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Magnetic targeting of drug carriers is commonly studied at macroscopic scales, while its impact on drug transport across individual cell membranes remains poorly quantified. Here, we present a theoretical and numerical model of magnetically assisted drug transport across the membrane of a single tumor cell exposed to magnetic field gradients. Extracellular transport is described by an advection-diffusion equation that couples passive diffusion with magnetophoretic drift, whereas intracellular transport is governed by diffusion and first-order uptake kinetics. The cell membrane is modeled as a semi-permeable interface with finite permeability, providing explicit coupling between extracellular and intracellular domains. Assuming spherical symmetry, the coupled transport equations are solved using finite-difference schemes, with magnetic forcing represented through an effective drift velocity vmag and interpreted using the magnetic Peclet number. To enable a controlled comparison between healthy and tumor cells, identical geometric, diffusive, and magnetic parameters are used, while biological differences are introduced solely through membrane permeability and intracellular uptake rates. By separating cumulative membrane delivery from cumulative intracellular uptake, the model resolves ambiguities arising from heterogeneous uptake kinetics. The results show that magnetophoretic drift enhances near-membrane drug accumulation and effective transmembrane flux without modifying intrinsic membrane properties. Magnetic targeting therefore acts as a transport amplifier, magnifying pre-existing biological differences and producing a larger model-predicted delivery advantage in tumor cells. Overall, the framework identifies the magnetic Peclet number as the key parameter governing the transition from diffusion-dominated to drift-enhanced cellular drug transport.

In this study, we use an approach based on the power flow equation (PFE) to investigate how the bandwidth, equilibrium mode distribution (EMD) and steady-state distribution (SSD) of a designed doubly clad W-type microstructured plastic optical fiber (mPOF) with a graded-index (GI) core distribution evolves with wavelength. Our analysis shows that the bandwidth decreases as fiber length increases at all wavelengths studied, while it increases with the wavelength. This behavior is linked to a reduction in mode delay time per unit length, leading to decreased modal dispersion. On the other hand, widening the inner cladding of the W-type GI mPOF causes a decrease in bandwidth due to the rise in the number of guided modes, which increases modal dispersion. When comparing the bandwidth of the W-type GI mPOF, which is 2.7 GHz km at λ = 645 nm, to the measured bandwidth of the conventional GI POF, which is 460 MHz m at λ = 633 nm, the W-type GI mPOF clearly exhibits a substantially higher bandwidth. Another important benefit of mPOFs over traditional POFs lies in their ability to precisely adjust air-hole diameters and pitches with greater flexibility, without the need for complex doping processes as required for standard POFs. These results offer insights for communication and sensory systems that use multimode GI mPOFs across varying wavelengths.

A new design of multimode W-type (doubly clad) microstructured plastic optical fiber (mPOF) with graded-index (GI) distribution of the core is proposed, along with a methodology for examining transmission along it. The power flow equation’s (PFE) numerical solution yields the transmission properties of the W-type GI mPOF. We have demonstrated that the coupling length L c at which an equilibrium mode distribution (EMD) is reached in W-type GI mPOF is shorter than the length experimentally found for the conventional singly- clad (SC) GI POF. This results from leaky mode losses, which lower the length L c in W-type GI mPOF by lowering the amount of higher guided modes engaged in the coupling process. As a result, the bandwidth of W-type GI mPOF significantly increases. It is noteworthy that, when compared to the experimental bandwidth of commercially available conventional POFs, the bandwidth of the W-type GI mPOF proposed in this work is noticeably higher. Consequently, the bandwidth performance of short-haul communication lines may be significantly improved by using such a designed W-type GI mPOF.

We investigate mode coupling in a multimode graded-index microstructured polymer optical fiber (GI mPOF) with a solid core by solving the time-independent power flow equation (TI PFE). Using launch beams with various radial offsets, it is possible to calculate for such an optical fiber the transients of the modal power distribution, the length Lc at which an equilibrium mode distribution (EMD) is reached, and the length zs for establishing a steady-state distribution (SSD). In contrast to the conventional GI POF, the GI mPOF explored in this study achieves the EMD at a shorter length Lc. The earlier shift to the phase of slower bandwidth decrease would result from the shorter Lc. These results are helpful for the implementation of multimode GI mPOFs as a part of communications and optical fiber sensory systems.

This paper compares the employment outcomes of liberal arts graduates from Dutch university colleges with those of their peers who pursued conventional, subject-specific bachelor’s degrees. Using data from the Dutch National Alumni Survey, the analysis includes 14,933 respondents who completed a master’s programme at a research university, with 210 of them holding a university college degree. Logistic, multinomial, and OLS regression analyses were performed on six labour market outcomes: employment status, time to first paid job, vertical match, horizontal match, vertical and horizontal match combination, and hourly wage from regular work. Propensity score matching was used as a robustness check. The results show that holding a university college degree is not associated with any distinct advantages or disadvantages in the job market. While a liberal arts bachelor’s degree has a negative effect on obtaining employment in STEM professions, no statistically significant differences, neither negative nor positive, were found in other outcomes. This suggests that university colleges do not lack the capacity to prepare students for the labour market.

