Emergence Of Wave Research Articles

Stratified inclined duct: two-layer hydraulics and instabilities

The stratified inclined duct (SID) sustains an exchange flow in a long, gently sloping duct as a model for continuously forced density-stratified flows such as those found in estuaries. Experiments have shown that the emergence of interfacial waves and their transition to turbulence as the tilt angle is increased appears to be linked to a threshold in the exchange flow rate given by inviscid two-layer hydraulics. We uncover these hydraulic mechanisms by (i) using recent direct numerical simulations (DNS) providing full flow data in the key flow regimes (Zhu et al., J. Fluid Mech., vol. 969, 2023, A20), (ii) averaging these DNS into two layers, and (iii) using an inviscid two-layer shallow-water and instability theory to diagnose interfacial wave behaviour and provide physical insight. The laminar flow is subcritical and stable throughout the duct and hydraulically controlled at the ends of the duct. As the tilt is increased, the flow becomes supercritical everywhere and unstable to long waves. An internal jump featuring stationary waves first appears near the centre of the duct, then leads to larger-amplitude travelling waves, and to stronger jumps, wave breaking and intermittent turbulence at the largest tilt angle. Long waves described by the (nonlinear) shallow-water equation are interpreted locally as linear waves on a two-layer parallel base flow described by the Taylor–Goldstein equation. This link helps us to interpret long-wave instability and contrast it with short-wave (e.g. Kelvin–Helmholtz) instability. Our results suggest a transition to turbulence in SID through long-wave instability relying on vertical confinement by the top and bottom walls.

Turbulent stress within dead zones and magnetic field dragging induced by Rossby vortices

ABSTRACT By means of three-dimensional resistive-magnetohydrodynamical models, we study the evolution of the so-called dead zones focused on the magnitude of the Reynolds and Maxwell stresses. We consider two different types of static resistivity radial profiles that give rise to an intermediate dead zone or an intermediate active zone. As we are interested in analysing the strength of angular momentum transport in these intermediate regions of the disc, we use as free parameters the radial extent of the intermediate dead (Δridz) or active (Δriact) zones, and the widths of the inner ($H_{b_1}$) and outer ($H_{b_2}$) transitions. We find that regardless of the width or radial extent of the intermediate zones, Rossby wave instability (RWI) develops at these transition boundaries, leading to the emergence of vortices and spiral waves. In the case of an intermediate dead zone when $H_{b_1}\, ,H_{b_2}\le 0.8$, the vortices are almost completely confined to the dead zone. Remarkably, we find that the formation of vortices at the inner transition can drag magnetic field lines into the dead zone stirring up the region that the vortex covers (reaching an α ≈ 10−2 value similar to that of an active zone). Vortices formed in the outer transition only modify the Reynolds stress tensor. Our results can be important to understanding angular momentum transport in poorly ionized regions within the disc due to magnetized vortices within dead zones.

Simulation of spatial rogue waves in actively Q-switched solid-state laser with transverse mode locking

We report the generation of spatial rogue waves in the actively Q-switched Nd:YAG laser with several transverse modes and negligible nonlinear effects in the cavity. We discuss a basic theoretical model that is able to reproduce the experimental observations of spatial rogue waves in the output Q-switched pulses as a result of the coherent superposition of transverse modes. The simulated rogue wave statistics depends on the configuration of the lasing modes and take a more pronounced L-shaped form in the case of highly anisotropic mode distribution and reduced frequency spacing between the modes. For larger frequency spacing between the modes, the mode-locking effects result in the periodic dynamics of the transverse beam profile and formation of spatio-temporal rogue waves. These results indicate that transverse mode-locking and spatial symmetry breaking through anisotropy in the mode configuration represent factors responsible for spatial rogue wave emergence in multimode lasers with low nonlinearity.

