Testing jointly for structural changes in the error variance and coefficients of a linear regression model

We provide a comprehensive treatment for the problem of testing jointly for structural changes in both the regression coefficients and the variance of the errors in a single equation system involving stationary regressors. Our framework is quite general in that we allow for general mixing-type regressors and the assumptions on the errors are quite mild. Their distribution can be non-normal and conditional heteroskedasticity is permitted. Extensions to the case with serially correlated errors are also treated. We provide the required tools to address the following testing problems, among others: a) testing for given numbers of changes in regression coefficients and variance of the errors; b) testing for some unknown number of changes within some pre-specified maximum; c) testing for changes in variance (regression coefficients) allowing for a given number of changes in the regression coefficients (variance); d) a sequential procedure to estimate the number of changes present. These testing problems are important for practical applications as witnessed by interests in macroeconomics and finance where documenting structural changes in the variability of shocks to simple autoregressions or Vector Autoregressive Models has been a concern.First author draf

Automatic variance control and variance estimation loops

A closed loop servo approach is applied to the problem of controlling and estimating variance in nonstationary signals. The new circuit closely resembles but is not the same as, automatic gain control (AGC) which is common in radio and other circuits. The closed loop nature of the solution to this problem makes this approach highly accurate and can be used recursively in real time

Asuhan Keperawatan Abortus Inkomplit Yang Mengalami Masalah Nyeri Dengan Tindakan Teknik Relaksasi Nafas Dalam Di RSU UKI Jakarta

Abortus merupakan penghentian atau berakhirnya suatu kehamilan sebelum usia kehamilan 20 minggu. Salah satu jenis Abortus adalah Abortus Inkomplit dimana terjadi adanya flek, dan sebagian hasil konsepsi telah keluar. Menurut data WHO angka kejadian Abortus adalah 15-25 %, di Indonsia tahun 2012 sebanyak 31 %, sedangkan diRSU UKI periode bulan Januari-Desember 2018 sebanyak 11 pasien (3,43%). Pasien Abortus Inkomplit biasanya mengalami nyeri.Tujuan penelitian untuk melakukan asuhan keperawatan pasienyang mengalami nyeri dengan tindakan teknik relaksasi nafas dalam untuk membantu mengurangi nyeri. Metode studi kasus dengan pendekatan proses keperawatan meliputi wawancara, observasi dan pendokumentasian serta membandingkan tingkat keberhasilan pada 2 pasien. Pemberian asuhan keperawatan pada kedua pasien mulai tanggal 04-31 Maret.Diagnosa keperawatan yang diangkat ialah gangguan rasa nyaman nyeri berhubungan dengan kerusakan jaringan uteri. Setelah dilakukan tindakan asuhan keperawatan selama 3x24 jam yaitu mengobservasi tanda-tanda vital, mengkaji status nyeri (lokasi, karakteristik, frekuensi, skala, waktu dan faktor pencetus), memberikan posisi semi fowler, mengajarkan teknik relaksasi nafas dalam. Hasilpada kedua pasien adalah pasien 1 masalah nyeri teratasi skala nyeri 1, sedangkan pasien 2 teratasi sebagian skala nyeri 3. Kerjasama antar tim kesehatan, keluarga sangat diperlukan untuk keberhasilan asuhan keperawatan pasien Abortus Inkomplit dengan masalah nyeri. Kata kunci: Nyeri, Abortus Inkomplit, Teknik Relaksasi Nafas Dalam. Abortion is the termination or termination of a pregnancy before 20 weeks' gestation. One type of Abortion is incomplete Abortion where there are spots, and some of the results of the conception have come out. According to WHO data the incidence of Abortion is 15-25%, in Indonesia in 2012 as many as 31%, while in the UKSRRU in the January-December 2018 period there were 11 patients (3.43%). Patients with incomplete abortion usually experience pain. The aim of the study is to perform patient nursing care that experiences pain with the relaxation of deep breathing techniques to help reduce pain. The case study method with the nursing process approach includes interviews, observation and documentation as well as comparing the success rates in 2 patients. The provision of nursing care to both patients from March 4 to 31 March. The nursing diagnoses that were raised were discomfort of pain associated with damage to uterine tissue. After 3x24 hours of nursing care actions that are observing vital signs, assessing the pain status (location, characteristics, frequency, scale, time and precipitating factors), giving a semi-fowler position, teaching deep breathing relaxation techniques. The results of the two patients were patient 1, the pain problem was overcome by the pain scale 1, while patient 2 was partially overcome by the pain scale 3. Cooperation between health teams, family was needed for the success of nursing care for the incomplete Abortion patient with the pain problem. Keywords: Pain, incomplete abortion, deep breath relaxation technique

