On: “Variations of Vertical Gravity Gradient in New York City and Alpine, New Jersey” by John T. Kuo, Mario Ottaviani, and Shri K. Singh (GEOPHYSICS, April 1969, p. 235–248).

Geophysics ◽  
1970 ◽  
Vol 35 (3) ◽  
pp. 521-522 ◽  
Author(s):  
Stephen Thyssen-Bornemisza
Keyword(s):  
New York ◽  
New York City ◽  
New Jersey ◽  
York City ◽  
Vertical Gradient ◽  
Gravity Gradient ◽  
Vertical Gravity Gradient ◽  
Vertical Gravity

In their paper, Kuo et al, following the footsteps of Hammer (1938), reported interesting vertical gradient observations in high buildings with a gravity meter. However, conclusion (5) drawn by Kuo et al should be discussed briefly in order to avoid an incorrect impression.

VARIATIONS OF VERTICAL GRAVITY GRADIENT IN NEW YORK CITY AND ALPINE, NEW JERSEY

Geophysics ◽  
1969 ◽  
Vol 34 (2) ◽  
pp. 235-248 ◽  
Author(s):  
John T. Kuo ◽  
Mario Ottaviani ◽  
Shri K. Singh
Keyword(s):  
New York ◽  
New York City ◽  
New Jersey ◽  
York City ◽  
Gravity Data ◽  
Tall Buildings ◽  
Base Station ◽  
Absolute Gravity ◽  
Gravity Gradient ◽  
Vertical Gravity Gradient

Careful gravity measurements with La Coste‐Romberg geodetic gravimeters were carried out in tall buildings on a floor‐to‐floor basis in New York City and on the Armstrong Tower, Alpine, New Jersey. Corrections for the instrumental drift and tidal gravity variation and for the Bouguer effect, topography, mass of the buildings, and subway and basement excavations have been applied to the gravity data, which are tied to the absolute gravity value of the National Gravity Base Station of Washington, D. C. The observed gravity versus elevation curves are nonlinear, particularly near the surface of the ground; the slope of the observed gravity anomaly versus elevation curves reverses sign at an elevation of about 170 ft for the campus buildings and about 350 ft for the downtown buildings, and is nearly linear without a reversal for the Armstrong Tower. The vertical gradients vary substantially even within short distances. Comparisons of the corrected observed gradients with the theoretical gradients of gravity are made. The anomalous gradient anomalies are positive and are correlated with the positive isostatic surface gravity anomalies. Calibration of gravimeters against the observed vertical gradient of gravity to an accuracy of ±2 μgal is definitely feasible provided the gradient is predetermined to a comparable accuracy by a standard instrument.

Freedom of the Air in the United States

1931 ◽  
Vol 25 (2) ◽  
pp. 238-251
Author(s):  
Blewett Lee
Keyword(s):  
United States ◽  
New York ◽  
New York City ◽  
New Jersey ◽  
York City ◽  
The United States ◽  
The State ◽  
Inland Waters ◽  
State Board

On September 15, 1930, the State Board of Commerce and Navigation of New Jersey made a ruling that aircraft would not be permitted to land on any New Jersey waters above tidewater within the jurisdiction of the state. The application had been made for permission to operate a five passenger flying boat between Nolan's Point, Lake Hopatcong, a vacation resort, and New York City, and to set off a portion of the lake to make a landing place for the hydroairplane. It was stated that other inland waters in New Jersey were being used for a similar purpose, and the ground of the refusal was that aircraft flying from water constituted a menace to surface navigation. This ruling created considerable newspaper comment and aroused vigorous protest from persons interested in aviation, and by order of October 20, 1930, the ruling was limited to Lake Hopatcong.

VERTICAL GRADIENT OF GRAVITY ON AXIS FOR HOLLOW AND SOLID CYLINDERS

Geophysics ◽  
1966 ◽  
Vol 31 (4) ◽  
pp. 816-820 ◽  
Author(s):  
Thomas A. Elkins
Keyword(s):  
Hollow Cylinder ◽  
Sudden Change ◽  
Vertical Gradient ◽  
Outer Radius ◽  
Gravity Gradient ◽  
Gradient Effect ◽  
Vertical Gravity Gradient ◽  
Vertical Gravity ◽  
Special Case ◽  
Vertical Gradient Of Gravity

The recent interest in borehole gravimeters and vertical gravity gradient meters makes it worthwhile to analyze the simple case of the vertical gravity gradient on the axis of a hollow cylinder, simulating a borehole. From the viewpoint of potential theory the results are interesting because of the discontinuities which may occur when a vertical gradient profile crosses a sudden change in density. Formulas for the vertical gradient effect are given for observations above, inside, and below a hollow cylinder and a solid cylinder. The special case of an infinitely large outer radius for the cylinders is also considered, leading to formulas for the vertical gradient effect inside a borehole on its axis and inside a horizontal slab. Some remarks are made on the influence of the shape of a buried vertical gradient meter on the correction factor for changing the meter reading to density.

