Apparent Path Research Articles

The small-world effect for interferometer networks

Complex network theory has focused on properties of networks with real-valued edge weights. However, in signal transfer networks, such as those representing the transfer of light across an interferometer, complex-valued edge weights are needed to represent the manipulation of the signal in both magnitude and phase. These complex-valued edge weights introduce interference into the signal transfer, but it is unknown how such interference affects network properties such as small-worldness. To address this gap, we have introduced a small-world interferometer network model with complex-valued edge weights and generalized existing network measures to define the interferometric clustering coefficient, the apparent path length, and the interferometric small-world coefficient. Using high-performance computing resources, we generated a large set of small-world interferometers over a wide range of parameters in system size, nearest-neighbor count, and edge-weight phase and computed their interferometric network measures. We found that the interferometric small-world coefficient depends significantly on the amount of phase on complex-valued edge weights: for small edge-weight phases, constructive interference led to a higher interferometric small-world coefficient; while larger edge-weight phases induced destructive interference which led to a lower interferometric small-world coefficient. Thus, for the small-world interferometer model, interferometric measures are necessary to capture the effect of interference on signal transfer. This model is an example of the type of problem that necessitates interferometric measures, and applies to any wave-based network including quantum networks.

The Taguelft syncline (Moroccan Central High Atlas) an example of extension-related mini-basin evidenced by paleomagnetic data

The purpose of this work is to use paleomagnetic data to determine the tectonic evolution of the inverted High Atlas basin in the area of the Taguelft syncline. This syncline shows two well defined rock types of Jurassic age: marly limestones and red beds, and therefore provides the opportunity of comparing paleomagnetic results from rocks with different magnetic mineralogy. Forty-three sites, in an area of 250 km2 were the subject of a paleomagnetic and rock magnetic study. Both lithologies display a stable interfolding remagnetization, alternatively carried by magnetite in marly-limestones and hematite in red beds. The small circle intersections (SCI) method applied separately to the mean directions of the two rock types indicate a synchronous record of remagnetization, that can be dated as Mid-Cretaceous (100 Ma) by comparing the direction (SCI) with the expected directions obtained from the Global Apparent Wander Path in African coordinates. Small circle techniques were used to reconstruct the syncline geometry at the remagnetization time. Paleodips quantification reveals that this area behaved as an extension-related mini-basin, with strong control by salt migration, before and during the sedimentation of Bathonian red beds.

Force illusion induced by visual illusion: Illusory curve in cursor path is interpreted as unintended force.

Discrepancies between expected and actual visual outcomes of motor action can produce an illusory sensation of unintended force. In the present study, we addressed whether the force illusion could be induced even when the discrepancy was brought about by the illusory appearance of the actual outcome. Specifically, the apparent path of a cursor controlled by the participants was modulated by the direction of noise motion presented inside the cursor. We showed that a greater noise motion inside the cursor caused a greater apparent curve of the cursor path and, also, higher rating scores for an unintended force. We also found that the unintended force was influenced strongly by the visibility of the cursor, suggesting that the apparent curve of the cursor path was a more important factor in generating the unintended force than the noise motion itself inside the cursor. Our results suggest that the illusory force, which is mediated by cross-modal mechanisms susceptible to visual illusion, can be exploited in extended reality systems as a novel technique for giving users a sensation of force.

The Influence of Enterprise Investment Behavior on the Cyberspace Connection of Coastal Cities: Empirical Evidence from China

