Functional asymmetry and chemical reactivity of CsoR family persulfide sensors

CstR is a persulfide-sensing member of the functionally diverse copper-sensitive operon repressor (CsoR) superfamily that regulates the bacterial response to hydrogen sulfide (H2S) and more oxidized reactive sulfur species (RSS) in Gram-positive pathogens. A cysteine thiol pair on CstR reacts with RSS to form a mixture of interprotomer di-, tri- and tetrasulfide crosslinks, which drives transcriptional derepression of CstR-regulated genes. In some bacteria, notably methicillin-resistant Staphylococcus aureus (MRSA), CstR and CsoR, a Cu(I)-sensor, exhibit no regulatory crosstalk in cells, despite maintaining an identical pair of cysteines. We report a sequence similarity network (SSN) analysis of the entire CsoR superfamily, together with the first crystallographic structure of a CstR protein and mass spectrometry-based kinetic profiling experiments to obtain new insights into the molecular basis of RSS specificity in CstRs. The more N-terminal cysteine is the attacking Cys in CstR and is far more nucleophilic than in a CsoR. This cysteine, C30 in SpCstR, is separated from the resolving thiol, C59′, by an Asn55′ wedge. Chemical reactivity experiments reveal a striking asymmetry of reactivity, preserved in all CstRs and with all oxidants tested; however, the distribution of crosslinked products varies markedly among CstRs. Substitution of N55 with Ala in SpCstR significantly impacts the distribution of species, despite adopting the same structure as the parent repressor. We show that CstRs react with hydrogen peroxide, a finding that contrasts sharply with other structurally distinct persulfide sensors from Gram-negative bacteria. This suggests that other factors may enhance the specificity and repressor activity of CstRs in cells.

Black holes, moduli, and long-range forces

It is well known that an identical pair of extremal Reissner-Nordström black holes placed a large distance apart will exert no force on each other. In this paper, I establish that the same result holds in a very large class of two-derivative effective theories containing an arbitrary number of gauge fields and moduli, where the appropriate analog of an extremal Reissner-Nordström black hole is a charged, spherically symmetric black hole with vanishing surface gravity or vanishing horizon area. Analogous results hold for black branes.

Dislocated quasi cone b-metric space over Banach algebra and contraction principles with application to functional equations

In this paper we introduce dislocated and dislocated quasi version of a cone b-metric space over a Banach algebra as well as weak semi α-admissible and α-identical pair of mappings and prove common fixed point theorems for a pair of α-identical and weak α-admissible mappings in the aforesaid spaces. Our results are supported with suitable examples and an application to a system of m-tupled functional equations.

Image-to-Image Translation Using Identical-Pair Adversarial Networks

We propose Identical-pair Adversarial Networks (iPANs) to solve image-to-image translation problems, such as aerial-to-map, edge-to-photo, de-raining, and night-to-daytime. Our iPANs rely mainly on the effectiveness of adversarial loss function and its network architectures. Our iPANs consist of two main networks, an image transformation network T and a discriminative network D. We use U-NET for the transformation network T and a perceptual similarity network, which has two streams of VGG16 that share the same weights for network D. Our proposed adversarial losses play a minimax game against each other based on a real identical-pair and a fake identical-pair distinguished by the discriminative network D; e.g. a discriminative network D considers two inputs as a real pair only when they are identical, otherwise a fake pair. Meanwhile, the transformation network T tries to persuade the discriminator network D that the fake pair is a real pair. We experimented on several problems of image-to-image translation and achieved results that are comparable to those of some existing approaches, such as pix2pix, and PAN.

Same Jeans, Same Stitch? A Comparison of Denim Production Across Three Factories in Punjab, Pakistan

In this paper, we look at denim production in three different factories in Punjab, Pakistan. We map the manufacturing process for a standard pair of denim jeans produced for an international retailer. We asked three factories of different scales and proximities to the technological frontier to stitch, finish and wash an identical pair of jeans. These firms included a large-scale exporter with established links to a major multinational brand, a medium exporter with links to regional European labels and a small producer selling primarily to the domestic market. Timing the operations ourselves, we find that the stitching time of the large-scale exporter is about one-third less than that of the medium exporter and about half the stitching time of the small firm. Of the three firms, only the large exporter pays wages based strictly on standard minute value – the time expected to complete an operation. The two smaller firms pay piece rates that reflect the market rates paid for individual operations by firms throughout the sector. Even without increases in stitching efficiency, the two smaller firms could reduce their stitching costs by 30–50 percent if they were able to switch to paying wages based on stitching times. We also calculate the labor cost savings that the two smaller firms could accrue by adopting some of the more advanced equipment used by the large exporter, along with lower piece rates. Of these, the most reasonable investment would be in better loop-making machines; the cost of equipment could be recuperated by producing 325,000–500,000 garments, which for the medium firm is four to eight months’ production at current levels. However, piece rates are entrenched and, if sticky, could reduce the incentives for firms to adopt labor-saving technologies.

