New photometric studies for two deep, low-mass ratio overcontact binaries: Y Sex and V1363 Ori

We present new photometry for two contact binaries, Y Sex and V1363 Ori, which were observed by three small telescopes in China. By using the W-D method, the absolute parameters are updated from new BVR light curves and previous radial velocity curves. Results identify that two binaries are deep, low-mass ratio (DLMR) overcontact binaries with q ⩽ 0.25 and f ⩾ 50%. From the temperature-luminosity diagram, the primary components are slightly evolved main-sequence stars, whose evolutionary ages are ∼2.51 Gyr for Y Sex and ∼3.56 Gyr for V 1363 Ori, respectively. From the (O − C) curves, it is found that the orbital periods may be undergoing secular increase with cyclic variations, which may be interpreted either by magnetic activity cycles or by the light-time orbit effect. With period increasing, this kind of DLMR overcontact binaries, such as Y Sex and V1363 Ori, will evolve into the rapid-rotating single stars.

Impact of low reactivity fuel type on low load combustion, emissions, and cyclic variations of diesel-ignited dual fuel combustion

In this study, cyclic variations in dual fuel combustion with diesel ignition of three different low reactivity fuels (methane, propane, and gasoline) are examined under identical operating conditions. Experiments were performed on a single cylinder research engine (SCRE) at a low load of 3.3 bar brake mean effective pressure (BMEP). The start of injection (SOI) of diesel was varied from 280 to 330 absolute crank angle degrees (CAD). Engine speed, rail pressure, and boost pressure were held constant at 1500 rpm, 500 bar, and 1.5 bar, respectively. The energy substituted by the low reactivity fuel was fixed at 80% of the total energy input. It was found that diesel-methane (DM) and diesel-propane (DP) combustion were affected by diesel mixing to a greater extent than diesel-gasoline (DG) combustion due to the higher reactivity of gasoline. The magnitude of low temperature heat release was greatest for DG combustion followed by DM and DP combustion for all SOIs. The ignition delay for DG combustion was the shortest, followed by DM and DP combustion. DM and DP combustion exhibited more cyclic variations than DG combustion. Cyclic variations decreased for DM and DP combustion when SOI was advanced; however, DG combustion cyclic variations remained essentially constant for all SOIs. Earlier SOIs (280, 290, 300, and 310 CAD) for DM and (280, 290, and 300 CAD) for DP combustion indicated some prior-cycle effects on the combustion and IMEP (i.e. some level of determinism).

Linking Zoonosis Emergence to Farmland Invasion by Fluctuating Herbivores: Common Vole Populations and Tularemia Outbreaks in NW Spain

The expansion and intensification of agriculture are driving profound changes in ecosystems worldwide, favoring the (re)emergence of many human infectious diseases. Muroid rodents are a key host group for zoonotic infectious pathogens and frequently invade farming environments, promoting disease transmission and spillover. Understanding the role that fluctuating populations of farm dwelling rodents play in the epidemiology of zoonotic diseases is paramount to improve prevention schemes. Here, we review a decade of research on the colonization of farming environments in NW Spain by common voles (Microtus arvalis) and its public health impacts, specifically periodic tularemia outbreaks in humans. The spread of this colonizing rodent was analogous to an invasion process and was putatively triggered by the transformation and irrigation of agricultural habitats that created a novel terrestrial-aquatic interface. This irruptive rodent host is an effective amplifier for the Francisella tularensis bacterium during population outbreaks, and human tularemia episodes are tightly linked in time and space to periodic (cyclic) variations in vole abundance. Beyond the information accumulated to date, several key knowledge gaps about this pathogen-rodent epidemiological link remain unaddressed, namely (i) did colonizing vole introduce or amplified pre-existing F. tularensis? (ii) which features of the “Francisella—Microtus” relationship are crucial for the epidemiology of tularemia? (iii) how virulent and persistent F. tularensis infection is for voles under natural conditions? and (iv) where does the bacterium persist during inter-epizootics? Future research should focus on more integrated, community-based approaches in order to understand the details and dynamics of disease circulation in ecosystems colonized by highly fluctuating hosts.

The statistical characteristics of knock signal waveforms

Individual instances of the knock resonant response are easy to acquire but these are subject to noise and vary considerably from cycle to cycle due to random variations in the knock process. This work provides a new way to quantify and model the stochastic properties of knock signals, capturing both the time domain resonant characteristics within a cycle as well as the random variations from cycle to cycle. A new phase alignment method enables the ensemble mean knock waveform to be identified from the data which also removes noise components without the need for narrowband filtering. This ensemble waveform shows the empirical characteristics of knock onset, decay, and frequency slurring within the cycle as the gas expands and cools. The phase-aligned cyclic variations of the knock waveform are also shown to approximate a (time-varying) dual-Gaussian distribution, and fitting such a model to the data enables the statistical properties of the dataset as a whole to be decomposed into separate knocking and non-knocking populations providing further insight into the knock process. The technique is applied both to filtered cylinder pressure signals and to accelerometer-based knock signals, and the results are compared and contrasted.

Eclipsing Binary Systems XZ Per and BO Vul with Complex Variations in Orbital Periods

The variations in the orbital periods of the eclipsing binary systems XZ Per and BO Vul have been studied. It has been shown that the variations in the orbital period of the eclipsing binary XZ Per are equally well represented as a superposition of the secular decrease and cyclic variations or as a sum of two cyclic variations. In the first case, the monotonic component can be a consequence of the loss of angular momentum by the system due to magnetic braking, while cyclic variations can be explained by the presence of a third body in the system or by the magnetic activity of the secondary component with a convective shell. In the second case, it is possible to assume the presence of two additional bodies in the system, or to attribute one of the period oscillations to the light-time effect, and the other to the magnetic activity of the secondary component. The variations in the orbital period of the eclipsing binary system BO Vul can be represented as a superposition of the secular decrease and cyclic variations. The observed cyclic variations in the period can occur due to the presence of a third body in the system or due to the magnetic activity of the secondary component with a convective shell.

