Are fluid inclusions in gypsum reliable paleoenvironmental indicators? An assessment of the evidence from the Messinian evaporites

The paleosalinity of water from which the gypsum precipitated during the Messinian salinity crisis is a controversial issue. Recent microthermometry studies on primary fluid inclusions in gypsum provided very low salinity values not compatible with precipitation from seawater, and suggested strong mixing between seawater and nonmarine waters enriched in calcium sulfate. We applied a new microthermometric protocol on gypsum crystals from nine Mediterranean sections that were experimentally stretched to measure a larger population of fluid inclusions. The results show salinities ranging from 9 to 238 wt‰ NaCl equivalent, largely falling within the evaporation path of normal seawater. The data from previous studies were obtained mostly from those fluid inclusions capable of nucleating a stable bubble after a weak stretching, which probably correspond to those having a lower salinity acquired through post-depositional crack-and-seal processes. Our data suggest instead that the primary gypsum precipitated from a marine brine, later modified by post-trapping processes during tectonics and exhumation.

Spatial distribution of turbulent diapycnal mixing along the Mindanao current inferred from rapid-sampling Argo floats

The Mindanao Current (MC) bridges the North Pacific low-latitude western boundary current system region and the Indonesian Seas by supplying the North Pacific waters to the Indonesian Throughflow. Although the previous study speculated that the diapycnal mixing along the MC might be strong on the basis of the water mass analysis of the gridded climatologic dataset, the real spatial distribution of diapycnal mixing along the MC has remained to be clarified. We tackle this question here by applying a finescale parameterization to temperature and salinity profiles obtained using two rapid-sampling profiling Argo floats that drifted along the MC. The western boundary (WB) region close to the Mindanao Islands and the Sangihe Strait are the two mixing hotspots along the MC, with energy dissipation rate ε and diapycnal diffusivity Kρ enhanced up to ~ 10–6 W kg−1 and ~ 10–3 m2 s−1, respectively. Except for the above two mixing hotspots, the turbulent mixing along the MC is mostly weak, with ε and Kρ to be 10–11–10–9 W kg−1 and 10–6–10–5 m2 s−1, respectively. Strong mixing in the Sangihe Strait can be basically attributed to the existence of internal tides, whereas strong mixing in the WB region suggests the existence of internal lee waves. We also find that water mass transformation along the MC mainly occurs in the Sangihe Strait where the water masses are subjected to strong turbulent mixing during a long residence time.

Second-Order Least Squares Estimation in Nonlinear Time Series Models with ARCH Errors

Many financial and economic time series exhibit nonlinear patterns or relationships. However, most statistical methods for time series analysis are developed for mean-stationary processes that require transformation, such as differencing of the data. In this paper, we study a dynamic regression model with nonlinear, time-varying mean function, and autoregressive conditionally heteroscedastic errors. We propose an estimation approach based on the first two conditional moments of the response variable, which does not require specification of error distribution. Strong consistency and asymptotic normality of the proposed estimator is established under strong-mixing condition, so that the results apply to both stationary and mean-nonstationary processes. Moreover, the proposed approach is shown to be superior to the commonly used quasi-likelihood approach and the efficiency gain is significant when the (conditional) error distribution is asymmetric. We demonstrate through a real data example that the proposed method can identify a more accurate model than the quasi-likelihood method.

Resonant X-ray photo-oxidation of light-harvesting iron (II/III) N-heterocyclic carbene complexes

Two photoactive iron N-heterocyclic carbene complexes $${[\hbox {Fe}^{{{\rm{II}}}}(\hbox {btz})_2(\hbox {bpy})]^{2+}}$$ [ Fe II ( btz ) 2 ( bpy ) ] 2 + and $${[\hbox {Fe}^{{\rm{III}}}(\hbox {btz})_3]^{3+}}$$ [ Fe III ( btz ) 3 ] 3 + , where btz is 3,3’-dimethyl-1,1’-bis(p-tolyl)-4,4’-bis(1,2,3-triazol-5-ylidene) and bpy is 2,2’-bipyridine, have been investigated by Resonant Photoelectron Spectroscopy (RPES). Tuning the incident X-ray photon energy to match core-valence excitations provides a site specific probe of the electronic structure properties and ligand-field interactions, as well as information about the resonantly photo-oxidised final states. Comparing measurements of the Fe centre and the surrounding ligands demonstrate strong mixing of the Fe $${\hbox {t}_{{\rm{2g}}}}$$ t 2 g levels with occupied ligand $$\pi$$ π orbitals but weak mixing with the corresponding unoccupied ligand orbitals. This highlights the importance of $$\pi$$ π -accepting and -donating considerations in ligand design strategies for photofunctional iron carbene complexes. Spin-propensity is also observed as a final-state effect in the RPES measurements of the open-shell $$\hbox {Fe}^{{\rm{III}}}$$ Fe III complex. Vibronic coupling is evident in both complexes, where the energy dispersion hints at a vibrationally hot final state. The results demonstrate the significant impact of the iron oxidation state on the frontier electronic structure and highlights the differences between the emerging class of $$\hbox {Fe}^{{\rm{III}}}$$ Fe III photosensitizers from those of more traditional $$\hbox {Fe}^{{\rm{II}}}$$ Fe II complexes.

