occurring phenomena in the physical layer of the optical network. The ADTS method was used to create a data sets showing the combination of Chromatic Dispersion (CD), Crosstalk and Optical to Signal Noise Ratio (OSNR) as optical disturbances in graphic form. Data were generated for 10 GB/s, Non-return-to-zero On–off keying (NRZ-OOK) and Differential Phase Shift Keying (DPSK) modulation and bit delays: 1 bit, 0.5 bit and 0.25 bit. A total of 6 data sets of 62,000 images each were obtained. The learning process was carried out for the number of epochs 50 and 1000. From the obtained learning results of the network, models with the best R^{2} matching factor were selected. The learned models were further used to study the recognition of three phenomena simultaneously. The tests were carried out on sets of 2500 images in a combination of interference in the following ranges: 400–1600 ps/nm for CD and 10–30 dB for Crosstalk and OSNR. Very good results were obtained for recognizing simultaneously occurring phenomena using models learned up to 1000 epoch. Accuracy of over 99% was obtained for CD and Crosstalk for both modulations. In the case of the OSNR phenomenon, slightly weaker results were obtained above 96% in most cases. For models taught up to 50 epoch, very good results were obtained for the CD phenomenon (over 99%). For Crosstalk weaker results for OOK modulation were obtained. Poor results were obtained for the OSNR phenomenon, where recognition accuracy ranged from 50 to 80%, depending on the type of modulation and bit delay. Based on the conducted research, it was established that the use of ADTS and CNN methods enables monitoring of simultaneously occurring CD, Crosstalk and OSNR interference in the physical layer of the optical network, while maintaining the requirements for Optical Performance Monitoring systems. These requirements are met for network models learned up to 1000 epoch.

Satellite rainfall bias assessment for crop growth simulation – A case study of maize growth in Kenya

In this research, the performance of satellite rainfall estimates (SREs) for crop growth simulation was investigated. Rainfall products selected were CHIRPS 2.0, CMORPH 1.0, MSWEP 2.2, and RFE 2.0. In-situ rainfall from 20 stations within the Lake Victoria basin in Kenya served as reference. Rainfall products were evaluated for onset days, rainfall depths, dry spells, and rainfall occurrence for four crop growth stages. Assessment was on a daily time step for the period 2012–2018 and on a point-to-pixel basis. Results showed that SREs exhibit large variation in timing of rainfall arrival. SREs exhibited largest interannual and spatial spreads in representing dry spell length during the flowering stage with CMORPH and CHIRPS showing best and weakest results, respectively. Bias of SREs in representing dry spells was smaller during early growth stages. Detecting rainfall occurrence by the SREs weakened as the growing season progressed. MSWEP, followed by RFE2, produced the best results in detecting rainfall events, while falsely detected rainfall was frequent in CHIRPS, particularly in later growth stages. SREs generally performed better during a wet than a dry growing season. SREs indicated less bias in rainfall depths during the early stages of crop growth but deteriorated at later stages. MSWEP and CMORPH exhibited the least and highest interannual spread in relative bias, respectively. In associating biases to severe and extreme water stress, based on crop water requirement satisfaction index, effects were more prevailing in the ripening than flowering stages. Findings of this study suggest that SREs can serve as input to crop growth modelling, but validation of SREs with rain gauge observed counterparts is essential.

ЮНВТО Всемирная туристская Барометр, и статистическое приложение Обновленная информация, ИСентябрь 2021 года

International tourism shows slight recovery in June and July 2021 driven by vaccinations and border reopening International tourist arrivals (overnight visitors) in the first seven months of 2021 were 40% below the levels of 2020, and still 80% down when compared to the same period of pre-pandemic year 2019. After a weak start of the year, international tourism saw a modest improvement during the months of June and July 2021. The small improvement in June and July was underpinned by the reopening of many destinations to international travel, mostly in Europe and the Americas. The relaxation of travel restrictions to vaccinated travellers, coupled with progress made in the roll-out of COVID-19 vaccines, contributed to ease travel restrictions, lift consumer confidence and gradually restore safe mobility in Europe and other parts of the world. Small islands in the Caribbean, Africa, and Asia and the Pacific, together with a few small European destinations recorded the best performance in June and July, with arrivals coming close to, or sometimes exceeding pre-pandemic levels. July (-67%) saw comparatively better performance than June (-77%), making it the best month so far since April 2020. Asia and the Pacific continued to suffer the weakest results in January-July 2021, with a 95% drop in international arrivals compared to the same period in 2019. The Middle East (-82%) recorded the second largest decline, followed by Europe and Africa (both -77%). The Americas (-68%) saw a comparatively smaller decrease. Although destinations continued to report very weak international tourism revenues in the first seven months of 2021, several countries recorded a modest improvement in the months of June and July, and some even surpassed the earnings of 2019. The same is true for outbound travel. Among the larger source markets, France (-35% over 2019) and the United States (-49%) saw a small rebound in expenditure in July. Despite the relative improvement over the low levels of 2020, international tourism remained well below 2019 levels. This is also reflected in the evaluation made by the UNWTO Panel of Experts in the September survey, showing mixed results for the period May-August 2021. Looking ahead, most experts continue to expect a rebound in 2022, driven by unleashed pent-up demand, mostly during the second and third quarter of that year. Nearly one-third of respondents expect a potential rebound in 2023. Almost half of all experts continue to see a return of international arrivals to 2019 levels in 2024 or later.