Quantifying cosmic variance

We determine an expression for the cosmic variance of any "normal" galaxy survey based on examination of M* +/- 1 mag galaxies in the SDSS DR7 data cube. We find that cosmic variance will depend on a number of factors principally: total survey volume, survey aspect ratio, and whether the area surveyed is contiguous or comprised of independent sight-lines. As a rule of thumb cosmic variance falls below 10% once a volume of 10^7h_0.7^-3Mpc^3 is surveyed for a single contiguous region with a 1:1 aspect ratio. Cosmic variance will be lower for higher aspect ratios and/or non-contiguous surveys. Extrapolating outside our test region we infer that cosmic variance in the entire SDSS DR7 main survey region is ~7% to z < 0.1. The equation obtained from the SDSS DR7 region can be generalised to estimate the cosmic variance for any density measurement determined from normal galaxies (e.g., luminosity densities, stellar mass densities and cosmic star-formation rates) within the volume range 10^3 to 10^7 h^-3_0.7Mpc^3. We apply our equation to show that 2 sightlines are required to ensure cosmic variance is <10% in any ASKAP galaxy survey (divided into dz ~0.1 intervals, i.e., ~1 Gyr intervals for z <0.5). Likewise 10 MeerKAT sightlines will be required to meet the same conditions. GAMA, VVDS, and zCOSMOS all suffer less than 10% cosmic variance (~3%-8%) in dz intervals of 0.1, 0.25, and 0.5 respectively. Finally we show that cosmic variance is potentially at the 50-70% level, or greater, in the HST Ultra Deep Field depending on assumptions as to the evolution of clustering. 100 or 10 independent sightlines will be required to reduce cosmic variance to a manageable level (<10%) for HST ACS or HST WFC3 surveys respectively (in dz ~ 1 intervals). Cosmic variance is therefore a significant factor in the z>6 HST studies currently underway.Comment: Accepted for publication in MNRA

Cosmology without cosmic variance

We examine the improvements in constraints on the linear growth factor G and its derivative f=d ln G / dln a that are available from the combination of a large-scale galaxy redshift survey with a weak gravitational lensing survey of background sources. In the linear perturbation theory limit, the bias-modulation method of McDonald & Seljak allows one to distinguish the real-space galaxy clustering from the peculiar velocity signal in each Fourier mode. The ratio of lensing signal to galaxy clustering in transverse modes yields the bias factor b of each galaxy subset (as per Pen 2004), hence calibrating the conversion from galaxy real-space density to matter density in every mode. In combination these techniques permit measure of the growth rate f in each Fourier mode. This yields a measure of the growth rate free of sample variance, i.e. the uncertainty in f can be reduced without bound by increasing the number of redshifts within a finite volume. In practice, the gain from the absence of sample variance is bounded by the limited range of bias modulation among dark-matter halos. Nonetheless, the addition of background weak lensing data to a redshift survey increases information on G and f by an amount equivalent to a 10-fold increase in the volume of a standard redshift-space distortion measurement---if the lensing signal can be measured to sub-percent accuracy. This argues that a combined lensing and redshift survey over a common low-redshift volume is a more powerful test of general relativity than an isolated redshift survey over larger volume at high redshift. An example case is that a survey of ~10^6 redshifts over half the sky in the redshift range $z=0.5\pm 0.05$ can determine the growth exponent \gamma for the model $f=\Omega_m^\gamma$ to an accuracy of $\pm 0.015$, using only modes with k<0.1h/Mpc, but only if a weak lensing survey is conducted in concert. [Abridged]Comment: 9 pages, 3 figures, accepted by MNRAS, minor changes to match the accepted versio

A Cosmic Variance Cookbook

Deep pencil beam surveys (<1 deg^2) are of fundamental importance for studying the high-redshift universe. However, inferences about galaxy population properties are in practice limited by 'cosmic variance'. This is the uncertainty in observational estimates of the number density of galaxies arising from the underlying large-scale density fluctuations. This source of uncertainty can be significant, especially for surveys which cover only small areas and for massive high-redshift galaxies. Cosmic variance for a given galaxy population can be determined using predictions from cold dark matter theory and the galaxy bias. In this paper we provide tools for experiment design and interpretation. For a given survey geometry we present the cosmic variance of dark matter as a function of mean redshift z and redshift bin size Dz. Using a halo occupation model to predict galaxy clustering, we derive the galaxy bias as a function of mean redshift for galaxy samples of a given stellar mass range. In the linear regime, the cosmic variance of these galaxy samples is the product of the galaxy bias and the dark matter cosmic variance. We present a simple recipe using a fitting function to compute cosmic variance as a function of the angular dimensions of the field, z, Dz and stellar mass m*. We also provide tabulated values and a software tool. We find that for GOODS at z=2 and with Dz=0.5 the relative cosmic variance of galaxies with m*>10^11 Msun is ~38%, while it is ~27% for GEMS and ~12% for COSMOS. For galaxies of m*~10^10 Msun the relative cosmic variance is ~19% for GOODS, ~13% for GEMS and ~6% for COSMOS. This implies that cosmic variance is a significant source of uncertainty at z=2 for small fields and massive galaxies, while for larger fields and intermediate mass galaxies cosmic variance is less serious.Comment: 8 pages, 4 figures, 5 tables, submitted to Ap