Multisoliton interactions approximating the dynamics of breather solutions

AbstractNowadays, breather solutions are generally accepted models of rogue waves. However, breathers exist on a finite background and therefore are not localized, while wavefields in nature can generally be considered as localized due to the limited sizes of physical domain. Hence, the theory of rogue waves needs to be supplemented with localized solutions, which evolve locally as breathers. In this paper, we present a universal method for constructing such solutions from exact multisoliton solutions, which consists in replacing the plane wave in the dressing construction of the breathers with a specific exact N‐soliton solution converging asymptotically to the plane wave at large number of solitons N. On the example of the Peregrine, Akhmediev, Kuznetsov–Ma, and Tajiri–Watanabe breathers, we show that constructed with our method multisoliton solutions, being localized in space with characteristic width proportional to N, are practically indistinguishable from the breathers in a wide region of space and time at large N. Our method makes it possible to build solitonic models with the same dynamical properties for the higher order rational and super‐regular breathers, and can be applied to general multibreather solutions, breathers on a nontrivial background (e.g., cnoidal waves), and other integrable systems. The constructed multisoliton solutions can also be generalized to capture the spontaneous emergence of rogue waves through the spontaneous synchronization of soliton norming constants, though finding these synchronization conditions represents a challenging problem for future studies.

184 Effects of cetrorelix on the growth pattern of the dominant follicle and follicular wave emergence in cattle

184 Effects of cetrorelix on the growth pattern of the dominant follicle and follicular wave emergence in cattle

A serious game about Covid-19: design and evaluation study

<span lang="EN-US">As many countries experience the emergence of new waves of Covid-19, many governments around the world have reminded their citizens of the need for an engaging intervention that could improve compliance with Covid-19 safe behaviors using the media general public or social media. In the face of the serious threat of Covid-19, immunity issues are currently the subject of various research and studies. A promising approach is to use video game culture to educate and train citizens to healthily adopt eating habits to strengthen the immune system. The objective of this study is to develop a prototype of a serious game (SG) on how to strengthen the immune defenses in order to be able to fight a coronavirus infection and to constitute an anti-virus barrier. After defining the learning objectives by interviewing the stakeholders, we searched the scientific literature to establish the relevant theoretical bases. The learning contents have been validated by biology teachers. The learning mechanisms were then determined based on the learning objectives. The obtained experimental results show that 92% of the participants in the study have appreciated the quality of the scenario and the way in which the concept of interaction between the different game elements was presented.</span>

Turbulence Transitions in Kelvin–Helmholtz Instability “Tube” and “Knot” Dynamics: Vorticity, Helicity, and Twist Waves

We address the sources and dynamics of vorticity and helicity and their relations in transitions to turbulence arising due to Kelvin–Helmholtz instability (KHI) “Tube” and “Knot” (T&K) events. Such events are common in the atmosphere and oceans, and initial numerical simulations reveal that T&K dynamics significantly accelerate turbulence transitions and enhance KHI peak and mean energy dissipation rates. KHI T&K events arise where emerging KH billows exhibit varying wavelengths, phases, amplitudes, and/or discontinuities along their axes. As the KH billows intensify, these regions evolve roughly orthogonal billow cores and induced vortex tubes in close proximity. Their mutual advection as they intensify induces large-amplitude Kelvin vortex waves, or “twist waves”, that arise where locally uniform vortices are distorted by axial or radial advection. The twist waves propagate along, and fragment, the vortex tubes and billow cores, thus accounting for the emergence of helicity and the down-scale energy, enstrophy, and helicity fluxes within the turbulence inertial range. We describe the results of four direct numerical simulations (DNS) addressing KHI T&K dynamics in large and idealized small domains. The large-domain vorticity fields reveal the character and diversity of KHI T&K dynamics, the emergence of twist waves at larger and smaller scales, and their driving of turbulence transitions. Two small-domain DNS exhibit idealized KHI T&K events arising from KH billows that are mis-aligned and that exhibit phase variability along their axes. A third examines the interactions of two vortex tubes in close proximity. These reveal that twist waves drive the character and evolutions of the vorticity and helicity fields.