In the era of globalization and informatization, urban development patterns need to be generated with the network structure between cities taken into account. The urban network constructed based on enterprise connections has recently garnered substantial research interest. However, most of the research efforts have been channeled toward constructing urban networks via the relationship between headquarters and branches within enterprises, with little attention paid to urban networks through the lens of financial connections between enterprises. In this study, the cross-regional investment data of enterprises are used to establish an urban network, revealing its spatial distribution and evolutionary dynamics. The main conclusions are as follows. First, corporate investment behavior somewhat fuels the structure and direction of the urban network. The correlation degree of the network is significantly enhanced, and the network relationship has an apparent economic focus, resource focus, and path dependence characteristics. Spatial connections show the dual characteristics of large-scale preferential connections (outside the region) and small- and medium-scale adjacent connections (inside the region). Second, from 2006 to 2016, cross-regional investment was further concentrated in core cities and hotspot cities, and the flow of funds between regions also changed from being within-region to primarily being inter-regional. However, the dominant role of traditional core cities or hotspot cities such as Shanghai, Shenzhen, Guangzhou, Hangzhou, and Ningbo are apparent, resulting in a network structure in line with a core–periphery model. Finally, compared with other dimensions of urban networks, in addition to the effective play of the investment function of the core cities or the hotspot cities, some small- and medium-sized cities with rich resources also play an important connecting role in the network. These research results provide a decision-making basis for urban spatial structure, functional integration, and collaborative planning; furthermore, they promote the research on urban networks based on actual economic activities among enterprises.

The challenges of the female executive career

This work has aimed to assimilate the obstacles faced by women to achieve success in their professional careers. To achieve this aim, at first, a literature review was carried out with the themes of women working in medium and large companies, female leadership, gender inequality, the division between personal and professional life, and double working hours, enabling the bases of theoretical frameworks for research. Then, the empirical data were gathered from qualitative research through interviews with a semi-structured script. Based on these data, a content analysis was carried out based on the theoretical review and the results of the interviews, and, subsequently, an interpretative assessment based on the reports of the interviewees. Through this analysis, traits that interfere with and assist the female executive career were observed. Behavioral factors linked to organizational guidelines (e.g., machismo) were identified, and that there is still an apparent arduous path for women to reach higher positions in organizations. Another issue encountered is the issue of double working day.

The Effect of Time Resolution on Apparent Transition Path Times Observed in Single-Molecule Studies of Biomolecules.

Single-molecule experiments have now achieved a time resolution allowing observation of transition paths, the brief trajectory segments where the molecule undergoing an unfolding or folding transition enters the energetically or entropically unfavorable barrier region from the folded/unfolded side and exits to the unfolded/folded side, thereby completing the transition. This resolution, however, is yet insufficient to identify the precise entrance/exit events that mark the beginning and the end of a transition path: the nature of the diffusive dynamics is such that a molecular trajectory will recross the boundary between the barrier region and the folded/unfolded state, multiple times, at a time scale much shorter than that of the typical experimental resolution. Here we use theory and Brownian dynamics simulations to show that, as a result of such recrossings, the apparent transition path times are generally longer than the true ones. We quantify this effect using a simple model where the observed dynamics is a moving average of the true dynamics and discuss experimental implications of our results.

Introduction

Introduction

Latitudinal land–sea distributions and global surface albedo since the Cretaceous

We estimate global surface albedo from the areal proportion of land to sea in climatically-significant latitudinal belts at ten million-year intervals for the Late Cretaceous and Cenozoic (120 million years ago to Present) using modern plate tectonic reconstructions and a composite apparent polar path designed to minimize known biases in the determination of paleolatitude. We find that global surface albedo stayed almost constant until it shifted 30% higher to the modern value of around 0.15 with the inception of the Late Cenozoic Ice Age 34 million years ago, reflecting polar ice-albedo amplification of global cooling resulting from the reduction of greenhouse gases below a critical threshold, most probably as the culmination of enhanced CO 2 weathering consumption of continental mafic rocks in the tropical humid belt. The contribution from cloud cover toward a planetary albedo is unclear in the absence of measurable proxies but might eventually be gauged from the role cloudiness evidently plays in maintaining radiative balance with the increasing land bias between northern and southern hemispheres over the Cenozoic. • Changes in land–sea area were small in equatorial and polar climate belts from 120 Ma • Land area decreased in temperate belts and increased in subtropical arid belts • Global surface albedo was low from 120 to 40 Ma and shifted to modern value by 30 Ma • Increase in surface albedo due to polar ice cover with Late Cenozoic Ice Age at 34 Ma • Ice age reflects polar amplification of global cooling triggered by drawdown of CO 2

Strategic development of third-party logistics providers (TPLs): “Going under the floor” or “raising the roof”?