Baromètre OMT du tourisme mondial et annexe statistique, septembre 2021

International tourism shows slight recovery in June and July 2021 driven by vaccinations and border reopening International tourist arrivals (overnight visitors) in the first seven months of 2021 were 40% below the levels of 2020, and still 80% down when compared to the same period of pre-pandemic year 2019. After a weak start of the year, international tourism saw a modest improvement during the months of June and July 2021. The small improvement in June and July was underpinned by the reopening of many destinations to international travel, mostly in Europe and the Americas. The relaxation of travel restrictions to vaccinated travellers, coupled with progress made in the roll-out of COVID-19 vaccines, contributed to ease travel restrictions, lift consumer confidence and gradually restore safe mobility in Europe and other parts of the world. Small islands in the Caribbean, Africa, and Asia and the Pacific, together with a few small European destinations recorded the best performance in June and July, with arrivals coming close to, or sometimes exceeding pre-pandemic levels. July (-67%) saw comparatively better performance than June (-77%), making it the best month so far since April 2020. Asia and the Pacific continued to suffer the weakest results in January-July 2021, with a 95% drop in international arrivals compared to the same period in 2019. The Middle East (-82%) recorded the second largest decline, followed by Europe and Africa (both -77%). The Americas (-68%) saw a comparatively smaller decrease. Although destinations continued to report very weak international tourism revenues in the first seven months of 2021, several countries recorded a modest improvement in the months of June and July, and some even surpassed the earnings of 2019. The same is true for outbound travel. Among the larger source markets, France (-35% over 2019) and the United States (-49%) saw a small rebound in expenditure in July. Despite the relative improvement over the low levels of 2020, international tourism remained well below 2019 levels. This is also reflected in the evaluation made by the UNWTO Panel of Experts in the September survey, showing mixed results for the period May-August 2021. Looking ahead, most experts continue to expect a rebound in 2022, driven by unleashed pent-up demand, mostly during the second and third quarter of that year. Nearly one-third of respondents expect a potential rebound in 2023. Almost half of all experts continue to see a return of international arrivals to 2019 levels in 2024 or later.

On Effectively Indiscernible Projective Sets and the Leibniz-Mycielski Axiom

Examples of effectively indiscernible projective sets of real numbers in various models of set theory are presented. We prove that it is true, in Miller and Laver generic extensions of the constructible universe, that there exists a lightface Π21 equivalence relation on the set of all nonconstructible reals, having exactly two equivalence classes, neither one of which is ordinal definable, and therefore the classes are OD-indiscernible. A similar but somewhat weaker result is obtained for Silver extensions. The other main result is that for any n, starting with 2, the existence of a pair of countable disjoint OD-indiscernible sets, whose associated equivalence relation belongs to lightface Πn1, does not imply the existence of such a pair with the associated relation in Σn1 or in a lower class.

Therapeutic Opportunities for Food Supplements in Neurodegenerative Disease and Depression.

Emerging evidence is showing nutrition as a crucial factor in the high prevalence and incidence of neurodegenerative mental disorders. Preventive interventions on neuroinflammation seem to be able to interfere with neurodegeneration. Supplementation of essential nutrients, such as long-chain-polyunsaturated fatty acids, vitamin E and mineral elements, may minimize inflammation, enhancing antioxidative defense, and lowering the risk and incidence of age-related diseases, such as cardiovascular diseases and neurodegenerative diseases. This manuscript reviews the current evidence on the role of neuroinflammation in the pathophysiology of neurodegenerative and mental disorders, and preventive strategies for food supplementation in these neuropsychiatric diseases. Dietary supplementation-based strategies have been demonstrated to be effective in subjects with mild cognitive impairment, while weaker results have been obtained in patients with advance neurodegenerative disease. Adjunctive supplementation has also been demonstrated to improve depression, this being of marked benefit considering the comorbidity between cognitive impairment/dementia and depression. Further research is needed to improve the prescriptive precision of supplementation in patients, and to better understand potential interactions with clinical and pharmacokinetic factors.