CLTs for Dependent Processes

This chapter deals with the central limit theorem (CLT) for dependent processes. As with the law of large numbers, the focus is on near‐epoch dependent and mixing processes and array versions of the results are given to allow heterogeneity. The cornerstone of these results is a general CLT due to McLeish, from which a result for martingales is obtained directly. A result for stationary ergodic mixingales is given, and the rest of the chapter is devoted to proving and interpreting a CLT for mixingales and hence for arrays that are near‐epoch dependent on a strong‐mixing and uniform-mixing processes.

ON OPTIMAL CONTROL OF A STOCHASTIC EQUATION WITH A FRACTIONAL WIENER PROCESS

In recent years, a new direction of research has emerged in the theory of stochastic differential equations, namely, stochastic differential equations with a fractional Wiener process. This class of processes makes it possible to describe adequately many real phenomena of a stochastic nature in financial mathematics, hydrology, biology, and many other areas. These phenomena are not always described by stochastic systems satisfying the conditions of strong mixing, or weak dependence, but are described by systems with a strong dependence, and this strong dependence is regulated by the so-called Hurst parameter, which is a characteristic of this dependence. In this article, we consider the problem of the existence of an optimal control for a stochastic differential equation with a fractional Wiener process, in which the diffusion coefficient is present, which gives more accurate simulation results. An existence theorem is proved for an optimal control of a process that satisfies the corresponding stochastic differential equation. The main result was obtained using the Girsanov theorem for such processes and the existence theorem for a weak solution for stochastic equations with a fractional Wiener process.

LXM: better splittable pseudorandom number generators (and almost as fast)

In 2014, Steele, Lea, and Flood presented SplitMix, an object-oriented pseudorandom number generator (prng) that is quite fast (9 64-bit arithmetic/logical operations per 64 bits generated) and also splittable . A conventional prng object provides a generate method that returns one pseudorandom value and updates the state of the prng; a splittable prng object also has a second operation, split , that replaces the original prng object with two (seemingly) independent prng objects, by creating and returning a new such object and updating the state of the original object. Splittable prng objects make it easy to organize the use of pseudorandom numbers in multithreaded programs structured using fork-join parallelism. This overall strategy still appears to be sound, but the specific arithmetic calculation used for generate in the SplitMix algorithm has some detectable weaknesses, and the period of any one generator is limited to 2 64 . Here we present the LXM family of prng algorithms. The idea is an old one: combine the outputs of two independent prng algorithms, then (optionally) feed the result to a mixing function. An LXM algorithm uses a linear congruential subgenerator and an F 2 -linear subgenerator; the examples studied in this paper use a linear congruential generator (LCG) of period 2 16 , 2 32 , 2 64 , or 2 128 with one of the multipliers recommended by L’Ecuyer or by Steele and Vigna, and an F 2 -linear xor-based generator (XBG) of the xoshiro family or xoroshiro family as described by Blackman and Vigna. For mixing functions we study the MurmurHash3 finalizer function; variants by David Stafford, Doug Lea, and degski; and the null (identity) mixing function. Like SplitMix, LXM provides both a generate operation and a split operation. Also like SplitMix, LXM requires no locking or other synchronization (other than the usual memory fence after instance initialization), and is suitable for use with simd instruction sets because it has no branches or loops. We analyze the period and equidistribution properties of LXM generators, and present the results of thorough testing of specific members of this family, using the TestU01 and PractRand test suites, not only on single instances of the algorithm but also for collections of instances, used in parallel, ranging in size from 2 to 2 24 . Single instances of LXM that include a strong mixing function appear to have no major weaknesses, and LXM is significantly more robust than SplitMix against accidental correlation in a multithreaded setting. We believe that LXM, like SplitMix, is suitable for “everyday” scientific and machine-learning applications (but not cryptographic applications), especially when concurrent threads or distributed processes are involved.