Contemporary (third-party logistics providers) TPLs are in danger of being stuck in the middle, unable to perform customer adaptation as well as before and unable to achieve sufficient economies of scale. This conceptual paper aims to explore challenges facing the strategic development of TPLs within a context of increased digitalization, e-commerce and servitization.There are two apparent strategic paths. Under circumstances of strong price pressure, there is demand for standardized TPL services offering simplicity, minimalism and functionality based on digitalization, e-commerce and servitization. Alternatively, with market developments responsive to supply chain complexity, digitalization, e-commerce and servitization enable development towards innovation and change.We conclude that these developments do not invalidate existing frameworks for TPL strategies but contribute alternative strategies. We formulate three propositions for each strategic path. To avoid being stuck in the middle, TPLs are encouraged to either develop efficient services through servitized logistics chains and digital solutions or develop advanced solutions to integrate the consumer into the logistics network system through competencies to control increased levels of complexity.

Stellar Aberration from Earth and from a Satellite

In his endeavor to find a concrete evidence in favor of the Copernican picture of the solar system, the English astronomer James Bradley made a series of astronomical observations during the period (1725-1728) aiming to detect a stellar parallax. His findings, which manifested indeed an annual apparent cyclic motion of a star, were however at conflict with what is expected in a parallax. To his surprise, the result of every measurement obtained corresponded to what he expected to get in a measurement done three months earlier. Bradley realized that he was witnessing a new physical effect, and he presented an explanation that conceived light as a corpuscular stream travelling at finite velocity. Despite that Bradley’s explanation of the stellar aberration effect was inadequate, the equation which he derived to quantify the aberration angle, predicted a better estimation of light velocity, and the aberration phenomenon itself was a concrete support of heliocentrism. Stellar aberration as well as some other optical experiments, whose explanations posed challenges to the existing physical theories in the late nineteenth century paved the way for the emergence of the special theory of relativity. In the current work we employ the theory of universal space and time to show that a given direction in a frame of reference is tilted when observed in a moving frame by an angle that depends on the direction itself and the velocity of the moving frame. The latter fact is utilized to explain stellar aberration, determine the deviation of a star’s vision direction from its true one, and deduce its apparent position at any instant as a function of its latitude and time. The novel concept of aberration correction vector is employed to derive the apparent elliptic path of an observed celestial object at any time. The concept of graded inertial frames is introduced and utilized to deal with aberration when observed from a satellite in a similar way to its treatment when observed from Earth. The transformation matrix between a geocentric frame and a satellite’s non-rotating frame is derived and used to transform temporary Earthly vision directions to the satellite’s frame. Furthermore, the transformed vectors are adopted as transient fixed directions relative to which the vision directions of a star from the satellite are specified throughout one revolution. Satellites connective matrices are constructed to make geometric information regarding the celestial sphere in one frame immediately usable by observers on Earth and in all other satellites.