On: “Gravity vertical gradient measurements for the detection of small geologic and anthropogenic forms” by Z. J. Fajklewicz (GEOPHYSICS, October 1976, p. 1016–1030)

Geophysics ◽  
1977 ◽  
Vol 42 (4) ◽  
pp. 872-873
Author(s):  
Stephen Thyssen‐Bornemisza
Keyword(s):  
Research Work ◽  
Vertical Gradient ◽  
Gravity Gradient ◽  
Wind Gust ◽  
Near Surface ◽  
New Methods ◽  
Vertical Gravity Gradient ◽  
Surface Variation ◽  
Gradient Measurements ◽  
Vertical Gravity

In his paper, Fajklewicz discusses the improvement of vertical gravity gradient measurements arising from a very stable tower apparently not affected by wind gust vibration and climatic changes. Further, the lower plate where the gravity meter is resting can be changed in position to avoid possible disturbances from surface and near‐surface variation, and new methods for correcting and interpreting observed gradients over the vertical interval of about 3 m are presented. Some 1000 field stations were observed, including research work and industrial application.

POSSIBLE APPLICATION OF THE ANOMALOUS FREE‐AIR VERTICAL GRADIENT TO MARINE EXPLORATION

Geophysics ◽  
1966 ◽  
Vol 31 (1) ◽  
pp. 260-263
Author(s):  
Stephen Thyssen‐Bornemisza
Keyword(s):  
Vertical Cylinder ◽  
Vertical Gradient ◽  
Gravity Gradient ◽  
Average Gradient ◽  
Vertical Gravity Gradient ◽  
Free Air ◽  
Vertical Gravity ◽  
Lithologic Unit ◽  
Marine Exploration ◽  
Anomalous Average

Recently it could be shown (Thyssen‐Bornemisza, 1965) that a vertical lithologic unit cylinder generates a relatively strong anomalous free‐air vertical gravity gradient F′ along the cylinder axis. The following simple example may serve as a demonstration. A small vertical cylinder made of gold or tungsten, where radius r and length L are identical, would generate the anomalous average gradient F′∼3,223 Eötvös units over the interval h=r=L going from the cylinders top surface upward. Suppose r=l=1 cm, then an average gradient exceeding the earth’s normal free‐air vertical gradient F is present over the interval h=1 cm.

scholarly journals Migration of households from New York City and the Second Peak in Covid-19 cases in New Jersey, Connecticut and New York Counties.

2021 ◽  
Author(s):  
Adam T Schulman ◽  
Gyan Bhanot
Keyword(s):  
New York ◽  
New York City ◽  
New Jersey ◽  
York City ◽  
Infectious Agent ◽  
The United States ◽  
Control Measures ◽  
Simple Method ◽  
Address Data ◽  
Second Peak

The five boroughs of New York City (NYC) were early epicenters of the Covid-19 pandemic in the United States, with over 380,000 cases by May 31. High caseloads were also seen in nearby counties in New Jersey (NJ), Connecticut (CT) and New York (NY). The pandemic started in the area in March with an exponential rise in the number of daily cases, peaked in early April, briefly declined, and then, showed clear signs of a second peak in several counties. We will show that despite control measures such as lockdown and restriction of movement during the exponential rise in daily cases, there was a significant net migration of households from NYC boroughs to the neighboring counties in NJ, CT and NY State. We propose that the second peak in daily cases in these counties around NYC was due, in part, to the movement of people from NYC boroughs to these counties. We estimate the movement of people using "Change of Address" (CoA) data from the US Postal Service, provided under the "Freedom of Information Act" of 1967. To identify the timing of the second peak and the number of cases in it, we use a previously proposed SIR model, which accurately describes the early stages of the coronavirus pandemic in European countries. Subtracting the model fits from the data identified, we establish the timing and the number of cases, NCS, in the second peak. We then related the number of cases in the second peak to the county population density, P, and the excess Change of Address, ECoA, into each county using the simple model N_CS~P^α E_CoA^β which fits the data very well with α = 0.68, β = 0.31 (R^2 = 0.74, p = 1.3e-8). We also find that the time between the first and second peaks was proportional to the distance of the county seat from NY Penn Station, suggesting that this migration of households and disease was a directed flow and not a diffusion process. Our analysis provides a simple method to use change of address data to track the spread of an infectious agent, such as SARS-Cov-2, due to migrations away from epicenters during the initial stages of a pandemic.

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