Generalized Notions of Sparsity and Restricted Isometry Property. Part II: Applications

Restricted isometry property (RIP) provides a near isometric map for sparse signals. RIP of structured random matrices has played a key role for dimensionality reduction and recovery from compressive measurements. In a companion paper, we have developed a unified theory for RIP of group structured measurement operators on generalized sparsity models. The implication of the extended result will be further discussed in this paper in terms of its pros and cons over the conventional theory. We first show that the extended RIP theory enables the optimization of sample complexity over various relaxations of the canonical sparsity model. Meanwhile, the generalized sparsity model is no longer described as a union of subspaces. Thus the sparsity level is not sub-additive. This incurs that RIP of double the sparsity level does not imply RIP on the Minkowski difference of the sparsity model with itself, which is crucial for dimensionality reduction. We show that a group structured measurement operator provides an RIP-like property with additive distortion for non-sub-additive models. This weaker result can be useful for applications like locality-sensitive hashing. Moreover, we also present that the group structured measurements with random sign enables near isometric sketching on any set similar to the Gaussian measurements. Lastly, an extension of theory to infinite dimension is derived and illustrated over selected examples given by Lebesgue measure of support and Sobolev seminorms.

Comparative analysis of selected business indicators of state forest companies

A company that handles natural resources such as forests is a complex economic entity. In addition to economic performance at annual level, the biological component of sustainable forest management should also be considered. It is therefore extremely important to achieve efficient business performance. Financial analysis is a process of determining important business and financial characteristics of a company from accounting data. It is characterized by a wide use of financial reports and various financial indicators - key figures. The paper presents business indicators of the main state-owned forest companies in selected countries of South East Europe (Croatia, Slovenia, Serbia, Bosnia and Herzegovina, and North Macedonia) using the method of comparative analysis based on financial reports (such as balance sheet and income statement). In countries where there are more than one state-owned forest companies, they were selected according to their importance for forest management and business results (share of forests, number of employees, profit and annual felling). The research results show the revenue and expenditure of the selected companies and profitability indicators such as return on equity (ROE) and return on assets (ROA). According to the annual business reports for 2017 and 2018, the company Croatian Forests Ltd. has the highest number of employees (7787 in 2018). The highest ratio ROA (32.17) and ROE (39.82) were achieved in the Slovenian state forestry company in 2017, which was founded in 2016. For 2018, the best results are achieved in the Slovenian Forest Company (SiDG), while the weakest results are achieved in the State Forest Company in North Macedonia. The profit per employee decreased in 2018 for most companies, but most significantly in North Macedonia, where it was four times lower. On the basis of the comparative analysis presented, all companies have a positive cost-benefit ratio, but long-term planning of forest management should follow biological and economic regulations to be competitive on the free market.

Maghemite nanoparticles coated by methacrylamide-based polymer for magnetic particle imaging

A wise selection of tracers is critical for magnetic particle imaging (MPI). Most of the current tracers are based on superparamagnetic iron oxide nanoparticles (SPIONs) with a suitable coating. We prepared maghemite cores (γ-Fe2O3) by coprecipitation of Fe(II) and Fe(III) salts with ammonium hydroxide followed by oxidation with hydrogen peroxide and stabilization as an anionic (γ-Fe2O3⊖) or cationic colloid (γ-Fe2O3⨁). The cores were coated by poly(N-(2-hydroxypropyl)methacrylamide)-co-N-[2-(hydroxyamino)-2-oxo-ethyl]-2-methyl-prop-2-enamide. The particles were characterized by dynamic light scattering, transmission electron microscopy, X-ray diffraction, Mössbauer spectroscopy, tested in vitro in a field-free point MPI scanner, and compared to nanoparticles prepared by oxidation with sodium hypochlorite and to the commercially available Resovist®. The cores had an average diameter of 8.0 nm (γ-Fe2O3⨁) and 8.7 nm (γ-Fe2O3⊖); the hydrodynamic diameter was 88 nm. Zeta potential values for both positively charged (+52 mV) and negatively charged particles (–60 mV) provided for good colloidal stabilization. Spinel structure of maghemite was confirmed by Mössbauer spectroscopy. The uncoated γ-Fe2O3⨁ particles yielded an MPI signal lower (by 16 %) than Resovist; the coated ones reached 88 % of the Resovist signal. Anionic γ-Fe2O3⊖ particles reached a higher (uncoated particles, by 15 %) or comparable (coated ones) signal relative to Resovist with a substantially lower signal dispersion. Control particles prepared by oxidation with sodium hypochlorite scored the weakest results. To conclude, a suitable size, narrow size distribution, and colloidal stability predispose the synthetized particles for use as a tracer for MPI. The anionic particles provided a higher signal with a lower dispersion than commercial tracers.