Magnetic field line random walk and solar energetic particle path lengths

Context. In 2020 May-June, six solar energetic ion events were observed by the Parker Solar Probe/IS⊙IS instrument suite at ≈0.35 AU from the Sun. From standard velocity-dispersion analysis, the apparent ion path length is ≈0.625 AU at the onset of each event. Aims. We develop a formalism for estimating the path length of random-walking magnetic field lines to explain why the apparent ion path length at an event onset greatly exceeds the radial distance from the Sun for these events. Methods. We developed analytical estimates of the average increase in path length of random-walking magnetic field lines, relative to the unperturbed mean field. Monte Carlo simulations of field line and particle trajectories in a model of solar wind turbulence were used to validate the formalism and study the path lengths of particle guiding-center and full-orbital trajectories. The formalism was implemented in a global solar wind model, and the results are compared with ion path lengths inferred from IS⊙IS observations. Results. Both a simple estimate and a rigorous theoretical formulation are obtained for field-lines’ path length increase as a function of path length along the large-scale field. From simulated field line and particle trajectories, we find that particle guiding centers can have path lengths somewhat shorter than the average field line path length, while particle orbits can have substantially longer path lengths due to their gyromotion with a nonzero effective pitch angle. Conclusions. The long apparent path length during these solar energetic ion events can be explained by (1) a magnetic field line path length increase due to the field line random walk and (2) particle transport about the guiding center with a nonzero effective pitch angle due to pitch angle scattering. Our formalism for computing the magnetic field line path length, accounting for turbulent fluctuations, may be useful for application to solar particle transport in general.

Ni/CeO2 promoted Ru and Pt supported on FeCrAl gauze for cycling methane catalytic partial oxidation—CPOX

Stranded natural gas is economically unattractive due to high operating and investment costs of conventional technologies necessary to bring it to market. However, milli-second reactors operating at a GHSV up to 200 000 h−1 reduce investment. The first step of a gas-to-liquids process produces syngas—a mixture of CO and H2. Here, we propose promoted Ni-based catalysts supported on FeCrAl knitted gauze to partially oxidize CH4 in air to syngas. High syngas selectivities at 1 bar, 700 °C and CH4/O2 ratios of 2.5 to 5 suggests an apparent direct reaction path to CO and H2. Ru promoted catalysts had higher turnover rates in CH4 activation compared to Ni, Ni-Pt and Ni-Pt-Ru. All catalysts containing Pt formed carbon species refractory to air regeneration at 700 °C. 2.25% Ni with 0.1% Ru had the highest CH4 turnover rate (155 mol s−1 mol−1) and CO selectivity (80%) at a CH4/O2 ratio 2.5. CH4 conversion and CO production were constant after 50 reaction-regeneration cycles that dosed the catalyst for 25 min with methane/air followed by an equal time in air at the same reaction temperature.

Paleomagnetism of the Sette-Daban Meso-Neoproterozoic magmatic complex of the southeastern margin of the Siberian platform

The interval of ~ 1000 - ~ 900 Ma is one of the key ones in the history of the evolution of the Siberian Platform. At this time, the formation of the neoproterozoic supercontinent Rodinia took place, which undoubtedly found its reflection in the geological annals of Siberia. A reflection of the kinematics of the Siberian platform is its apparent pole wander path (APWP), the development of which will help to clarify the geodynamic in which the platform was at the beginning of the Neoproterozoic. However, not many objects of this age are known within the Siberian Platform, suitable for performing paleomagnetic determinations. The consequence of this is a very limited number of existing reliable poles, obtained either from sedimentary rocks with very imprecise age limits, or from rocks of the Yenisei Ridge and Taimyr with an ambiguous structural position. This paper presents the results of paleomagnetic studies of the Proterozoic igneous rocks of the Sette-Daban complex of the southern Verkhoyansk region, the formation of which took place ~ 1000-970 Ma ago. Detailed thermal magnetic cleaning made it possible to reveal the high-temperature (HT) characteristic component in a significant part of the samples. It has maximum unblocking temperatures of about 580 ° C, lying in the region of the Curie point of magnetite. The average direction of the characteristic component for the sills sampled in the valley of the Yudoma, coincides with the direction obtained earlier on the same bodies. The calculated paleomagnetic pole for the intrusive bodies of the Sette-Daban magmatic complex (Plat = 5.8 °, Plong = 182.9 °, dp / dm = 9.0 ° / 14.4 °) confirms and refines the previously obtained pole for the rocks of this complex, and also indicates that Siberia in the range of ~ 970-1000 Ma was located in the northern hemisphere in tropical latitudes (~ 26 ° N). The analysis of the available geochronological and geochemical data, coupled with new paleomagnetic data, made it possible to clarify the age of the Sette-Daban magmatic event and limit it within ~ 970-1000 Ma.