Characterization of Postpartum Ovarian Follicular Development Pattern in Crossbred Cows

Background: The postpartum period is crucial for cattle reproduction. The length of postpartum anestrus significantly impacts reproductive efficiency. Apparently enhanced energy attribution to milk production may lead to anestrus by delaying the onset of follicular activity. The absence of an ovulation stimulus, rather than insufficient follicle growth, determines the limited duration until ovulation. The current study was aimed to document the postpartum ovarian dynamics in crossbred Jersey cows. Methods: The study was conducted in ten postpartum crossbred Jersey cows. Transrectal ultrasonography was performed to record the follicular development pattern from parturition till two ovulation or 90 days postpartum on alternate days. The data was analyzed for follicular wave emergence, no of follicular waves, size of the dominant follicle and ovulatory status. Result: Fourty per cent of crossbred Jersey cows showed cyclicity and rest 60 per cent of cows are in anestrum. The mean diameter size of the dominant follicle in ovulated cows is 12.2±1.2 mm and in anestrum cows is 10.6±0.4 mm. The first wave emergence is 5.7±0.3 and 10.8±5.9 day in OV and NOV group respectively. In conclusion significant difference could be observed in emergence of first, second, third, fourth and fifth follicular wave emergence, growth phase duration, rate, size of the dominant follicle and duration of wave between postpartum ovulated and anestrum cows.

The Impact and Development of Modern Internet Financial Technology on the Traditional Financial Industry

The financial technology industry has experienced significant growth due to the rapid integration of artificial intelligence, big data, cloud computing, Internet of Things, blockchain, and other information technologies into financial businesses. This growth can be attributed to the emergence of a new wave of scientific and technological revolution and industrial transformation. The integration has facilitated the progress of the financial technology industry. This study employs the Logistic regression model to examine the effects on the conventional financial sector. The author's research provides a detailed examination of the developmental trajectory of Internet finance and financial technology, while also assessing the present challenges faced by Internet finance and its repercussions on the conventional financial sector. Through a comprehensive examination of the text in its entirety, a concise overview of the historical and prospective financial environment might yield a more perceptive comprehension of the ramifications of emerging technologies on the conventional financial sector. The present study aims to provide a thorough examination of the paper, with the expectation that it will enable individuals to get a more lucid understanding of the overarching circumstances.

Investigating the Impact of Technostress on Perceived Hybrid Learning Environment and Academic Performance

For the betterment of society, education plays a significant role in helping human beings in both tangible and intangible manner. From time to time, various transformations came to the teaching and learning pedagogy. Moreover, it has been evaluated by respective available resources. During and post-COVID-19, we have seen a considerable inclination towards hybrid learning. So, as a researcher, we also need to evaluate whether it has been progressing well. The emergence of different waves of pandemics across the globe has forced higher education institutes to develop and implement new educational models and policies that help to improve the quality of education and learning. However, we also need to examine the impact of these new modalities. For this, Tecnologico de Monterrey, Mexico, has also implemented its novel hybrid educational model, ' HyFlex+Tec,' to continue and uplift academic activities. This model has proposed access to quality education during and post-pandemic crisis and offers the possibility of providing a more environmentally friendly educational model. This study aims to explore the role of technostress in the association between a hybrid learning environment and students' academic performance and to reflect on how this new mode of blended learning could promote 'green-based' learning in an era of climate emergency. For this, we deployed a Form-based online survey among students through the convenient sampling technique. In total, we received 94 registered responses. For statistical analysis of quantitative datasets, we used a free and open statistical application, i.e., Jamovi. After the regression-based examination, it has been noted that technostress fully mediates the relationship between the perceived hybrid learning environment and the academic performance of undergraduate students. The reason for the occurrence of technostress among students is the continuous change in modalities, where the adaptation of new digital tools (software and devices) in a short time affects academic performance, thereby causing a lack of participation in course activities. This research provides guidelines to the university and government policymakers to update or introduce new flexible degree programs (in-person and hybrid) to promote digital skills and the wellbeing of students.

Noise correlation analysis: the role of the inflection points in the formation of zero-time waves

SUMMARY The cross-correlation function (CCF) of seismic noise recorded at two stations often exhibits a prominent burst of energy near zero time. However, the excitation mechanism of such unexpected signals remains unclear. In this study, we demonstrate that this phenomenon arises from constructive interference of body waves radiating from sources near the mid-vertical plane between two receivers. This interference is driven by the occurrence of an inflection point effect in the traveltime difference between waves reaching the two receivers. When noise source distribution is asymmetric, the cumulative effect of such sources results in the generation of zero-time waves. It is noteworthy that a noise source distribution that is either uniform or follows a cosϕ pattern, with ϕ denoting the azimuth from the centre of the receiver pair, can counteract the formation of these waves. Additionally, our investigation reveals that this constructive interference does not occur in the correlation of 2-D surface waves. We used numerical simulation to support our findings. In conclusion, this study offers a theoretical explanation for the emergence of zero-time waves on the CCF and provides efficient means of investigating the extraction of inter-receiver waves with uneven noise source distribution.