An important condition for the performance sustainability of organizations, in the public and state sector, is the maintenance and improvement of the employee motivation policy model. Motivation for work has a significant impact on the success of modern organizations; the impact is multidimensional and complex, and it has been confirmed empirically. Motivation is influenced by numerous factors, of different influence and hierarchy, which depend on socio-economic conditions and cultural determinants, but also on the characteristics of employees, and it is necessary to constantly monitor them. The paper presents a sustainable model of employee motivation in public administration and the results of research on the hierarchy and the impact of motivation factors on employees of different demographic characteristics. The research was conducted by an anonymous survey of 2128 respondents (1576 employees in the state administration and 552 persons employed in the Republic of Serbia outside the state administration), in the period March–June 2020. The questionnaire developed for this research has 16 questions on motivating factors with a scale with a high level of internal consistency. Using one-factor analysis of variance (ANOVA), tests of subsequent comparisons, and t-test, statistically significant differences are determined for the influence of motivational factors on respondents of different levels of education, age, role in organization, gender, and family status—also, the magnitude of influence ranges from small to large. The influence of motivational factors is greater for older people, for people with a higher level of education, for managers in relation to workers, for women in relation to men, as well as for persons in marriage in relation to persons out of wedlock. By applying multi-criteria analysis, the factors are ranked: the amount of salary and good interpersonal relations are at the top, while criticism and information about work are in the last positions. As a factor that negatively affects motivation, low wages stands out. The difference in the motivation of state administration members was determined by comparing the results of motivational factors’ influence with the appropriate sample of employees outside the state administration. Differences were registered for 15 out of 16 factors (only for the factor high wages, there is no difference), and the magnitude of the impact is medium and small.

Solving the time-dependent power flow equation (PFE) provides a useful method to study the transmission bandwidth of step-index silica photonic crystal fibers (SI SPCFs). The transmission bandwidth of these kinds of fibers is determined for different air-hole structures (different numerical apertures (NAs)) and different distribution widths of the Gaussian launch beam. The results indicate that the lower the NA of SI SPCFs, the higher the bandwidth (for example, for a lower NA of SI SPCFs, a bandwidth that is eight times larger is obtained at a fiber length of 3500 m). The narrower launch beam at short fiber lengths results in a wider bandwidth. The longer the fiber (>300 m), the much less the effect of the launch beam width on the bandwidth. The bandwidth becomes independent of the width of the launch beam distribution at the fiber length at which a steady-state distribution (SSD) is reached. These results are useful for some potential applications, such as high capacity transmission optical fiber systems.

By solving the time-dependent power flow equation, we present a novel approach for evaluating the bandwidth in a multimode step-index polymer photonic crystal fiber (SI PPCF) with a solid core. The bandwidth of such fiber is determined for various layouts of air holes and widths of Gaussian launch beam distribution. We found that the lower the NA of SI PPCF, the larger the bandwidth. The smaller launch beam leads to a higher bandwidth for short fibers. The influence of the width of the launch beam distribution on bandwidth lessens as the fiber length increases. The bandwidth tends to its launch independent value at a particular fiber length. This length denotes the onset of the steady state distribution (SSD). This information is useful for multimode SI PPCF applications in telecommunications and optical fiber sensing applications.

Multimode polymer optical fibers (POFs) are considered to be the best choice for short-distance communication lines due to their advantageous properties. One must pay close attention to POFs’ most crucial transmission property, bandwidth (BW), which affects the fibers’ transmission capacity. The improvement of POF transmission qualities, particularly BW, which is its most crucial property, has been the subject of many researches during the past few decades. Both experimental and theoretical approaches have been used to address this issue. Up to now, there were no commercial simulation tools available for studying the transmission characteristics of multimode optical fibers. To overcome this problem, the modal continuum approach is employed to characterize light transmission in various kinds of multimode optical fibers. This modal continuum approach, which uses the time-dependent power flow equation (TD PFE), plays the most important role in the theoretical approaches. The PFE is the most comprehensive because it takes into account attenuation, mode coupling and modal dispersion, which significantly affects the BW. It can also be modified to accommodate various refractive index profiles, including step-index (SI), W-type index and graded index (GI) profiles. This review analyzes the pertinent literature related to the use of modal continuum-based models for BW modeling in conventional and microstructured multimode POFs. An overview of methodologies for optical fiber analysis with a focus on modal continuum approximation, and solutions to the TD PFE for various multimode fiber types, is provided.