Sinking flux of particulate organic matter in the oceans: Sensitivity to particle characteristics

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Omand, M. M., Govindarajan, R., He, J., & Mahadevan, A. Sinking flux of particulate organic matter in the oceans: Sensitivity to particle characteristics. Scientific Reports, 10(1), (2020): 5582, doi:10.1038/s41598-020-60424-5.The sinking of organic particles produced in the upper sunlit layers of the ocean forms an important limb of the oceanic biological pump, which impacts the sequestration of carbon and resupply of nutrients in the mesopelagic ocean. Particles raining out from the upper ocean undergo remineralization by bacteria colonized on their surface and interior, leading to an attenuation in the sinking flux of organic matter with depth. Here, we formulate a mechanistic model for the depth-dependent, sinking, particulate mass flux constituted by a range of sinking, remineralizing particles. Like previous studies, we find that the model does not achieve the characteristic ‘Martin curve’ flux profile with a single type of particle, but instead requires a distribution of particle sizes and/or properties. We consider various functional forms of remineralization appropriate for solid/compact particles, and aggregates with an anoxic or oxic interior. We explore the sensitivity of the shape of the flux vs. depth profile to the choice of remineralization function, relative particle density, particle size distribution, and water column density stratification, and find that neither a power-law nor exponential function provides a definitively superior fit to the modeled profiles. The profiles are also sensitive to the time history of the particle source. Varying surface particle size distribution (via the slope of the particle number spectrum) over 3 days to represent a transient phytoplankton bloom results in transient subsurface maxima or pulses in the sinking mass flux. This work contributes to a growing body of mechanistic export flux models that offer scope to incorporate underlying dynamical and biological processes into global carbon cycle models.We thank NSF (OCE 1260080), NASA (NNX16AR48G), and the Ministry of Earth Sciences, Government of India (Monsoon Mission Project on the Bay of Bengal) for support. This work was largely done in 2012 while MMO was a postdoctoral associate at WHOI, during a visit by RG supported by The Mary Sears visiting scholar program to the Woods Hole Oceanographic Institution. Thanks also to Benjamin Hodges for many thoughtful contributions

Novel black hole bound states and entropy

We solve for the spectrum of the Laplacian as a Hamiltonian on $\mathbb{R}^{2}-\mathbb{D}$ and in $\mathbb{R}^{3}-\mathbb{B}$. A self-adjointness analysis with $\partial\mathbb{D}$ and $\partial\mathbb{B}$ as the boundary for the two cases shows that a general class of boundary conditions for which the Hamiltonian operator is essentially self-adjoint are of the mixed (Robin) type. With this class of boundary conditions we obtain "bound state" solutions for the Schroedinger equation. Interestingly, these solutions are all localized near the boundary. We further show that the number of bound states is finite and is in fact proportional to the perimeter or area of the removed \emph{disc} or \emph{ball}. We then argue that similar considerations should hold for static black hole backgrounds with the horizon treated as the boundary.Comment: 13 pages, 3 figures, approximate formula for energy spectrum added at the end of section 2.1 along with additional minor changes to comply with the version accepted in PR

Repellent properties of Pithecellobium dulce (Roxb.) Benth. (Family: Fabaceae) against fi lariasis vector, Culex quinquefasciatus Say (Diptera: Culicidae)

To determine the repellent activity of hexane, ethyl acetate, benzene, chloroform, and methanol extract ofPithecellobium dulce leaf and seed against filariasis vector, Culex quinquefasciatus. Evaluation was carried outin a net cage (45 cm2 × 30 cm2 × 25 cm2) containing 100 blood starved female mosquitoes of three mosquitospecies and were assayed in the laboratory condition by using the protocol of WHO: The plant leaf crude extractsof P. dulce was applied at 1.0, 2.5, and 5.0 mg/cm2 separately in the exposed area of the fore arm. Only ethanolserved as control. In this observation, the plant crude extracts gave protection against mosquito bites withoutany allergic reaction to the test person, and also, the repellent activity is dependent on the strength of the plantextracts. Among the tested solvents, both the leaf and seed methanol extracts showed maximum efficacy. Thehighest concentration of 5.0 mg/cm2 provided over 120 min and 90 min protection for the leaf and seed extracts,respectively. From the results, it can be concluded the crude extract of P. dulce was potential for controllingfilariasis vector, C. quinquefasciatus mosquito

A theoretical quantum study of the electronic properties of mentoxy dichloro phosphorous (C10H19OPCl2)

Indexación: Scopus.A theoretical quantum study of the organophosphorus compound with formula C10H19OPCl2 (MEPCL2) was carried out. The results of the calculations show excellent agreement between experimental and computed frequencies evaluated at the B3LYP/6-311++G(d,p) level of theory. A study of the electronic properties, such as excitation energies and wavelengths were performed employing the time-dependent DFT (TD-DFT) method. Global a chemical reactivity of MEPCL2 was analyzed through global reactivity descriptors, while its local reactivity was analyzed by mean maps of the electrostatic potential. Also, the orbital energies values suggest that a charge transfer is occurring within the molecule. © 2018 American Physical Society.https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072018000103887&lng=en&nrm=iso&tlng=e

Genus Zero Correlation Functions in c<1 String Theory

We compute N-point correlation functions of pure vertex operator states(DK states) for minimal models coupled to gravity. We obtain agreement with the matrix model results on analytically continuing in the numbers of cosmological constant operators and matter screening operators. We illustrate this for the cases of the $(2k-1,2)$ and $(p+1,p)$ models.Comment: 11 pages, LaTeX, IMSc--92/35. (revised) minor changes plus one reference adde

Comparative study of surgical results between total abdominal hysterectomy and total laparoscopic hysterectomy in a tertiary hospital: a 2 year retrospective study

Background: Since the introduction of Laparoscopic hysterectomy by Reich in 1989, it has become a widely accepted technique worldwide. The aim of the study was to compare the surgical results between Total Laparoscopic Hysterectomy (TLH) and Total Abdominal Hysterectomy (TAH).Methods: We conducted a retrospective study at Women’s center and hospitals between June 2014 to May 2016, 32 patients who underwent TAH and 55 patients who underwent TLH, were included.Results: We observed that there was no significant difference between the two groups in respect to patient's demographic characteristics, indication of surgery, uterine size, or with history of previous pelvic surgery. Duration of surgery was found to be longer in TLH than TAH (124±39.7 min vs. 104.7±39.8 min). The length of hospital stay was less in TLH than TLH (P-0.0001) and the amount of blood loss were also less in TLH than TAH (103±149 ml versus 243±210 ml). There was no significant difference in view of intra and post operative complications. Hemoglobin change was statistically significant and is more with TAH than TLH (1.57±0.7g% versus 1.12±0.7g%).Conclusions: This study showed that TLH can be safely performed by the experienced surgeon in order to reduce the blood loss, duration of hospital stay and the quality of life

Preface - Personal perspectives in nonlinear science : Looking back, looking forward

Peer reviewedPublisher PD