Ruling out Efficacy of Hormonal Protocols alone or Fortified with Mineral and Bypass Fat for Treatment of Postpartum Anoestrus in Cattle

Background: High milk production and excellent fertility is a dream of livestock owners.The major reproductive disorders which lead to decrease the productivity and reproductive ability of farm animals is postpartum anestrous.Recently, kisspeptin was reported as game changer in the animal reproduction. Kisspeptin increases the number of follicles at wave emergence, oestrus response rate and duration of oestrus. Thus, indicating its potentiality for induction of oestrus in anestrous animals. Methods: The present study was conducted to compare the efficacy of Ovsynch and kisspeptin protocol and need of fortification for treatment of postpartum anestrous.Fifty postpartum anestrous cows were selected. The animals were divided into four treatment groups (10 cows in each) and treated with Ovsynch (Group I), Ovsynch fortified with mineral mixture (MM) and bypass fat (BPF) (Group II), kisspeptin (Group III) and kisspeptin fortified with MM +BPF (Group IV). The remaining 10 cows served as control (Group V). The oestrus response was recorded on the basis of behavioral signs, physical signs and clinico-gynaecological changes. The blood was collected following treatment for hormonal estimation. The pregnancy was confirmed on day 45 post AI using ultrasound. Result: The oestrusresponse was pronounced in Ovsynch as compared to kisspeptin groups. Further, fortification has enhanced the response. The serum oestrogen concentration increased following treatment and was significantly high on day of onset of oestruswith highest concentration in group II. The results indicate Ovsynchdistinguishly succeeded in addressing postpartum anestrus with fortification enhances fertility response.However, kisspeptin also emerged as a potent candidate for the resumption of cyclicity.

Ovarian activity and reproductive responses of lactating Angus cows due to a mineral supplementation throughout a timed AI protocol.

Two experiments were conducted to evaluate the effect of intramuscular administration of minerals during a TAI program on the reproductive responses of lactating Angus cows. All cows (n=353) were subjected to a 9-day TAI program based on CIDR insertion plus injections of estradiol, cloprostenol, and eCG, and then TAI 48 h later. In experiment 1, two groups were randomly created, one control with a placebo injection (CON, n=109), and the second received 10 mL of Fosfosan® (MIN, n=172) on day 0 of the synchronization. Conception rate (66.9 vs. 55%) and estrus percentage (55.8 vs. 44%) were higher (P≤0.05) in MIN than in CON cows. Given these results, a second experiment was conducted randomly assigning the cows to two treatments (n=36 each): a single injection of 10 mL of Fosfosan® (MIN-O) on day 0 or two injections of 10 mL of Fosfosan® (MIN-T) on synchronization days 0 and 7. Four cows of each treatment were randomly selected to be scanned with transrectal ultrasound before and during the synchronization protocol to assess ovarian structures and cyclicity, and at day 39 post-TAI for pregnancy diagnosis. Also, blood samples were obtained for the determination of serum minerals and progesterone (P4) concentrations. The number of mineral injections did not affect conception rate (P≥0.1229) conception rate, serum mineral and P4 concentrations, number, and size of emerging follicles, or follicle size according to 1 to 4 classifications. The MIN-T promoted (P<0.05) earlier follicular wave emergence than MIN-O. However, MIN-O cows had a dominant follicle of 15.12 mm, which is more significant (P<0.05) than that in MIN-T cows (13.5 mm). In conclusion, providing a single mineral injection of Fosfosan® at the start of a TAI program is an excellent reproductive strategy in lactating Angus cows to improve the dominant follicle growth, estrus response, and conception rate.