Demonstrating the Sagnac Effect Using Tabletop Optics on a Rotary Platform

A Sagnac interferometer splits an incident beam of light into two components which travel in opposite directions of the same path. Consequently, each beam travels an equivalent distance. However, by rotating the entire apparatus at a sufficient speed, a noticeable change in the beams’ interference pattern is observed. This pattern results from one beam travelling against rotation and the other travelling with rotation, resulting in an increase or decrease in apparent path length, respectively. This is known as the Sagnac Effect. By using a traditional mirror-and-laser interferometer setup and a large turntable, we demonstrate the Sagnac Effect by showing that a given angular velocity results in a phase shift which matches what is predicted.

Construction and Automation of a Microcontrolled Solar Tracker

A solar tracker can be defined as an electromechanical system capable of following the apparent path of the Sun, in order to orient an array of solar panels and/or collectors directly to the solar rays, maximizing the collected energy. Accordingly, the present work describes the process of building and automating a micro-controlled solar tracker. Two mobile structures were built, one equipped with high-precision step motors and four luminosity sensors separated in quadrants by a cross structure, and the other equipped with DC motors and the 275 Wp solar panel, allowing the design and evaluation of the behavior of each structure separately. The control and automation system is centralized in an Arduino MEGA2560 microcontroller, which runs the tracking and positioning algorithms. The built prototype allows us to carry out studies of solar tracking strategies based on sensor and control systems applied to DC motors.

Vertically Transported Graphene Oxide for High-Performance Osmotic Energy Conversion.

Reverse electrodialysis is a promising method to harvest the osmotic energy stored between seawater and freshwater, but it has been a long‐standing challenge to fabricate permselective membranes with the power density surpassing the industry benchmark of 5.0 W m−2 for half a century. Herein, a vertically transported graphene oxide (V‐GO) with the combination of high ion selectivity and ultrafast ion permeation is reported, whose permeation is three orders of magnitude higher than the extensively studied horizontally transported GO (H‐GO). By mixing artificial seawater and river water, an unprecedented high output power density of 10.6 W m−2 is obtained, outperforming all existing materials. Molecular dynamics (MD) simulations reveal the mechanism of the ultrafast transport in V‐GO results from the quick entering of ions and the large accessible area as well as the apparent short diffusion paths in V‐GO. These results will facilitate the practical application of osmotic energy and bring an innovative design strategy for various systems involving ultrafast transport, such as filtration and catalysis.

Can Moderately Rarefied Gas Transport Through Round and Flat Tight Channels of Fractured Porous Media be Described Accurately?