A Simple Algorithm is Created for Identifying Intermenstrual Intervals Containing an Oscillatory LH Pattern That Associates With Vasomotor Symptoms Using Daily Urinary LH Excretion in the Study of Women’s Health Across the Nation (SWAN)

Background: A specific and unique pattern of luteinizing hormone (LH) excretion has been associated with vasomotor symptoms (VMS) in early menopausal women. Described as “oscillations” of LH excretion, this pattern is consistent with secretory “surges” of LH followed by pituitary “fatigue”. This pattern has not been observed in non-VMS intermenstrual intervals and supports the concept that a breakdown in the hypothalamic-pituitary ovarian axis feed-back loops leads to extreme and cyclic variations in gonadotropin hormone releasing hormone (GnRH) secretion that stimulates collateral nerves to alter core body temperature. Regardless of the precise mechanism, the pattern of LH secretion, as transduced in daily urine as oscillations, provides the basis for the development and validation of a VMS algorithm. Objective: The purpose of this study was to create a simple algorithm to identify intermenstrual intervals exhibiting oscillatory LH, to facilitate investigations into its associations with VMS and other symptoms during the menopausal transition (MT). Methods: As part of the Study of Women’s Health Across the Nation (SWAN), participants in the Daily Hormone Substudy (DHS) were asked to provide daily urine samples - from which LH, E1c, and PdG were measured - and complete a daily symptoms diary for one menstrual cycle (up to 50 days). Analyses included 144 participants whose first DHS collection did not meet the Kassam criterion for evidence of luteal activity; of these, 61 were assessed by an expert as having oscillatory LH and 83 as non-oscillatory LH. Proposed algorithm-based classifications regarding oscillatory LH included number of days with LH at least 50% of the collection maximum LH (number of large-LH days) and number of days with LH no more than twice the collection minimum LH (number of small-LH days). Agreement of these 2 criteria with rater-assigned oscillatory LH was assessed using nonparametric t-tests and binomial logistic regression. Associations of these with VMS frequency were assessed using Spearman correlations. Results: The number of large-LH days was strongly associated with oscillatory LH: median (interquartile range) = 13 (7,22) for oscillatory collections versus 4 (2, 11) for non-oscillatory collections (p<.0001) but number of small-LH days was unrelated (p=.98). Percentage of collection days with VMS was significantly correlated with number of large-LH days (Spearman r=.37, p<.0001) but not with number of small-LH days (Spearman r=.03, p>.05); adjustment for total collection length had negligible impact. Conclusion: A simple algorithm using urinary LH profiles can be used to identify intermenstrual collections that likely contain intervals of VMS.

Utilisation of Chemical Waste Additives with Low Octane Commercial Gasoline Fuel to Enhance the Performance of SI Engines

In this study, fusel oil additive from the waste product has been used as an octane number enhancer to improve gasoline engine performance. The fusel additive was added at 10%, 20% and 30% ratios to prepare the investigated fuel samples (M10, M20 and M30, respectively, in addition to pure gasoline M0). Engine tests were conducted at constant half engine load and increasing speed from 1500 rpm to 4500 rpm at 1000 rpm increments. Response surface methodology has been used as a statistical technique to describe the relationship between the investigated input variables with their responses to achieve the optimum operating conditions. Engine cyclic variations were analysed using wavelet analysis of in-cylinder pressure based on indicated mean effective pressure (IMEP) calculated for 100 consecutive cycles. The results showed that the higher brake power was obtained with blended fuel M20 during the engine operating speeds. The maximum increase of brake power found to be 23.6% with M20 compared to gasoline at 1500 rpm, which accompanied by a 7.3% increase in brake specific fuel consumption. On the other hand, the highest increase in brake thermal efficiency is found to be related to the engine speed and fusel additive ratio. Wavelet analysis shows that the engine cyclic variations decrease as the fusel additive introduce with gasoline. Moreover, fusel additive has a pronounced effect on decreasing the cycle to cycle variations of the IMEP time series with the lowest overall engine cyclic variations for M30. Accordingly, 20% fusel additive (M20) can be considered as a valuable octane enhancer for better engine performance.

Detection of period variations of eclipsing binaries in the Catalina Sky Survey

ABSTRACT We present 126 eclipsing binary candidates among 4683 Catalina Sky Surveys (CSS) detached and semi-detached eclipsing binary systems (EBs) showing cyclic or quadratic period variations over a 12 yr time span. By using inverse Gaussian profiles of the eclipses coupled with a Markov chain Monte Carlo procedure, times of minima (ToM) were calculated and diagrams with eclipse timing variations (ETVs) were constructed. Numerical tests were performed, involving synthetic EBs with period variations generated by the PHOEBE 2.0 engine and actual data for EBs with well-known period variations from the literature, to verify that the calculation of ToM variations for our CSS systems is reliable. A total of 63 out of the 126 EBs show likely cyclic ETVs, while the remainder present quadratic behaviour instead. Periods, amplitudes, period change rates, and associated errors were determined by using sinusoidal and parabolic models. 12 out of the 63 EBs (19 per cent) that appear to exhibit periodic ETVs are low-mass candidates. Additionally, four out of 126 also have maximum quadrature light variations. The possibility that the cyclic variations are caused by the light traveltime effect due to the presence of a tertiary companion is investigated. The possible nature of the quadratic ETVs is also discussed.