Effects of prostaglandin F2α treatment at follicular wave emergence on endometrial epidermal growth factor concentration on day 3 of the next estrous cycle and on fertility in dairy cows

Inadequate exposure to estradiol (E2) and progesterone (P4) may be the main causes of altered endometrial epidermal growth factor (EGF) profile, leading to reduced fertility in dairy cows. We hypothesized that PGF2α administration at different timings of the estrous cycle and stages of follicular development could change the profile of steroid hormones between luteolysis and estrus. This results in reduction in the peak concentration of endometrial EGF on day 3 (day 0 = estrus) in the next estrous cycle. In study 1, lactating Holstein cows were treated with PGF2α either on days 12–14 (selection phase group, n = 20) or on days 16–17 (control group, n = 24) of the estrous cycle. Blood samples were obtained before PGF2α treatment, 24 and 48 h after treatment, and on the day of estrus and ovulation for E2 and P4 assays. Endometrial tissues were collected by biopsy on day 3 for EGF assays. The duration from PGF2α treatment to both estrus and ovulation was longer in the selection phase group than in the control group (P < 0.05). The time between estrus and ovulation was longer in the selection phase group (P < 0.05). E2 concentrations were higher in the control group on the day of estrus (P < 0.05). P4 concentrations were not different between the groups. Endometrial EGF concentrations were lower in the selection phase group than in the control group (P < 0.05). In study 2, lactating Holstein cows were treated with PGF2α either on day 12 (selection phase group, n = 76) or day 16 (control group, n = 80). They were subjected to artificial insemination (AI) at estrus, and those that failed to ovulate by 24h after the first AI were subjected to second AI. On day 3, endometrial EGF concentration was determined. At estrus and on days 3 and 7, blood was collected for E2 and P4 assay from 20 randomly selected cows in each group before PGF2α treatment. The cows in the selection phase group exhibited lower EGF concentration, proportion of cows with normal EGF profile, and conception rate than cows in the control group (P < 0.05). On the day of estrus, E2 concentrations tended to be lower in the selection phase group than in the control group (P = 0.08). P4 concentrations were not different between the groups. These findings suggest that low E2 concentrations at estrus and low P4 concentrations for a prolonged period due to premature termination of CL in the absence of a dominant follicle are potential causes of altered endometrial EGF profile in dairy cows.

Digital entrepreneurship from cellular data: How omics afford the emergence of a new wave of digital ventures in health

Data has become an indispensable input, throughput, and output for the healthcare industry. In recent years, omics technologies such as genomics and proteomics have generated vast amounts of new data at the cellular level including molecular, structural, and functional levels. Cellular data holds the potential to innovate therapeutics, vaccines, diagnostics, consumer products, or even ancestry services. However, data at the cellular level is generated with rapidly evolving omics technologies. These technologies use scientific knowledge from resource-rich environments. This raises the question of how new ventures can use cellular-level data from omics technologies to create new products and scale their business. We report on a series of interviews and a focus group discussion with entrepreneurs, investors, and data providers. By conceptualizing omics technologies as external enablers, we show how characteristics of cellular-level data negatively affect the combination mechanisms that drive venture creation and growth. We illustrate how data characteristics set boundary conditions for innovation and entrepreneurship and highlight how ventures seek to mitigate their impact.

Unraveling the Dynamics of Omicron (BA.1, BA.2, and BA.5) Waves and Emergence of the Deltacton Variant: Genomic Epidemiology of the SARS-CoV-2 Epidemic in Cyprus (Oct 2021-Oct 2022).