This paper provides critical insights into the rigorous formulation of moderately rarefied gas transport through narrow channels in naturally and induced fractured porous media, such as gas shale rocks, approximated as round (cylindrical) and flat (slit) types. This formulation considers critical improvements over the previous attempts by proper implementation of the effective equivalent mean hydraulic radius of tight flow channels, the wall-slip effect accommodation of Maxwell (Philos Trans R Soc Lond A 170:231–256, 1879), the variable cross-section hard sphere model of gas molecules and the modified bulk mean free-path of Bird (Phys Fluids 26(11):3222–3223, 1983. https://doi.org/10.1063/1.864095), the apparent viscosity and mean free path for the confined-state gas behavior modification, the flow through narrow capillary tubes represented by a Hagen–Poiseuille-type equation, the Knudsen diffusivity, and an improved relationship between the apparent permeability and the intrinsic permeability. The description of gas transport through extremely tight channels is accomplished by superposition of the Poiseuille bulk flow (convection) and the Knudsen transport (diffusion) mechanisms. This approach is applied to investigate the accuracy of several previous studies on the modeling of gas transport through extremely tight narrow channels of round and flat types under moderately rarefied conditions. Although the simulation results reported by the previous studies of Roy et al. (J Appl Phys 93(8):4870–4879, 2003), Javadpour (J Can Pet Technol 48(8):16–21, 2009), and Veltzke and Thoming (J Gas Mech 698:406–422, 2012) appear to follow the trends observed in the experimental studies of Roy et al. (2003) flowing argon gas through a round channel (tube) and Ewart et al. (J Gas Mech 584:337–356, 2007. https://doi.org/10.1017/S0022112007006374) flowing helium gas through a single straight flat narrow channel, it is concluded that these results are not actually accurate for several reasons. The accuracy of the basic model presented by Javadpour (2009) suffers from some formulation issues and the low-order accuracy of the numerical approximations. The complicated model presented by Veltzke and Thoming (2012) is impractical and difficult because of the two-dimensional solutions of the Navier–Stokes equations with no-slip boundary condition and produces inaccurate solutions because of the improper definition of the effective radius of the straight flat narrow channel. The improved pressure equation of the compressible rarefied gas flow in tight channels developed in the present paper is highly nonlinear. The possibility of numerical calculation errors associated with the solution of the differential pressure equation was eliminated completely by an application of an integral transformation by facilitating a pseudo-transfer or flow potential function, and the solution of this equation was obtained accurately and fully analytically. It is shown that the proper formulation and accurate analytical solution developed in this paper can indeed lead to significantly accurate matches of the same experimental data than those reported by the previous studies. Thus, the deviation of the previous simulation results from the experimental data cannot be attributed simply to possible experimental errors associated with the laboratory tests but also to the limitations in formulation and inaccuracies in numerical solution. The exercises presented in this paper reveal that the previous modeling efforts certainly involve various types of errors and the experimental data cannot be matched by the gas transport models simply by adjusting the values of the unknown model parameters unless the models and their parameters are theoretically meaningful.

Kantian Ethics and Utopian Thinking

Is Kantian Ethics guilty of utopian thinking? First, potentially good and bad uses of utopian ideals are distinguished, then an apparent path is traced from Rousseau’s unworkable political ideal to Kant’s ethical ideal. Three versions of Kant’s Categorical Imperative (and their counter–parts in common moral discourse) are examined briefly for the ways that they may raise the suspicion that they manifest or encourage bad utopian thinking. In each case Kantians have available responses to counter the suspicion, but special attention is directed to the version that says “Act on the maxims of a universally law–giving member of a kingdom of ends.” Interpretations vary, but here primary focus is on one contemporary reconstruction and development of this central idea. Several objections suggest that this idea encourages bad utopian thinking are briefly addressed: that we cannot count on everyone to follow ideal rules, that even conscientious people disagree in their moral judgments, and that theories that allow exceptions to familiar moral rules create a “slippery slope” to moral chaos.

New paleomagnetic results from the ca. 1.68–1.63 Ga mafic dyke swarms in Western Shandong Province, Eastern China: Implications for the reconstruction of the Columbia supercontinent

