PENGARUH BRACING PADA BANGUNAN BERTINGKAT RANGKA BAJA YANG BERDIRI DI ATAS TANAH MIRING TERHADAP GEMPA

Kolom pada bagian bawah struktur bangunan yang menopang bangunan pada tanah miring memiliki ketinggian yang berbeda. Kerusakan sering ditemui pada kolom pendek. Hal itu disebabkan adanya selisih yang besar dalam distribusi gaya untuk kolom pendek dan kolom panjang. Distribusi gaya dengan selisih yang besar tersebut menyebabkan struktur tidak stabil saat menerima beban sehingga perlu dihindari. Salah satu cara yang dapat dilakukan adalah mengkombinasikan struktur dengan bracing (elemen pengaku portal). Penelitian dilakukan dengan pemodelan struktur bangunan rangka baja yang terdiri dari 10 lantai yang berdiri di atas tanah dengan kemiringan 12,5  dan dilakukan variasi penempatan bracing yang akan ditempatkan bertahap dari lantai dasar sampai lantai 9 sisi luar struktur. Analisis dilakukan dengan alat bantu ETABS 2016. Respons struktur yang ditinjau adalah simpangan struktur, gaya geser dasar dan gaya geser pada kolom tingkat pertama struktur.Hasil analisis menunjukkan bahwa pemodelan struktur bangunan yang berdiri di atas tanah miring dengan pemasangan bracing pada lantai dasar (Model B) menghasilkan gaya geser pada kolom pendek paling kecil jika dibandingkan dengan pemodelan lainnya. Respons struktur yang dihasilkan oleh Model B seperti periode struktur, displacement dan simpangan antar tingkat juga telah memenuhi persyaratan yang ada. Kata Kunci: Bangunan Bertingkat, Baja, Tanah Miring, Bracing, Kolom Pende

Abundance analysis of a nitrogen-rich extreme-helium hot subdwarf from the SALT survey

We have performed a detailed spectral analysis of the helium-rich hot subdwarf EC 20187-4939 using data obtained in the SALT survey of helium-rich hot subdwarfs. We have measured its effective temperature, surface gravity and chemical abundances from the spectrum. Its radius has also been determined by fitting the spectral energy distribution using photometric data, from which a mass of 0.44 Msun has been inferred using the measurement of surface gravity. This star is particularly abundant in helium and nitrogen, whilst being both carbon and oxygen-weak. The surface abundances and mass have been found to be consistent with a helium white dwarf merger product. The abundance effects of alpha captures on nitrogen during the merger process and possible connections between EC 20187-4939 and other carbon-weak related objects are discussed.Comment: 10 pages, 5 figures, 5 tables, accepted for publication in MNRA

Determining the Hubble Constant without the Sound Horizon: A 3.6%3.6\% Constraint on H0H_0 from Galaxy Surveys, CMB Lensing and Supernovae

Many theoretical resolutions to the so-called "Hubble tension" rely on modifying the sound horizon at recombination, $r_s$, and thus the acoustic scale used as a standard ruler in the cosmic microwave background (CMB) and large scale structure (LSS) datasets. As shown in a number of recent works, these observables can also be used to compute $r_s$-independent constraints on $H_0$ by making use of the horizon scale at matter-radiation equality, $k_{\rm eq}$, which has different sensitivity to high redshift physics than $r_s$. In this work, we present the tightest $k_{\rm eq}$-based constraints on the expansion rate from current data, finding $H_0=64.8^{+2.2}_{-2.5}$ at 68$\%$ CL from a combination of BOSS galaxy power spectra, Planck CMB lensing, and the newly released Pantheon+ supernova constraints, as well as physical priors on the baryon density, neutrino mass, and spectral index (in $\mathrm{km}\,\mathrm{s}^{-1}\mathrm{Mpc}^{-1}$ units). The BOSS and Planck measurements have different degeneracy directions, leading to the improved combined constraints, with a bound of $H_0 = 67.1^{+2.5}_{-2.9}$ ($63.6^{+2.9}_{-3.6}$) from BOSS (Planck) alone. The results show some dependence on the neutrino mass bounds, with the constraint broadening to $H_0 = 68.0^{+2.9}_{-3.2}$ if we instead impose a weak prior on $\sum m_\nu$ from terrestrial experiments rather than assuming $\sum m_\nu<0.26\,\mathrm{eV}$, or shifting to $H_0 = 64.6\pm2.4$ if the neutrino mass is fixed to its minimal value. Even without any dependence on the sound horizon, our results are in $\approx 3\sigma$ tension with those obtained from the Cepheid-calibrated distance ladder, providing evidence against new physics models that vary $H_0$ by changing acoustic physics or the expansion history immediately prior to recombination.Comment: 11 pages, 3 figures, submitted to Phys. Rev.