Observed features of the water masses in the Halmahera Sea in November 2016

Halmahera Sea is one of the locations in the eastern route of Indonesian Throughflow (ITF), where high salinity water is mainly transported by the ITF. The description of water mass in the Halmahera Sea from the perspective of water mass, and related mixing is important. It is not only useful for understanding water mass features, but it can also be used to determine the strength of the turbulent mixing, and so allow how it relates to the water transformation. Here, we report the water mass properties and estimation of mixing quantities in the Halmahera Sea from the CTD profiles based on recent onboard observations during the IOCAS cruise in November 2016. The water mass analysis was done by examining the characteristics of water types in the Temperature-Salinity (T-S) diagram. The mixing estimation uses the density profile derived from temperature and salinity profiles and the quantification of vertical turbulence observed by density overturn. Halmahera Sea is to be found as the location where the thermocline salinity changes abruptly, it is shown from the erosion of salinity maximum in the density of 22-26σθ decreased from the north to the south of the basin. It is associated with strong mixing with spots of higher vertical diffusivity in the thermocline and intermediate layer. In the upper layer, the mixed layer depth in the Halmahera Sea is relatively shallow with an average of about 16.95 m and it is associated with weak wind stress during this month.

SEBARAN VERTIKAL TOTAL NITROGEN, TOTAL FOSFAT, DAN AMONIA PADA PERAIRAN PESISIR YANG BERDEKATAN DENGAN KAWASAN BUDIDAYA LAUT DI BALI UTARA

Buangan limbah organik dari kegiatan budidaya ikan berdampak pada naiknya konsentrasi senyawa nitrogen di perairan. Tujuan penelitian ini adalah untuk mengetahui sebaran vertikal konsentrasi total nitrogen (TN), total fosfat (TP), dan amonia pada perairan pesisir yang berdekatan dengan kawasan budidaya ikan laut di Bali Utara. Titik sampling dipilih pada kedalaman 5, 10, 15, 20, dan 30 meter dengan arah tegak lurus garis pantai di kawasan perbenihan ikan dengan tingkat aktivitas tinggi (Desa Gerokgak dan Desa Penyabangan) dan tiga titik sampling di sekitar karamba jaring apung (KJA) di Teluk Kaping, Desa Sumberkima. Sampel air diambil pada bagian permukaan, tengah, dan dasar pada tiap titik sampling. Penelitian ini dilakukan pada tahun 2019 dengan dua periode waktu yaitu bulan April sampai Juni dan Agustus sampai Oktober dengan satu kali pengambilan contoh air setiap bulan. Hasil penelitian menunjukkan bahwa sebaran konsentrasi TN, TP, dan amonia secara vertikal cenderung homogen pada tiap titik pengamatan. Konsentrasi TN, TP, dan amonia selama penelitian berturut-turut adalah 1,2-1,5 mg/L; 0,081-0,090 mg/L; dan 0,054-0,057 mg/L. Nilai tersebut berada di bawah baku mutu air untuk kebutuhan budidaya ikan. Sebaran konsentrasi senyawa nitrogen dan fosfat secara vertikal di lokasi penelitian relatif homogen pada semua lapisan kedalaman air yang diamati. Kondisi tersebut menunjukkan bahwa proses percampuran masa air terjadi secara merata di kawasan tersebut. Kualitas perairan di lokasi penelitian masih sesuai dengan nilai baku mutu untuk kegiatan budidaya laut.Direct discharge of organic waste from aquaculture platforms is likely to increase nitrogen concentration in the surrounding waters. The study aimed to investigate the vertical distribution of total nitrogen (TN), total phosphorus (TP), and ammonia concentration in the coastal waters adjacent to the three densest mariculture sites in North Bali (Gerokgak, Penyabangan, and Kaping Bay). Field surveys were conducted six times within two periods namely April to June and August to October 2019. Samples of different water columns (surface, middle, and bottom) were collected using a Nansen water sampler in each sampling point. The samples were immediately analyzed at the Research Institute for Mariculture and Fishery Extension, Gondol. Total nitrogen, total phosphate, and ammonia were analysed using sulfuric acid destruction and distillation, nitrate-acid destruction, and phenol-spectrophotometer, respectively. The result showed that TN, TP, and ammonia levels were 1.2-1.5 mg/L, 0.081-0.090 mg/L, and 0.054-0.057 mg/L, respectively. The vertical distribution of nitrogen and phosphorus compounds at all layers of water column were relatively homogenous indicating a strong mixing between the seawater layers. Thus, the study concludes that the variations of all water quality parameters are within the water quality standard needed for mariculture activities.