The existence of Paleo-Mesoproterozoic supercontinent Columbia (aka Nuna) was established decades ago, but the position of North China Craton within Columbia is still highly debated due to the paucity of available high-quality paleomagnetic and reliable geological constraints. Precise geochronological dating of extensive Mesoproterozoic mafic dyke swarms in Western Shandong Province (also named the Luxi area), China reveals two phases of dyke emplacement at ~1.68 Ga and ~1.63 Ga. In this paper, we report new paleomagnetic and rock magnetic results obtained from approximate 160 samples (16 sites) collected from these two phases of mafic dyke swarms in the Luxi area with the aim of pinpointing the location of North China Craton within Columbia supercontinent in this time interval. Rock magnetic experiments confirm that either magnetite or titanomagnetite is the main magnetic carrier in these dykes. Stepwise thermal demagnetization revealed two paleomagnetic poles. For the ~1.63 Ga dykes, normal and reversed high-temperature remanent magnetization directions yield a mean direction (D/I) of 86.1°/53.5° (κ = 43.3, α95 = 7.9°, N = 9). These directions pass a reversal test and are interpreted as primary remanences. The corresponding paleomagnetic pole is calculated at 20.8°N, 182.5°E (κ = 28.3, A95 = 8.3°, N = 9). This pole passes the examination of secular variation of geomagnetic field (Deenen et al., 2011, 2014). It fulfills a Van der Voo (1990) value Q = 6 and is therefore suggested to be a ‘key’ pole demarcating the Precambrian North China Craton. For the ~1.68 Ga dykes, only the normal directions are isolated with a mean direction (D/I) of 89.1°/47.1° (κ = 35.0, α95 = 13.1°, N = 5) with a corresponding paleomagnetic pole of 17.8°N, 184.9°E (κ = 29.6, A95 = 14.3°, N = 5). This pole passes the examination of secular variation of geomagnetic field. Finally we select the ~1.63 Ga high-quantity paleomagnetic pole in order to depict a more detailed apparent pole wander path (APWP) to compare with the other major Precambrian cratons. Combined with other geological evidence, our reconstruction scenario supports the spatio-temporal connection between the Baltica, North Australian Craton and North China Craton.

Properties of High-Energy Solar Particle Events Associated with Solar Radio Emissions

We have analysed 58 high-energy proton events and 36 temporally related near-relativistic electron events from the years 1997 – 2015 for which the velocity dispersion analysis of the first-arriving particles gave the apparent path lengths between 1 and 3 AU. We investigated the dependence of the characteristics of the proton events on the associations of type II, III, and IV radio bursts. We also examined the properties of the soft X-ray flares and coronal mass ejections associated with these events. All proton events were associated with decametric type III radio bursts, while type IV emission was observed only in the meter wavelengths in some of the events (32/58). Almost all proton events (56/58) were associated with radio type II bursts: 11 with metric (m) type II only, 11 with decametric–hectometric (DH) only, and 34 with type II radio bursts at both wavelength ranges. By examining several characteristics of the proton events, we discovered that the proton events can be divided into two categories. The characteristics of events belonging to the same category were similar, while they significantly differed between events in different categories. The distinctive factors between the categories were the wavelength range of the associated type II radio emission and the temporal relation of the proton release with respect to the type II onset. In Category 1 are the events which were associated with only metric type II emission or both m and DH type II and the release time of protons was before the DH type II onset (18/56 events). Category 2 consists of the events which were associated with only DH type II emission or both m and DH type II and the protons were released at or after the DH type II onset (31/56 events). For seven of the 56 events we were not able to determine a definite category due to timing uncertainties. The events in Category 1 had significantly higher intensity rise rates, shorter rise times, lower release heights, and harder energy spectra than Category 2 events. Category 1 events also originated from magnetically well-connected regions and had only small time differences between the proton release times and the type III onsets. The soft X-ray flares for these events had significantly shorter rise times and durations than for Category 2 events. We found 36 electron events temporally related to the proton events, which fulfilled the same path length criterion as the proton events. We compared the release times of protons and electrons at the Sun, and discovered that in 19 of the 36 events protons were released almost simultaneously (within {pm},7 minutes) with the electrons, in 16 events protons were released later than the electrons, and in one event electrons were released after the protons. The simultaneous proton and electron events and the delayed proton events did not unambiguously fall in the two categories of proton events, although most of the events in which the protons were released after the electrons belonged to Category 2. We conclude that acceleration of protons in Category 1 events occurred low in the corona, either by CME-driven shocks or below the CMEs in solar flares or in CME initiation related processes. It seems plausible that protons in Category 2 events were accelerated by CME-driven shocks high in the solar corona. Large delays of protons with respect to type III onsets in the events where protons were released after the electrons suggest late acceleration or release of protons close to the Sun, but the exact mechanism causing the delay remained unclear.