Genarris: Random Generation of Molecular Crystal Structures and Fast Screening with a Harris Approximation

We present Genarris, a Python package that performs configuration space screening for molecular crystals of rigid molecules by random sampling with physical constraints. For fast energy evaluations Genarris employs a Harris approximation, whereby the total density of a molecular crystal is constructed via superposition of single molecule densities. Dispersion-inclusive density functional theory (DFT) is then used for the Harris density without performing a self-consistency cycle. Genarris uses machine learning for clustering, based on a relative coordinate descriptor (RCD) developed specifically for molecular crystals, which is shown to be robust in identifying packing motif similarity. In addition to random structure generation, Genarris offers three workflows based on different sequences of successive clustering and selection steps: the "Rigorous" workflow is an exhaustive exploration of the potential energy landscape, the "Energy" workflow produces a set of low energy structures, and the "Diverse" workflow produces a maximally diverse set of structures. The latter is recommended for generating initial populations for genetic algorithms. Here, the implementation of Genarris is reported and its application is demonstrated for three test cases

Managing pregnancy of unknown location based on initial serum progesterone and serial serum hCG: development and validation of a two-step triage protocol.

A uniform rationalized management protocol for pregnancies of unknown location (PUL) is lacking. We developed a two-step triage protocol based on presenting serum progesterone (step 1) and hCG ratio two days later (step 2) to select PUL at high-risk of ectopic pregnancy (EP).Cohort study of 2753 PUL (301 EP), involving a secondary analysis of prospectively and consecutively collected PUL at two London-based university teaching hospitals. Using a chronological split we used 1449 PUL for development and 1304 for validation. We aimed to select PUL as low-risk with high confidence (high negative predictive value, NPV) while classifying most EP as high-risk (high sensitivity). The first triage step selects low-risk PUL at presentation using a serum progesterone threshold. The remaining PUL are triaged using a novel logistic regression risk model based on hCG ratio and initial serum progesterone (second step), defining low-risk as an estimated EP risk <5%.On validation, initial serum progesterone ≤2nmol/l (step 1) selected 16.1% PUL as low-risk. Second step classification with the risk model M6P selected an additional 46.0% of all PUL as low-risk. Overall, the two-step protocol classified 62.1% of PUL as low-risk, with an NPV of 98.6% and a sensitivity of 92.0%. When the risk model was used in isolation (i.e. without the first step), 60.5% of PUL were classified as low-risk with 99.1% NPV and 94.9% sensitivity.The two-step protocol can efficiently classify PUL into being at high or low risk of complications

Procedural justice, compliance with the law and police stop-and-search: a study of young people in England and Scotland

The policing of young people, especially through stop-and-search, has been rigorously debated in the context of rising violence in the UK. While concepts based on procedural justice theory and perceptions of police fairness are directly relevant to these debates, these have rarely been tested on young people, nor have they taken account of the impact of stop-and-search. This paper examines young people’s experiences of stop-and-search in two Scottish and two English cities, and tests the relationship between these experiences, their trust in the police, their perceptions of police legitimacy and their compliance with the law. The study finds that Scottish adolescents, who experienced higher volume stop-and-search, had more negative attitudes to the police and perceived them to be less procedurally fair than English adolescents. Structural equation modelling confirms that principles of procedural justice theory do apply to young people in this UK sample. However, our findings suggest that stop-and-search may damage trust in the police and perceptions of police legitimacy, regardless of the volume of police stop-and-search, and this may result in increased offending behaviour. With ongoing calls to increase the use of stop-and-search in response to recent increases in knife crime in England, we argue that its use needs to be carefully balanced against the, as yet poorly evidenced, benefits of the use of the tactic

Estimated Exposure Risks from Carcinogenic Nitrosamines in Urban Airborne Particulate Matter

Organic nitrogen (ON) compounds are present in atmospheric particulate matter (PM), but compared to their inorganic, hydrocarbon and oxygenated counterparts, they are difficult to characterize due to their complex chemical composition. Nitrosamines are a class of ON compounds known to be highly carcinogenic, and include species formed from nicotine degradation, but there are no detailed estimates of their abundance in ambient air. We use a highly sensitive analytical method, which is capable of separating over 700 ON compounds, to determine daily variability in nicotine, and 8 non specific and 4 tobacco specific nitrosamines in ambient PM from central London over two periods in winter and summer. The average total nitrosamine concentration was 5.2 ng m-3, substantially exceeding a current public recommendation of 0.3 ng m-3 on a daily basis. The lifetime cancer risk from nitrosamines in urban PM exceeded the U.S. Environmental Protection Agency guideline of 1 excess cancer cases per 1 million population exposed after 1 hour of exposure to observed concentrations per day over the duration of an adult lifetime. A clear relationship between ambient nitrosamines and total PM2.5 was observed with 1.2 ng m-3 ± 2.6 ng m-3 (total nitrosamine) per 10 µg m-3 PM2.5