Commencing in December 2019 with the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), three years of the coronavirus disease 2019 (COVID-19) pandemic have transpired. The virus has consistently demonstrated a tendency for evolutionary adaptation, resulting in mutations that impact both immune evasion and transmissibility. This ongoing process has led to successive waves of infections. This study offers a comprehensive assessment spanning genetic, phylogenetic, phylodynamic, and phylogeographic dimensions, focused on the trajectory of the SARS-CoV-2 epidemic in Cyprus. Based on a dataset comprising 4700 viral genomic sequences obtained from affected individuals between October 2021 and October 2022, our analysis is presented. Over this timeframe, a total of 167 distinct lineages and sublineages emerged, including variants such as Delta and Omicron (1, 2, and 5). Notably, during the fifth wave of infections, Omicron subvariants 1 and 2 gained prominence, followed by the ascendancy of Omicron 5 in the subsequent sixth wave. Additionally, during the fifth wave (December 2021-January 2022), a unique set of Delta sequences with genetic mutations associated with Omicron variant 1, dubbed "Deltacron", was identified. The emergence of this phenomenon initially evoked skepticism, characterized by concerns primarily centered around contamination or coinfection as plausible etiological contributors. These hypotheses were predominantly disseminated through unsubstantiated assertions within the realms of social and mass media, lacking concurrent scientific evidence to validate their claims. Nevertheless, the exhaustive molecular analyses presented in this study have demonstrated that such occurrences would likely lead to a frameshift mutation-a genetic aberration conspicuously absent in our provided sequences. This substantiates the accuracy of our initial assertion while refuting contamination or coinfection as potential etiologies. Comparable observations on a global scale dispelled doubt, eventually leading to the recognition of Delta-Omicron variants by the scientific community and their subsequent monitoring by the World Health Organization (WHO). As our investigation delved deeper into the intricate dynamics of the SARS-CoV-2 epidemic in Cyprus, a discernible pattern emerged, highlighting the major role of international connections in shaping the virus's local trajectory. Notably, the United States and the United Kingdom were the central conduits governing the entry and exit of the virus to and from Cyprus. Moreover, notable migratory routes included nations such as Greece, South Korea, France, Germany, Brazil, Spain, Australia, Denmark, Sweden, and Italy. These empirical findings underscore that the spread of SARS-CoV-2 within Cyprus was markedly influenced by the influx of new, highly transmissible variants, triggering successive waves of infection. This investigation elucidates the emergence of new waves of infection subsequent to the advent of highly contagious and transmissible viral variants, notably characterized by an abundance of mutations localized within the spike protein. Notably, this discovery decisively contradicts the hitherto hypothesis of seasonal fluctuations in the virus's epidemiological dynamics. This study emphasizes the importance of meticulously examining molecular genetics alongside virus migration patterns within a specific region. Past experiences also emphasize the substantial evolutionary potential of viruses such as SARS-CoV-2, underscoring the need for sustained vigilance. However, as the pandemic's dynamics continue to evolve, a balanced approach between caution and resilience becomes paramount. This ethos encourages an approach founded on informed prudence and self-preservation, guided by public health authorities, rather than enduring apprehension. Such an approach empowers societies to adapt and progress, fostering a poised confidence rooted in well-founded adaptation.

Trapped tidal currents generate freely propagating internal waves at the Arctic continental slope

Energetic tidal currents in the Arctic play an important role in local mixing processes, but they are primarily confined to the shelves and continental slopes due to topographic trapping north of their critical latitude. Recent studies employing idealized models have suggested that the emergence of higher harmonic tidal waves along these slopes could serve as a conduit for tidal energy transmission into the Arctic Basin. Here we provide observational support from an analysis of yearlong observations from three densely-instrumented oceanographic moorings spanning 30 km across the continental slope north of Svalbard (sim81.3^{circ }N). Full-depth current records show strong barotropic diurnal tidal currents, dominated by the K_1 constituent. These sub-inertial currents vary sub-seasonally and are strongest at the 700-m isobath due to the topographic trapping. Coinciding with the diurnal tide peak in summer 2019, we observe strong baroclinic semidiurnal currents exceeding 10 cm s^{-1} between 500 m and 1000 m depth about 10 km further offshore at the outer mooring. In this semidiurnal band, we identify super-inertial K_2 waves, and present evidence that their frequency, timing, polarization, propagation direction and depths are consistent with the generation as higher harmonics of the topographically trapped K_1 tide at the continental slope.