Synchronization of coupled stick-slip oscillators

A rationale is provided for the emergence of synchronization in a system of coupled oscillators in a stick-slip motion. The single oscillator has a limit cycle in a region of the state space for each parameter set beyond the supercritical Hopf bifurcation. The two-oscillator system that has similar weakly coupled oscillators exhibits synchronization in a parameter range. The synchronization has an anti-phase nature for an identical pair. However, it tends to be more in-phase for a non-identical pair with a rather weak coupling. A system of three identical oscillators (1, 2, and 3) coupled in a line (with two springs k12=k23) exhibits synchronization with two of them (1 and 2 or 2 and 3) being nearly in-phase. These collective behaviours are systematically estimated using the phase reduction method.

The Stabilized Radiometer Platform (STRAP)—An Actively Stabilized Horizontally Level Platform for Improved Aircraft Irradiance Measurements

Measurements of solar and infrared irradiance by instruments rigidly mounted to an aircraft have historically been plagued by the introduction of offsets and fluctuations into the data that are solely due to the pitch and roll movements of the aircraft. The Stabilized Radiometer Platform (STRAP) was developed to address this problem. Mounted on top of an aircraft and utilizing a self-contained, coupled Inertial Navigation System–GPS, STRAP actively keeps a set of uplooking radiometers horizontally level to within ±0.02° for aircraft pitch and roll angles of up to approximately ±10°. The system update rate of 100 Hz compensates for most pitch and roll changes experienced in normal flight and in turbulence. STRAP was mounted on a Twin Otter aircraft and its performance evaluated during normal flight and during a series of flight maneuvers designed to test the accuracy, range, and robustness of the platform. The measurements from an identical pair of solar pyranometers—one mounted on STRAP and the other rigidly mounted nearby directly to the aircraft—are compared to illustrate the accuracy and capability of the new platform. Results show that STRAP can keep radiometers level within the specified pitch and roll range, that it is able to recover from flight maneuvers outside of this range, and that it greatly increases the quantity of useful radiometer data from any given flight. Of particular note, STRAP now allows accurate measurements of the downwelling solar irradiance during spiral ascents or descents of the aircraft, greatly expanding the utility of aircraft radiometer measurements.

Effects of the parental environment on full-sib families of Pinussylvestris

Identical pair crosses, including reciprocals, in Pinussylvestris L. (Scots pine) were made on ramets of the same clones in three clonal archives (seed orchards) in Sweden: Sävar (64°N), Röskär (59.5°N), and Degeberga (56°N). The offspring were used to test the hypothesis that the parental environment could affect the performance of the progeny (aftereffects). Growth and freezing tests were performed in the controlled conditions of the Stockholm Phytotron. Parental environment affected seed weight: the heaviest seeds came from Röskär and the lightest seeds, from Degeberga. Height development was affected in the two growth periods tested: seeds from Sävar produced the shortest plants and seeds from Röskär, the tallest plants. There was an effect on the autumn frost hardiness in the first growth period that disappeared after the second growth period. The most hardy progenies came from Sävar. The aftereffects of the parental environment were less than the maternal effects on seed weight and also less than the effects of full-sib families on growth and autumn frost hardiness. Small but mostly significant reciprocal effects were found for height and height increment during the second growth period. There was a significant reciprocal effect for seed weight. Seed weight differences could explain only a small part of the effects on growth and none of the effects on hardiness.

Triterpene metabolite of Trametes stowardii

The fungus Trametes stowardii produces a triterpenoid metabolite with an uncommon malonate conjugate group. Chemical and spectroscopic evidence indicate the structure (1) (3α-carboxyacetoxy-24ξ-methyl-23- oxolanosta-8,25-dien-27-oic acid) for the triterpene. Both (1) and the recently reported fungal metabolite carboxyacetyl-quercinic acid (6)1 are converted into an identical pair of butenolides (8).