A Study of Samuel Beckett’s “Waiting for Godot”

The theatre of the Absurd includes plays wherein humans are mere puppets full of irrational and illogical thoughts. From Aeschylus to Ibsen, the artists aimed at constructing meaning out of chaos and at gaining a momentary stay at confusion. So drama was then a temporary escape from the utter meaninglessness of life, a brief period when the audiences could dismiss their tensions and enter into a fictional world based on the assumption that man was a rational animal. But, ‘The Theatre of the Absurd’ ruthlessly shattered these notions, advocating instead their view of human being as an isolated existence and to represent life as it moves from nothingness whence it came to nothingness where it must go. The same notion is very much significant in Shakespeare’s line: “Life is a tale told by an idiot Full of sound and fury signifying nothing.” (Act V, Scene 5, Macbeth) Martin Esslin provided justification for the emergence of this new wave in the theatre, in his book: “The Theatre of the Absurd” which attempts to make man face up the world in which he lives and human conditions as they really are. As it was believed that the real dignity of man lies in his ability to face the reality in its senselessness, to accept it freely, without fear, without illusions and to laugh at it. This term is applied to a group of dramatists in the 1950s who shared the same predicament of man in the universe. Incidentally, the word ‘absurd’ is used in music which denotes a ‘jarring note’ or ‘discord’. This research paper is an attempt to study Samuel Beckett’s “Waiting for Godot,” a tragicomedy in two acts, published in 1952, originally in French as En attendant Godot and first produced in 1953. It is a true innovation in drama that successfully depicts the search for meaning in a world of chaos.

Fabry-Pérot optical frequency comb based mm-wave RoF system using pilot-assisted equalizer.

The emergence of the millimeter wave (mm-Wave; 30 GHz to 300 GHz) frequency band holds a lot of promise for addressing the congestion at low frequency in future mobile networks. Among many mm-Wave generation schemes, optical heterodyning is considered one of the most promising approaches due to its scalability and potential for integration on chip. Employing optical frequency combs (OFC) for optical heterodyning alleviates the significant phase distortions/noise introduced by the optical sources. However, any residual phase noise in these systems can deteriorate the transmission performance. Here we demonstrate a high-capacity mm-Wave radio-over-fiber (RoF) system using Fabry-Pérot (FP) laser comb overcoming the typical limitations of this source. The temporal phase perturbation induced by the frequency fluctuation of the FP laser is theoretically analyzed, and then estimated and compensated by a pilot-based phase equalizer. Performance evaluation of the proposed phase equalizer is conducted through experiment and simulation. Enabled by the proposed compensation scheme, ten 200 MHz filtered orthogonal frequency division multiplexing (f-OFDM) signal bands modulated by 16-quadrature amplitude modulation (QAM) are transmitted over 10 km fiber, with the ability to serve multiple users. The transmission of 16-QAM modulated single carrier signals with 2 GBd and 8 Gbps data rate is also performed for comparison, which offers better resilience to phase noise, demonstrating the first commercial Quantum Well FP laser-based optical heterodyning mm-Wave RoF system for both multi-carrier and single carrier signals.

Investigation of multi-stage evaporation and wave multiplicity of two-phase rotating detonation waves fueled by ethanol

In this study, a numerical investigation based on the Eulerian-Lagrangian model is conducted to explore a rotating detonation engine (RDE) fueled by liquid ethanol. The focus is on examining the characteristic phenomena of the two-phase rotating detonation wave (RDW) caused by droplet evaporation and varying inlet conditions. To enhance the evaporation of liquid fuel, pre-heated air is used, and both liquid and pre-vaporized ethanol are simultaneously injected. The distribution of ethanol droplets reveals an initial concentration near the injection surface and accumulation in the fuel-refill zone. Here, liquid droplets gradually evaporate after absorbing latent heat from the surrounding gas. The subsequent interactions between the evaporating droplets and the RDW vary with the droplet size. For droplets with diameters of d0 = 5–15 μm, after being swept by the RDW, a secondary evaporation process occurs, leading to an enlargement of the width of the reaction zone. However, the chemical reactions still predominantly take place in close proximity to the detonation front. As d0 further increases, droplet evaporation persists in the post-detonation expansion zone over a long distance until the remaining droplets are fully evaporated and eventually burned in this region. The study also analyzes the extinction of rotating detonations and the emergence of new detonation waves resulting from local explosions and consequent shock collisions. It is demonstrated that variations in the diameter of injected droplets and inlet temperature can lead to different operating modes with varying numbers of RDWs.